Molecules that bind to PSCA polypeptides

Abstract

This document provides methods and materials involved in binding a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) to a PSCA polypeptide. For example, binders (e.g., antibodies, antigen binding fragments, antibody domains, CARs, cell engagers, and / or ADCs) that bind to a PSCA polypeptide and methods and materials for using one or more such binding molecules to treat a mammal (e.g., a human) having cancer are provided.

Description

[0001]Attorney Docket No.48881-0042WO1 / 05676 MOLECULES THAT BIND TO PSCA POLYPEPTIDES CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Patent Application Serial No. 63 / 465,126, filed on May 9, 2023. The disclosure of the prior application is considered part of, and is incorporated by reference in, the disclosure of this application. SEQUENCE LISTING This application contains a Sequence Listing that has been submitted electronically as an XML file named “48881-0042WO1_SL.xml.” The XML file, created on May 1, 2024, is 769,610 bytes in size. The material in the XML file is hereby incorporated by reference in its entirety. BACKGROUND 1. Technical Field This document relates to methods and materials involved in binding a molecule (e.g., an antibody, a fragment of an antibody, an antibody domain, a chimeric antigen receptor (CAR), a cell engager, or an antibody-drug conjugate (ADC)) to a PSCA polypeptide. For example, this document provides binders (e.g., antibodies, antigen binding fragments, antibody domains, CARs, cell engagers, or ADCs) that bind to a PSCA polypeptide and methods and materials for using such binders to treat cancer. This document also provides cells (e.g., host cells) designed to express one or more binders (e.g., antibodies, antigen binding fragments, antibody domains, CARs, or cell engagers) having the ability to bind to a PSCA polypeptide and methods and materials for using such cells to treat cancer. 2. Background Information Prostate stem cell antigen (PSCA) polypeptides are glycosylphosphatidylinositol (GPI)-anchored cell surface polypeptides belonging to the Thy-1 / Ly-6 family. As a GPI- anchored polypeptide, PSCA polypeptides are located in lipid rafts of the plasma Attorney Docket No.48881-0042WO1 / 05676 membrane and may have a role in regulating cell signaling events through receptor / ligand or other protein-protein binding, although the specific physiological function of PSCA polypeptides remain unclear. PSCA polypeptides are found to be upregulated in various types of solid tumors including prostate, bladder, renal cell, and pancreatic cancers; and its expression positively correlates with tumor grade and disease extent. PSCA polypeptides have been found to be expressed at 100% of bone metastases of prostate cancer (Saeki et al., Clin. Cancer Res., 16(14):3533-8 (2010)). These observations establish PSCA polypeptides as potential immunotherapeutic targets for prostate cancers. During last decades, several monoclonal antibodies were identified that target human PSCA polypeptides. Most of them were derived from mouse hybridomas, which were obtained by immunization of mice using PSCA polypeptide overexpressing cells lines followed by large-scale B cell screening. These antibodies eradicated PSCA polypeptide expressing xenografts in immunocompromised mice either through antibody- dependent cellular cytotoxicity (ADCC; clone 1G8, which inhibited growth of LAPC9 xenografts), antibody-drug conjugates (ADCs; clone 8D11 from Genentech), or chimeric antigen receptor armed T cells (CAR-T cells; Bellicum GoCAR-T BPX-601) (Foster et al., Mol. Ther., 25(9):2176-2188 (2017)). Among them, the Bellicum GoCAR-T BPX- 601 was evaluated in phase I / II clinical trials, and showed good tolerability (Stein et al., J. Clin. Oncol., 41(6):140-140 (2023)). SUMMARY This document provides methods and materials involved in binding a molecule (e.g., an antibody, an antigen binding fragment, an antibody domain, a CAR, a cell engager, or an ADC) to a PSCA polypeptide. For example, this document provides binders (e.g., antibodies, antigen binding fragments, antibody domains, CARs, cell engagers, or ADCs) that bind to a PSCA polypeptide and methods and materials for using one or more such binders to treat a mammal (e.g., a human) having cancer (e.g., prostate cancer such as metastatic prostate cancer, bladder cancer, renal cell cancer, and pancreatic cancer). Attorney Docket No.48881-0042WO1 / 05676 This document also provides cells (e.g., host cells) designed to express one or more binders (e.g., antibodies, antigen binding fragments, antibody domains, CARs, or cell engagers) having the ability to bind to a PSCA polypeptide and methods and materials for using such cells to treat cancer (e.g., prostate cancer such as metastatic prostate cancer, bladder cancer, renal cell cancer, and pancreatic cancer). As described herein, binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more CARs, one or more cell engagers, and / or one or more ADCs) can be designed to have the ability to bind to a PSCA polypeptide. For example, a binder (e.g., an antibody, an antigen binding fragment, an antibody domain, a CAR, a cell engager, or an ADC) provided herein can have the ability to bind to a polypeptide comprising, consisting essentially of, or consisting of the amino acid sequence of a human PSCA polypeptide as set forth in SEQ ID NO:129 (see, e.g., Example 6). As described herein, anti-PSCA binders (e.g., Clones #1, #2, #3, #4, #5, #6, #7, and #8) bind to PSCA polypeptides (e.g., human PSCA polypeptides). See, e.g., Figures 4 and 6. In addition, BiKEs designed to include the CDRs of Clone #5 exhibited ADCC of cells expressing PSCA polypeptides (Figures 9C and D). These results demonstrate that anti-PSCA binders provided herein can be used to treat cancer (e.g., prostate cancer such as metastatic prostate cancer, bladder cancer, renal cell cancer, and pancreatic cancer). In some cases, two sets of three CDRs of an antibody or antigen binding fragment provided herein (e.g., SEQ ID NOs:1-3 and 9-11; SEQ ID NOs:17-19 and SEQ ID NOs:25-27; SEQ ID NOs:33-35 and SEQ ID NOs:41-43; SEQ ID NOs:49-51 and SEQ ID NOs:57-59; SEQ ID NOs:65-67 and SEQ ID NOs:73-75; SEQ ID NOs:81-83 and SEQ ID NOs:89-91; SEQ ID NOs:97-99 and SEQ ID NOs:105-107; or SEQ ID NOs:113-115 and SEQ ID NOs:121-123) can be engineered into a CAR to create CAR+cells (e.g., CAR+T cells, CAR+stem cells such as CAR+induced pluripotent stem cells, or CAR+NK cells) having the ability to target PSCA+cells (e.g., PSCA+tumor cells and / or PSCA+tumor vasculature), can be engineered into an antibody structure that includes an Fc region to create antibodies having the ability to target PSCA+cells (e.g., Attorney Docket No.48881-0042WO1 / 05676 PSCA+tumor cells and / or PSCA+tumor vasculature) and induce ADCC against the target PSCA+cells, and / or can be engineered into a cell engager such as a bi-specific T cell engager (e.g., a BiTE), a bi-specific killer engager (e.g., a BiKE), and / or a tri-specific killer engager (e.g., a TriKE) to create cell engagers having the ability to target PSCA+cells (e.g., PSCA+tumor cells and / or PSCA+tumor vasculature) and induce one or more immune responses (e.g., T cell immune responses and / or ADCC using a cell engager in the absence of an Fc-containing antibody) against the target PSCA+cells. It is noted that BiKE- and TriKE-mediated killing can be referred to as ADCC even though it is not initiated by an Fc domain in cases when the engager lacks an Fc domain. In addition, as described herein, binders (e.g., one or more antibodies, one or more antigen binding fragments, and / or one or more antibody domains) provided herein can be used to create conjugates that include the binder and a drug. For example, ADCs such as full antibody-drug conjugates, Fab-drug conjugates, scFv-drug conjugates, and / or antibody domain-drug conjugates can be designed to include an appropriate binder provided herein to create the conjugate. Such conjugates can be used to deliver the drug payload to target cells such as cancer cells (e.g., PSCA+cancer cells) or cancer vasculature (e.g., PSCA+cancer vasculature). As also described herein, binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein can be used to treat a mammal (e.g., a human) having cancer. For example, a mammal (e.g., a human) having cancer (e.g., a PSCA+cancer) can be administered a composition comprising one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) described herein to reduce the number of cancer cells within the mammal, to induce ADCC against cancer cells within the mammal, and / or to increase the survival duration of the mammal from cancer (e.g., prostate cancer such as metastatic prostate cancer, bladder cancer, renal cell cancer, and pancreatic cancer). As also described herein, cells (e.g., host cells) can be designed to express one or more binders (e.g., antibodies, antigen binding fragments, antibody domains, CARs, or Attorney Docket No.48881-0042WO1 / 05676 cell engagers) having the ability to bind to a PSCA polypeptide. For example, cells such as T cells (e.g., CTLs), stem cells (e.g., induced pluripotent stem cells), or NK cells can be engineered to express one or more CARs having the ability to bind to a PSCA polypeptide. Such cells (e.g., PSCA-specific CAR+T cells or NK cells) can be used to treat cancer (e.g., prostate cancer such as metastatic prostate cancer, bladder cancer, renal cell cancer, and pancreatic cancer)). In some cases, a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein can be used to detect the presence or absence of a PSCA polypeptide. For example, a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein can be used to determine whether or not a sample (e.g., a biological sample such tumor biopsy) obtained from a mammal (e.g., a human) contains PSCA+cells (e.g., PSCA+cancer cells). Having the ability to detect the presence or absence of a PSCA polypeptide (e.g., PSCA+cancer cells) can allow clinicians, health professionals, and patients to make better decisions about possible treatment options. For example, detection of PSCA+cancer cells within a mammal can allow clinicians, health professionals, and patients to select an appropriate anti-cancer treatment that targets the PSCA+cancer cells. Such treatments that target the PSCA+cancer cells can include administration of one or more of the binders described herein having the ability to bind to a PSCA polypeptide and / or administration of one or more cells (e.g., PSCA-specific CAR+T cells or NK cells) designed to express a binder described herein. In general, one aspect of this document features an antibody comprising (or consisting essentially of, or consisting of): (i) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:1 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:2 (or SEQ ID NO:2 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:3 (or SEQ ID NO:3 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:9 (or SEQ ID NO:9 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:10 (or SEQ ID NO:10 with Attorney Docket No.48881-0042WO1 / 05676 one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:11 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions); (ii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:17 (or SEQ ID NO:17 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:18 (or SEQ ID NO:18 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:19 (or SEQ ID NO:19 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:25 (or SEQ ID NO:25 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:26 (or SEQ ID NO:26 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:27 (or SEQ ID NO:27 with one, two, or three amino acid additions, deletions, or substitutions); (iii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:33 (or SEQ ID NO:33 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:34 (or SEQ ID NO:34 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:35 (or SEQ ID NO:35 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:41 (or SEQ ID NO:41 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:42 (or SEQ ID NO:42 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:43 (or SEQ ID NO:43 with one, two, or three amino acid additions, deletions, or substitutions); (iv) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:49 (or SEQ ID NO:49 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:50 (or SEQ ID NO:50 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:51 (or SEQ ID NO:51 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:57 (or SEQ ID NO:57 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:58 (or SEQ ID NO:58 with one, two, or three amino acid additions, deletions, or Attorney Docket No.48881-0042WO1 / 05676 substitutions), and SEQ ID NO:59 (or SEQ ID NO:59 with one, two, or three amino acid additions, deletions, or substitutions); (v) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:65 (or SEQ ID NO:65 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:66 (or SEQ ID NO:66 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:67 (or SEQ ID NO:67 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:73 (or SEQ ID NO:73 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:74 (or SEQ ID NO:74 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:75 (or SEQ ID NO:75 with one, two, or three amino acid additions, deletions, or substitutions); (vi) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:81 (or SEQ ID NO:81 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:82 (or SEQ ID NO:82 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:83 (or SEQ ID NO:83 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:89 (or SEQ ID NO:89 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:90 (or SEQ ID NO:90 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:91 (or SEQ ID NO:91 with one, two, or three amino acid additions, deletions, or substitutions); (vii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:97 (or SEQ ID NO:97 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:98 (or SEQ ID NO:98 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:99 (or SEQ ID NO:99 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:105 (or SEQ ID NO:105 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:106 (or SEQ ID NO:106 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:107 (or SEQ ID NO:107 with one, two, or Attorney Docket No.48881-0042WO1 / 05676 three amino acid additions, deletions, or substitutions); or (viii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:113 (or SEQ ID NO:113 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:114 (or SEQ ID NO:114 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:115 (or SEQ ID NO:115 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:121 (or SEQ ID NO:121 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:122 (or SEQ ID NO:122 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:123 (or SEQ ID NO:123 with one, two, or three amino acid additions, deletions, or substitutions). The antibody can comprise the ability to bind to SEQ ID NO:129. The antibody can comprise the heavy chain variable domain or region of the (i) and the light chain variable domain or region of the (i). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:8, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:16. The antibody can comprise the heavy chain variable domain or region of the (ii) and the light chain variable domain or region of the (ii). The heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:24, and the light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:32. The antibody can comprise the heavy chain variable domain or region of the (iii) and the light chain variable domain or region of the (iii). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:40, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:48. The antibody can comprise the heavy chain variable domain or region of the (iv) and the light chain variable domain or region of the (iv). The heavy chain variable domain or Attorney Docket No.48881-0042WO1 / 05676 region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:56, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:64. The antibody can comprise the heavy chain variable domain or region of the (v) and the light chain variable domain or region of the (v). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:72, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:80. The antibody can comprise the heavy chain variable domain or region of the (vi) and the light chain variable domain or region of the (vi). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:88 and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:96. The antibody can comprise the heavy chain variable domain or region of the (vii) and the light chain variable domain or region of the (vii). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:104, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:112. The antibody can comprise the heavy chain variable domain or region of the (viii) and the light chain variable domain or region of the (viii). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:120, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:128. The antibody can be a monoclonal antibody. The antibody can be an scFv antibody. This paragraph can be referred to as first aspect paragraph. In another aspect, this document features an antigen binding fragment comprising (or consisting essentially of, or consisting of): (i) a heavy chain variable domain or region Attorney Docket No.48881-0042WO1 / 05676 comprising the amino acid sequences set forth in SEQ ID NO:1 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:2 (or SEQ ID NO:2 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:3 (or SEQ ID NO:3 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:9 (or SEQ ID NO:9 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:10 (or SEQ ID NO:10 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:11 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions); (ii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:17 (or SEQ ID NO:17 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:18 (or SEQ ID NO:18 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:19 (or SEQ ID NO:19 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:25 (or SEQ ID NO:25 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:26 (or SEQ ID NO:26 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:27 (or SEQ ID NO:27 with one, two, or three amino acid additions, deletions, or substitutions); (iii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:33 (or SEQ ID NO:33 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:34 (or SEQ ID NO:34 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:35 (or SEQ ID NO:35 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:41 (or SEQ ID NO:41 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:42 (or SEQ ID NO:42 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:43 (or SEQ ID NO:43 with one, two, or three amino acid additions, deletions, or substitutions); (iv) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:49 (or Attorney Docket No.48881-0042WO1 / 05676 SEQ ID NO:49 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:50 (or SEQ ID NO:50 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:51 (or SEQ ID NO:51 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:57 (or SEQ ID NO:57 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:58 (or SEQ ID NO:58 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:59 (or SEQ ID NO:59 with one, two, or three amino acid additions, deletions, or substitutions); (v) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:65 (or SEQ ID NO:65 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:66 (or SEQ ID NO:66 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:67 (or SEQ ID NO:67 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:73 (or SEQ ID NO:73 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:74 (or SEQ ID NO:74 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:75 (or SEQ ID NO:75 with one, two, or three amino acid additions, deletions, or substitutions); (vi) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:81 (or SEQ ID NO:81 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:82 (or SEQ ID NO:82 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:83 (or SEQ ID NO:83 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:89 (or SEQ ID NO:89 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:90 (or SEQ ID NO:90 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:91 (or SEQ ID NO:91 with one, two, or three amino acid additions, deletions, or substitutions); (vii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:97 (or SEQ ID NO:97 with one, two, or three amino acid additions, deletions, or Attorney Docket No.48881-0042WO1 / 05676 substitutions), SEQ ID NO:98 (or SEQ ID NO:98 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:99 (or SEQ ID NO:99 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:105 (or SEQ ID NO:105 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:106 (or SEQ ID NO:106 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:107 (or SEQ ID NO:107 with one, two, or three amino acid additions, deletions, or substitutions); or (viii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:113 (or SEQ ID NO:113 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:114 (or SEQ ID NO:114 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:115 (or SEQ ID NO:115 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:121 (or SEQ ID NO:121 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:122 (or SEQ ID NO:122 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:123 (or SEQ ID NO:123 with one, two, or three amino acid additions, deletions, or substitutions). The antigen binding fragment can comprise the ability to bind to SEQ ID NO:129. The antigen binding fragment can comprise the heavy chain variable domain or region of the (i) and the light chain variable domain or region of the (i). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:8, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:16. The antigen binding fragment can comprise the heavy chain variable domain or region of the (ii) and the light chain variable domain or region of the (ii). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:24, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:32. The antigen Attorney Docket No.48881-0042WO1 / 05676 binding fragment can comprise the heavy chain variable domain or region of the (iii) and the light chain variable domain or region of the (iii). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:40, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:48. The antigen binding fragment can comprise the heavy chain variable domain or region of the (iv) and the light chain variable domain or region of the (iv). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:56, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:64. The antigen binding fragment can comprise the heavy chain variable domain or region of the (v) and the light chain variable domain or region of the (v). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:72, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:80. The antigen binding fragment can comprise the heavy chain variable domain or region of the (vi) and the light chain variable domain or region of the (vi). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:88, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:96. The antigen binding fragment can comprise the heavy chain variable domain or region of the (vii) and the light chain variable domain or region of the (vii). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:104, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:112. The antigen binding fragment can comprise the heavy chain variable domain or region of the (viii) and the light chain Attorney Docket No.48881-0042WO1 / 05676 variable domain or region of the (viii). The heavy chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:120, and the light chain variable domain or region can comprise an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:128. The antigen binding fragment can be monoclonal. The antigen binding fragment can be a Fab. This paragraph can be referred to as second aspect paragraph. In another aspect, this document features an antibody domain comprising (or consisting essentially of, or consisting of): (i) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:1 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:2 (or SEQ ID NO:2 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:3 (or SEQ ID NO:3 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:9 (or SEQ ID NO:9 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:10 (or SEQ ID NO:10 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:11 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions); (ii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:17 (or SEQ ID NO:17 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:18 (or SEQ ID NO:18 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:19 (or SEQ ID NO:19 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:25 (or SEQ ID NO:25 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:26 (or SEQ ID NO:26 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:27 (or SEQ ID NO:27 with one, two, or three amino acid additions, deletions, or substitutions); (iii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:33 (or SEQ ID NO:33 with one, two, or three amino acid additions, deletions, or Attorney Docket No.48881-0042WO1 / 05676 substitutions), SEQ ID NO:34 (or SEQ ID NO:34 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:35 (or SEQ ID NO:35 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:41 (or SEQ ID NO:41 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:42 (or SEQ ID NO:42 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:43 (or SEQ ID NO:43 with one, two, or three amino acid additions, deletions, or substitutions); (iv) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:49 (or SEQ ID NO:49 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:50 (or SEQ ID NO:50 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:51 (or SEQ ID NO:51 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:57 (or SEQ ID NO:57 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:58 (or SEQ ID NO:58 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:59 (or SEQ ID NO:59 with one, two, or three amino acid additions, deletions, or substitutions); (v) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:65 (or SEQ ID NO:65 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:66 (or SEQ ID NO:66 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:67 (or SEQ ID NO:67 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:73 (or SEQ ID NO:73 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:74 (or SEQ ID NO:74 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:75 (or SEQ ID NO:75 with one, two, or three amino acid additions, deletions, or substitutions); (vi) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:81 (or SEQ ID NO:81 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:82 (or SEQ ID NO:82 with one, Attorney Docket No.48881-0042WO1 / 05676 two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:83 (or SEQ ID NO:83 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:89 (or SEQ ID NO:89 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:90 (or SEQ ID NO:90 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:91 (or SEQ ID NO:91 with one, two, or three amino acid additions, deletions, or substitutions); (vii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:97 (or SEQ ID NO:97 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:98 (or SEQ ID NO:98 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:99 (or SEQ ID NO:99 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:105 (or SEQ ID NO:105 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:106 (or SEQ ID NO:106 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:107 (or SEQ ID NO:107 with one, two, or three amino acid additions, deletions, or substitutions); or (viii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:113 (or SEQ ID NO:113 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:114 (or SEQ ID NO:114 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:115 (or SEQ ID NO:115 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:121 (or SEQ ID NO:121 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:122 (or SEQ ID NO:122 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:123 (or SEQ ID NO:123 with one, two, or three amino acid additions, deletions, or substitutions). The antibody domain can comprise the ability to bind to SEQ ID NO:129. The antibody domain can comprise the heavy chain variable domain or region of (i). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:8. Attorney Docket No.48881-0042WO1 / 05676 The antibody domain can comprise the light chain variable domain or region of (i). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:16. The antibody domain can comprise the heavy chain variable domain or region of (ii). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:24. The antibody domain can comprise the light chain variable domain or region of (ii). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:32. The antibody domain can comprise the heavy chain variable domain or region of (iii). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:40. The antibody domain can comprise the light chain variable domain or region of (iii). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:48. The antibody domain can comprise the heavy chain variable domain or region of (iv). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:56. The antibody domain can comprise light chain variable domain or region of (iv). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:64. The antibody domain can comprise the heavy chain variable domain or region of (v). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:72. The antibody domain can comprise the light chain variable domain or region of (v). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:80. The antibody domain can comprise the heavy chain variable domain or region of (vi). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:88. The antibody domain can comprise light chain variable domain or region of (vi). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ Attorney Docket No.48881-0042WO1 / 05676 ID NO:96. The antibody domain can comprise the heavy chain variable domain or region of (vii). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:104. The antibody domain can comprise the light chain variable domain or region of (vii). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:112. The antibody domain can comprise the heavy chain variable domain or region of (viii). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:120. The antibody domain can comprise light chain variable domain or region of (viii). The antibody domain can comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:128. The antibody domain can be monoclonal. The antibody domain can be a VH domain. The antibody domain can be a VL domain. This paragraph can be referred to as third aspect paragraph. In another aspect, this document features a chimeric antigen receptor comprising (or consisting essentially of, or consisting of) an antigen binding domain, a hinge, a transmembrane domain, and one or more signaling domains, wherein the antigen binding domain comprises (or consists essentially of, or consists of) any antibody, any antigen- binding fragment, or any antibody domain of any of first aspect paragraph, second aspect paragraph, or third aspect paragraph. The antigen binding domain can comprise a scFv having the ability to bind to a PSCA polypeptide. The antigen binding domain can comprise a VH domain having the ability to bind to a PSCA polypeptide. The hinge can comprise a hinge set forth in Example 15. The transmembrane domain can comprise a transmembrane domain set forth in Example 16. The chimeric antigen receptor can comprise one or more signaling domains set forth in Example 17. This paragraph can be referred to as fourth aspect paragraph. In another aspect, this document features a cell comprising (or consisting essentially of, or consisting of) any chimeric antigen receptor of the preceding paragraph. The cell can be a T cell, a stem cell, or an NK cell. Attorney Docket No.48881-0042WO1 / 05676 In another aspect, this document features a cell engager comprising (or consisting essentially of, or consisting of) a first antigen binding domain, a linker, and a second antigen binding domain, wherein the first antigen binding domain comprises (or consists essentially of, or consists of) any antibody, any antigen-binding fragment, or any antibody domain of any of first aspect paragraph, second aspect paragraph, or third aspect paragraph. The first antigen binding domain can comprise a VH domain having the ability to bind to a PSCA polypeptide. The first antigen binding domain can comprise a VL domain having the ability to bind to a PSCA polypeptide. The first antigen binding domain can comprise an Fab having the ability to bind to a PSCA polypeptide. The first antigen binding domain can be an IgG having the ability to bind to a PSCA polypeptide. The linker can comprise a linker set forth in Example 12 or Example 15. The second antigen binding domain can bind to a polypeptide expressed on the surface of T cells. The polypeptide expressed on the surface of T cells can be a CD3 polypeptide. The second antigen binding domain can be an antigen binding domain set forth in Example 19. The second antigen binding domain can bind to a polypeptide expressed on the surface of NK cells. The polypeptide expressed on the surface of NK cells can be a CD16a, NKG2A, NKG2D, NKp30, NKp44, or NKp46 polypeptide. The second antigen binding domain can be an antigen binding domain set forth in Example 20. The cell engager can comprise a third antigen binding domain. The third antigen binding domain can bind to a polypeptide expressed on the surface of NK cells. The polypeptide expressed on the surface of NK cells can be a CD16a, NKG2A, NKG2D, NKp30, NKp44, or NKp46 polypeptide. The third antigen binding domain can be an antigen binding domain set forth in Example 20. This paragraph can be referred to as fifth aspect paragraph. In another aspect, this document features a nucleic acid comprising (or consisting essentially of, or consisting of) a nucleic acid sequence encoding at least part of the antibody, the antigen-binding fragment, or the antibody domain of any of first aspect paragraph, second aspect paragraph, or third aspect paragraph. The nucleic acid sequence can encode the heavy chain variable domain or region of any one of the (i)- (viii) of first aspect paragraph. The nucleic acid sequence can encode the light chain Attorney Docket No.48881-0042WO1 / 05676 variable domain or region of any one of the (i)-(viii) of first aspect paragraph. The nucleic acid can be a viral vector. The nucleic acid can be a phagemid. In another aspect, this document features a nucleic acid comprising (or consisting essentially of, or consisting of) a nucleic acid sequence encoding any chimeric antigen receptor of fourth aspect paragraph or any cell engager of fifth aspect paragraph. The nucleic acid can be a viral vector. The nucleic acid can be a phagemid. In another aspect, this document features a host cell comprising (or consisting essentially of, or consisting of) any nucleic acid of the preceding paragraph. This paragraph can be referred to as sixth aspect paragraph. In another aspect, this document features a host cell that expresses any chimeric antigen receptor of fourth aspect paragraph or any cell engager of fifth aspect paragraph. The host cell can be a T cell, stem cell, or NK cell. This paragraph can be referred to as seventh aspect paragraph. In another aspect, this document features an antibody-drug conjugate (ADC) comprising (or consisting essentially of, or consisting of) an antigen binging domain covalently linked to a drug, wherein the antigen binging domain comprises an antibody, an antigen binding fragment, or an antibody domain of any of first aspect paragraph, second aspect paragraph, or third aspect paragraph. The antigen binding domain can comprise a scFv having the ability to bind to a PSCA polypeptide. The antigen binding domain can comprise a Fab having the ability to bind to a PSCA polypeptide. The antigen binding domain can comprise a VH domain having the ability to bind to a PSCA polypeptide. The antigen binding domain can comprise a VL domain having the ability to bind to a PSCA polypeptide. The antigen binding domain can comprise an IgG having the ability to bind to a PSCA polypeptide. The drug can be selected from the group consisting of auristatins, mertansine, or pyrrolobenzodiazepine (PBD) dimers. This paragraph can be referred to as eighth aspect paragraph. In another aspect, this document features a composition comprising (or consisting essentially of, or consisting of) an antibody, an antigen binding fragment, or an antibody domain of any of first aspect paragraph, second aspect paragraph, or third aspect paragraph. The composition can comprise any antibody of first aspect paragraph. The Attorney Docket No.48881-0042WO1 / 05676 composition can comprise any antigen binding fragment of second aspect paragraph. The composition can comprise any antibody domain of third aspect paragraph. In another aspect, this document features a composition comprising (or consisting essentially of, or consisting of) any cell engager of fifth aspect paragraph. In another aspect, this document features a composition comprising (or consisting essentially of, or consisting of) any cell of sixth aspect paragraph or seventh aspect paragraph. In another aspect, this document features a composition comprising (or consisting essentially of, or consisting of) any ADC of any one of eighth aspect paragraph. The composition can comprise a checkpoint inhibitor. The checkpoint inhibitor can be selected from the group consisting of cemiplimab, nivolumab, pembrolizumab, JTX- 4014, spartalizumab, camrelizumab, sintilimab, tislelizumab, toripalimab, dostarlimab, INCMGA00012, AMP-224, AMP-514, avelumab, durvalumab, atezolizumab, KN035, CK-301, AUNP12, CA-170, BMS-986189, and ipilimumab. In another aspect, this document features a method of treating a mammal having cancer. The method comprises (or consists essentially of, or consists of) administering, to the mammal, a composition of any of the preceding four paragraphs. The mammal can be a human. The cancer can be a PSCA+cancer. The PSCA+cancer can be selected from the group consisting of PSCA+prostate cancer, PSCA+metastatic prostate cancer, PSCA+bladder cancer, PSCA+renal cell cancer, and PSCA+pancreatic cancer. The number of cancer cells within the mammal can be reduced following the administering step. In another aspect, this document features a method of treating a mammal having cancer. The method comprises (or consists essentially of, or consists of) (a) administering, to the mammal, a composition of any of the preceding four paragraphs referred to in the preceding paragraph, and (b) administering, to the mammal, a composition comprising a checkpoint inhibitor. The mammal can be a human. The cancer can be a PSCA+cancer. The PSCA+cancer can be selected from the group consisting of PSCA+prostate cancer, PSCA+metastatic prostate cancer, PSCA+bladder cancer, PSCA+renal cell cancer, and PSCA+pancreatic cancer. The checkpoint inhibitor Attorney Docket No.48881-0042WO1 / 05676 can be selected from the group consisting of cemiplimab, nivolumab, pembrolizumab, JTX-4014, spartalizumab, camrelizumab, sintilimab, tislelizumab, toripalimab, dostarlimab, INCMGA00012, AMP-224, AMP-514, avelumab, durvalumab, atezolizumab, KN035, CK-301, AUNP12, CA-170, BMS-986189, and ipilimumab. The number of cancer cells within the mammal can be reduced following the administering steps (a) and (b). In another aspect, this document features a method for binding a binding molecule to a PSCA polypeptide. The method comprises (or consists essentially of, or consists of) contacting the PSCA polypeptide with an antibody, an antigen binding fragment, or an antibody domain of any of first aspect paragraph, second aspect paragraph, or third aspect paragraph. The contacting can be performed in vitro. The contacting can be performed in vivo. The contacting can be performed within a mammal by administering the antibody, the antigen binding fragment, or the antibody domain to the mammal. The mammal can be a human. In another aspect, this document features a method for binding a binding molecule to a PSCA polypeptide. The method comprises (or consists essentially of, or consists of) contacting the PSCA polypeptide with any chimeric antigen receptor of fourth aspect paragraph, any cell engager of fifth aspect paragraph, or any ADC of eighth aspect paragraph. The contacting can be performed in vitro. The contacting can be performed in vivo. The contacting can be performed within a mammal by administering the chimeric antigen receptor, the cell engager, or the ADC to the mammal. The mammal can be a human. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Methods and materials are described herein for use in the present disclosure; other, suitable methods and materials known in the art can also be used. The materials, methods, and examples are illustrative only and not intended to be limiting. All publications, patent applications, patents, sequences, database entries, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. Attorney Docket No.48881-0042WO1 / 05676 The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. DESCRIPTION OF DRAWINGS Figure 1 is a schematic of an exemplary CAR construct designed to express a CAR. A promotor sequence (e.g., a CMV immediate early promotor sequence) can be followed by a signal peptide sequence (e.g., a GM-CSF signal peptide sequence), followed by a scFv provided herein, followed by an optional linker (not shown), followed by an optional hinge (e.g., a CD8 hinge sequence; not shown), followed by a transmembrane sequence (e.g., a CD8 transmembrane sequence), followed by one or more intracellular signaling domain sequences (e.g., a 4-1BB (CD137) intracellular signaling domain sequence and a CD3? intracellular signaling domain sequence). Figure 2 is a schematic of an exemplary CAR construct designed to express a CAR. A promotor sequence (e.g., a CMV immediate early promotor sequence) can be followed by a signal peptide sequence (e.g., a GM-CSF signal peptide sequence), followed by a VH domain (or VL domain) provided herein (e.g., a VH domain designed to include one set of three CDRs of a heavy chain provided herein such as SEQ ID NOs:1-3; SEQ ID NOs:17-19 SEQ ID NOs:33-35; SEQ ID NOs:49-51; SEQ ID NOs:65- 67; SEQ ID NOs:81-83; SEQ ID NOs:97-99; or SEQ ID NOs:113-115; or a VL domain designed to include one set of three CDRs of a light chain provided herein such as SEQ ID NOs:9-11; SEQ ID NOs:25-27; SEQ ID NOs:41-43; SEQ ID NOs:57-59; SEQ ID NOs:73-75; SEQ ID NOs:89-91; SEQ ID NOs:105-107; or SEQ ID NOs:121-123), followed by an optional linker (not shown), followed by an optional hinge (e.g., a CD8 hinge sequence; not shown), followed by a transmembrane sequence (e.g., a CD8 transmembrane sequence), followed by one or more intracellular signaling domain sequences (e.g., a 4-1BB (CD137) intracellular signaling domain sequence and a CD3? intracellular signaling domain sequence). Attorney Docket No.48881-0042WO1 / 05676 Figure 3 is a schematic of an exemplary BiTE designed using CDR1, CDR2, and CDR3 of a heavy chain and CDR1, CDR2, and CDR3 of a light chain in an Ig format (e.g., an IgG1 format). A humanized anti-CD3 scFv (e.g., an gOKT3-7 scFv set forth in U.S. Patent No.6,750,325) can be linked to the C-terminus of the light chain via a linker (e.g., a (G4S)3 linker (SEQ ID NO: 135)). Figure 4 is a graph plotting affinity enhanced clones binding to recombinant human PSCA polypeptides with comparisons to the original clone G7, as tested by ELISA. Figures 5A-5D. Characterization of the affinity enhanced Clone #5 (F12). Figures 5A and 5B provide a comparison of binding kinetics of G7 (Figure 5A) and F12 (Figure 5B) by BlitZ, which is a bio-interferometry method that measures antibody on- rates and off-rates. The enhanced binding affinity of Clone #5 is mainly ascribed to the decreased Koff rate. Figures 5C and 5D show results evaluating binding of G7 and F12 to cell surface PSCA polypeptides on PC3 cells. F12 exhibited substantial binding to PC3-PSCA+cells without binding to PC3-PSCA- cells. Figures 6A-6D. Testing internalization of IgG1 F12 on prostate cancer cell lines using a pH sensitive dye, which was conjugated to the F12 antibody and only illuminates under the low pH environment. Figure 6A is a graph showing F12 internalized into acid lysosome in a concentration and time dependent manner. The internalization was dependent on PSCA polypeptide expression on the cell surface of PC3 cells. Figure 6B is a graph showing F12 internalized into acid lysosome in a concentration and time dependent manner. The internalization was dependent on PSCA polypeptide expression on the cell surface of Du145 cells. Figure 6C is a graph showing that F12 internalization is dependent on temperature. 4°C did not promote F12 internalization. Figure 6D is a graph showing that F12 (dye) conjugate internalization can be specifically inhibited by the naked IgG1 antibody in a concentration dependent manner both on PC3 and Du145 cells. Figures 7A-7E. Generation of F12-MMAE ADC and testing on mouse xenograft model. Figure 7A. The scheme of F12-MMAE ADC that is designed to include an antibody (e.g., F12), and lysine mediated conjugation with the dipeptidyl linker, PAB Attorney Docket No.48881-0042WO1 / 05676 spacer and MMAE payload. Figure 7B. Mass spectrum to determine the drug-antibody- ratio (DAR) of 2. Figure 7C. The in vitro cell killing of F12-MMAE-ADC testing on PC3-PSCA cell lines. The payload MMAE killing efficacy was comparable to the PBD payload. Figure 7D. The anti-tumor efficacy on PC3-PSCA xenograft NSG mouse model. PC3-PSCA cells (5 million) were implanted into mice flank with mitragel (50%). Two weeks later, both naked IgG1 F12 and F12-ADC were injected into mice through i.p. injection at once weekly with totally four doses. Tumor size and mice body weights were monitored every three days. Results showed that the ADC reduced tumor volumes, while IgG1 F12 alone did not. Figure 7E. The ADC was safe as no body weight loss was observed. Figures 8A-8D. Generation of BiKEs containing F12 targeting PSCA polypeptides and an anti-human CD16A antibody domain (VH7, shown as cross hatched; Figure 8A). IgG1 F12 is a typical IgG1 antibody with wild type Fc for implementing ADCC. In 1+2 BiKE, the monovalent VH7 was fused to IgG1 heavy chain N terminal region through a flexible linker. The knob-into-hole technique was used for creating an asymmetric molecule. The LALAPG mutations were introduced into the Fc to silent the Fc mediated effector function. Thus, the ADCC was only triggered by VH7. In 2+2 BiKE, bivalent VH7 domains were introduced to increase CD16A engagement. The Fc in 2+2 BiKE also contained the LALAPG mutation. Figure 8B. SDS-PAGE for IgG and BiKEs. IgG1 and 2+2 BiKE were produced by co-transfect equal molar ration of HC and LC plasmids, while the 1+2 BiKE was expressed by co-transfected the hole HC, knob HC, and the LC in 1:1:2 ratio. Figure 8C is a schematic showing how the IgG1 F12 mounts ADCC though the WT Fc. Figure 8D is a schematic showing how the BiKE evokes ADCC though formation of immune synapse by simultaneously binding tumor antigen on tumor cells and binding to CD16A on NK cells. Figures 9A-9D. Characterization of BiKEs in terms of antigen binding and in vitro ADCC using the Promega ADCC assay kits, Jurkat T cells stably expressing CD16A, and NFAT-RE driven luciferase expression cassette. Figure 9A shows binding of IgG1 F12 and BiKEs to the recombinant PSCA polypeptides. BiKEs exhibited lower binding affinity to PSCA polypeptides than IgG1 F12. Figure 9B shows binding of IgG1 Attorney Docket No.48881-0042WO1 / 05676 F12 and BiKEs to recombinant human CD16A. The lower signal for IgG1 was consistent to the binding of Fc to CD16A, which the anti-CD16A antibody based BiKE showed much higher affinity to CD16A. Figure 9C shows ADCC of IgG1 F12 and BiKEs using the promega ADCC kit. The potency of 2+2 BiKE was similar as IgG1 F12. IgG1 F12 exhibited the highest efficacy. The higher binding affinity to PSCA polypeptides for IgG1 F12 compared to BiKEs may explain the higher efficacy of IgG1 F12. 2+2 BiKE was more potent than 1+2 BiKE, demonstrating the ability of bivalent VH7. The ADCC effect was specific since no ADCC signals were observed in PSCA negative PC3 cells (Figure 9D), and in groups that did not contain the target cells (Effector cells + Abs). DETAILED DESCRIPTION This document provides binders (e.g., antibodies, antigen binding fragments, antibody domains, CARs, cell engagers, and ADCs) that bind (e.g., specifically bind) to a PSCA polypeptide (e.g., a human PSCA polypeptide). For example, the document provides binders (e.g., antibodies, antigen binding fragments, antibody domains, CARs, cell engagers, and ADCs) that bind (e.g., specifically bind) to a polypeptide comprising, consisting essentially of, or consisting of the amino acid set forth in SEQ ID NO:129 and / or an extracellular domain thereof (see, e.g., Example 6). The term “antibody” as used herein includes polyclonal antibodies, monoclonal antibodies, recombinant antibodies, humanized antibodies, human antibodies, chimeric antibodies, multi-specific antibodies (e.g., bispecific antibodies) formed from at least two antibodies, diabodies, single-chain variable fragment antibodies (e.g., scFv antibodies), and tandem single-chain variable fragments antibody (e.g., taFv). A diabody can include two chains, each having a heavy chain variable domain and a light chain variable domain, either from the same or from different antibodies (see, e.g., Hornig and Färber-Schwarz, Methods Mol. Biol., 907:713-27 (2012); and Brinkmann and Kontermann, MAbs., 9(2):182-212 (2017)). The two variable regions can be connected by a polypeptide linker (e.g., a polypeptide linker having five to ten residues in length or a polypeptide linker as set forth in Example 12). In some cases, an interdomain disulfide bond can be present in Attorney Docket No.48881-0042WO1 / 05676 one or both of the heavy chain variable domain and light chain variable domain pairs of the diabody. A scFv is a single-chain polypeptide antibody in which the heavy chain variable domain and the light chain variable domain are directly connected or connected via a polypeptide linker (e.g., a polypeptide linker having eight to 18 residues in length or a polypeptide linker as set forth in Example 12). See, also, Chen et al., Adv. Drug Deliv. Rev., 65(10):1357-1369 (2013). A scFv can be designed to have an orientation with the heavy chain variable domain being followed by the light chain variable domain or can be designed to have an orientation with the light chain variable domain being followed by the heavy chain variable domain. In both cases, the optional linker can be located between the two domains. Examples of scFv structures of scFv’s provided herein include, without limitation, those structures set forth in Figures 7-9, 12, 13A-13B, 14A- 14B, 15A-15B, 16A-16B, 17A-17B, 18A-18B, 19A-19B, 20A-20B, and 21A-21B. An antibody provided herein can include the CDRs as described herein (e.g., as described in Table 49) and can be configured to be a human antibody, a humanized antibody, or a chimeric antibody. In some cases, an antibody provided herein can include the CDRs as described herein (e.g., as described in Table 49) and can be a monoclonal antibody. In some cases, an antibody provided herein can include the CDRs as described herein (e.g., as described in Table 49) and can be configured as a scFv antibody. The term “antigen binding fragment” as used herein refers to a fragment of an antibody (e.g., a fragment of a humanized antibody, a fragment of a human antibody, or a fragment of a chimeric antibody) having the ability to bind to an antigen. Examples of antigen binding fragments include, without limitation, Fab, Fab’, or F(ab’)2antigen binding fragments. An antigen binding fragment provided herein can include the CDRs as described herein (e.g., as described in Table 49) and can be configured to be a human antigen binding fragment, a humanized antigen binding fragment, or a chimeric antigen binding fragment. In some cases, an antigen binding fragment provided herein can include the CDRs as described herein (e.g., as described in Table 49) and can be a monoclonal antigen binding fragment. In some cases, an antigen binding fragment provided herein can include the CDRs as described herein (e.g., as described in Table 49) and can be configured as a Fab antibody. In some cases, a Fab antibody can include a Attorney Docket No.48881-0042WO1 / 05676 partial hinge sequence (e.g., EPKSCDKT (SEQ ID NO:248)) for disulfide bonding between heavy and light chains of the Fab. Examples of Fab’s provided herein include, without limitation, those structures set forth in Figures 2-6. The term “antibody domain” as used herein refers to a domain of an antibody such as a heavy chain variable domain (VH domain) or a light chain variable domain (VL domain) in the absence of one or more other domains of an antibody. In some cases, an antibody domain can be a single antibody domain (e.g., a VH domain or a VL domain) having the ability to bind to an antigen. An antibody domain provided herein can include the CDRs as described herein (e.g., as described in Table 49) and can be a human antibody domain (e.g., a human VH domain), a humanized antibody domain (e.g., a humanized VH domain), or a chimeric antibody domain (e.g., a chimeric VH domain). In some cases, an antibody domain provided herein can include the CDRs as described herein (e.g., as described in Table 49) and can be a monoclonal antibody domain. In some cases, an antibody domain provided herein can include the CDRs as described herein (e.g., as described in Table 49) and can be engineered as a single VH domain or a single VL domain. Examples of VH domain’s provided herein include, without limitation, those heavy chain variable domains set forth in Figures 2A, 3A, 4A, 5A, 6A, 7A, 8A, and 9A. Examples of VL domain’s provided herein include, without limitation, those light chain variable domains set forth in Figures 2B, 3B, 4B, 5B, 6B, 7B, 8B, and 9B. An anti-PSCA antibody, anti-PSCA antigen binding fragment, or anti-PSCA antibody domain provided herein can be of the IgA-, IgD-, IgE-, IgG-, or IgM-type, including IgG- or IgM-types such as, without limitation, IgG1-, IgG2-, IgG3-, IgG4-, IgM1-, and IgM2-types. In some cases, an antibody provided herein (e.g., an anti-PSCA antibody) can be a scFv antibody. In some cases, an antigen binding fragment provided herein (e.g., an anti-PSCA antibody fragment) can be a Fab. In some cases, an antibody provided herein (e.g., an anti-PSCA antibody) can be a fully intact antibody having the structure set forth in Example 9. In some cases, an antibody domain provided herein (e.g., an anti-PSCA antibody domain) can be a VH domain or a VL domain. Attorney Docket No.48881-0042WO1 / 05676 In some cases, an anti-PSCA antibody, anti-PSCA antigen binding fragment, or anti-PSCA antibody domain provided herein can be fully human. In some cases, an anti- PSCA antibody, anti-PSCA antigen binding fragment, or anti-PSCA antibody domain provided herein can have a low risk for inducing immunogenicity within a human. The term “chimeric antigen receptor” as used herein refers to a chimeric polypeptide that is designed to include an optional signal peptide, an antigen binding domain, an optional hinge, a transmembrane domain, and one or more intracellular signaling domains. As described herein, the antigen binding domain of a CAR provided herein can be designed to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). For example, a CAR provided herein can be designed to include the components of an antibody, antigen binding fragment, and / or antibody domain described herein (e.g., a combination of CDRs) as an antigen binding domain provided that that antigen binding domain has the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). In some examples, a CAR provided herein can be designed to include an antigen binding domain that includes a single set of three CDRs (e.g., a CDR1, CDR2, and CDR3) of an antibody domain (e.g., a VH domain) provided herein (e.g., a VH domain designed to include one set of three CDRs of a heavy chain provided herein such as SEQ ID NOs:1-3; SEQ ID NOs:17-19 SEQ ID NOs:33-35; SEQ ID NOs:49-51; SEQ ID NOs:65-67; SEQ ID NOs:81-83; SEQ ID NOs:97-99; or SEQ ID NOs:113-115). In some examples, a CAR provided herein can be designed to include an antigen binding domain that includes a single set of three CDRs (e.g., a CDR1, CDR2, and CDR3) of an antibody domain (e.g., a VL domain) provided herein (e.g., a VL domain designed to include one set of three CDRs of a light chain provided herein such as SEQ ID NOs:9-11; SEQ ID NOs:25-27; SEQ ID NOs:41-43; SEQ ID NOs:57-59; SEQ ID NOs:73-75; SEQ ID NOs:89-91; SEQ ID NOs:105-107; or SEQ ID NOs:121-123). In some cases, an antigen binding domain of a CAR targeting a PSCA polypeptide can be designed to include a scFv antibody described herein such as a scFv set forth in Examples 7, 10, or 11. Examples of CAR structures that can be used to make a CAR provided herein include, without limitation, those set forth in Figures 29-44. Attorney Docket No.48881-0042WO1 / 05676 In some cases, a CAR provided herein can be designed to include a signal peptide. Any appropriate signal peptide can be used to design a CAR described herein. Examples of signal peptide that can be used to make a CAR described herein include without limitation, a human IGKV1-39-derived signal peptide, IGKV1-16, IGKV1-33, IGKV3- 11, IGKV4-1, or IGKV6-21. In some cases, a CAR provided herein can be designed to include a signal peptide that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 14. In some cases, a CAR provided herein can be designed to include a signal peptide that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 14 with one, two, three, four, five, six, seven, eight, nine, or ten amino acid deletions, additions, substitutions, or combinations thereof. In some cases, a CAR provided herein can be designed to include a signal peptide that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 14 with two or less, three or less, four or less, five or less, six or less, seven or less, eight or less, nine or less, or ten or less amino acid deletions, additions, substitutions, or combinations thereof. In some cases, a CAR provided herein can be designed to include a hinge. Any appropriate hinge can be used to design a CAR described herein. Examples of hinges that can be used to make a CAR described herein include, without limitation, Ig-derived hinges (e.g., an IgG1-derived hinge, an IgG2-derived hinge, or an IgG4-derived hinge), Ig-derived hinges containing a CD2 domain and a CD3 domain, Ig-derived hinges containing a CD2 domain and lacking a CD3 domain, Ig-derived hinges containing a CD3 domain and lacking a CD2 domain, Ig-derived hinges lacking a CD2 domain and lacking a CD3 domain, CD8?-derived hinges, CD28-derived hinges, and CD3?-derived hinges. A CAR provided herein can be designed to include a hinge of any appropriate length. For example, a CAR provided herein can be designed to include a hinge that is from about 3 to about 75 (e.g., from about 3 to about 65, from about 3 to about 50, from about 5 to about 75, from about 10 to about 75, from about 5 to about 50, from about 10 to about 50, from about 10 to about 40, or from about 10 to about 30) amino acid residues in length. In some cases, a linker sequence can be used as a hinge to make a CAR Attorney Docket No.48881-0042WO1 / 05676 described herein. For example, any one of the linker sequences set forth in Example 12 can be used as a hinge of a CAR described herein. In some cases, a CAR provided herein can be designed to include a hinge that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 12 or Example 15. In some cases, a CAR provided herein can be designed to include a hinge that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 12 or Example 15 with one, two, three, four, five, six, seven, eight, nine, or ten amino acid deletions, additions, substitutions, or combinations thereof. In some cases, a CAR provided herein can be designed to include a hinge that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 12 or Example 15 with two or less, three or less, four or less, five or less, six or less, seven or less, eight or less, nine or less, or ten or less amino acid deletions, additions, substitutions, or combinations thereof. A CAR provided herein can be designed to include any appropriate transmembrane domain. For example, the transmembrane domain of a CAR provided herein can be, without limitation, a CD3? transmembrane domain, a CD4 transmembrane domain, a CD8? transmembrane domain, a CD28 transmembrane domain, and a 4-1BB transmembrane domain. In some cases, a CAR provided herein can be designed to include a transmembrane domain that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 16. In some cases, a CAR provided herein can be designed to include a transmembrane domain that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 16 with one, two, three, four, five, six, seven, eight, nine, or ten amino acid deletions, additions, substitutions, or combinations thereof. In some cases, a CAR provided herein can be designed to include a transmembrane domain that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 16 with two or less, three or less, four or less, five or less, six or less, seven or less, eight or less, nine or less, or ten or less amino acid deletions, additions, substitutions, or combinations thereof. A CAR provided herein can be designed to include one or more intracellular signaling domains. For example, a CAR provided herein can be designed to include one, Attorney Docket No.48881-0042WO1 / 05676 two, three, or four intracellular signaling domains. Any appropriate intracellular signaling domain or combination of intracellular signaling domains can be used to make a CAR described herein. Examples of intracellular signaling domains that can be used to make a CAR described herein include, without limitation, CD3? intracellular signaling domains, CD27 intracellular signaling domains, CD28 intracellular signaling domains, OX40 (CD134) intracellular signaling domains, 4-1BB (CD137) intracellular signaling domains, CD278 intracellular signaling domains, DAP10 intracellular signaling domains, and DAP12 intracellular signaling domains. In some cases, a CAR described herein can be designed to be a first generation CAR having a CD3? intracellular signaling domain. In some cases, a CAR described herein can be designed to be a second generation CAR having a CD28 intracellular signaling domain followed by a CD3? intracellular signaling domain. In some cases, a CAR described herein can be designed to be a third generation CAR having (a) a CD28 intracellular signaling domain followed by (b) a CD27 intracellular signaling domain, an OX40 intracellular signaling domains, or a 4-1BB intracellular signaling domain followed by (c) a CD3? intracellular signaling domain. In some cases, a CAR provided herein can be designed to include at least one intracellular signaling domain that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 17. In some cases, a CAR provided herein can be designed to include at least one intracellular signaling domain that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 17 with one, two, three, four, five, six, seven, eight, nine, or ten amino acid deletions, additions, substitutions, or combinations thereof, provided that that intracellular signaling domain has at least some activity to activate intracellular signaling. In some cases, a CAR provided herein can be designed to include at least one intracellular signaling domain that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 17 with two or less, three or less, four or less, five or less, six or less, seven or less, eight or less, nine or less, or ten or less amino acid deletions, additions, substitutions, or combinations thereof, provided that that intracellular signaling domain has at least some activity to activate intracellular signaling. Attorney Docket No.48881-0042WO1 / 05676 In some cases, a CAR targeting a PSCA polypeptide can be designed to include a scFv comprising two sets of three CDRs of an antibody or antigen binding fragment provided herein (e.g., SEQ ID NOs:1-3 and 9-11; SEQ ID NOs:17-19 and SEQ ID NOs:25-27; SEQ ID NOs:33-35 and SEQ ID NOs:41-43; SEQ ID NOs:49-51 and SEQ ID NOs:57-59; SEQ ID NOs:65-67 and SEQ ID NOs:73-75; SEQ ID NOs:81-83 and SEQ ID NOs:89-91; SEQ ID NOs:97-99 and SEQ ID NOs:105-107; or SEQ ID NOs:113-115 and SEQ ID NOs:121-123), followed by a hinge such as a hinge / linker set forth in Example 12 or Example 15 (e.g., an IgG4-derived hinge, a CD8? hinge, or a linker plus IgG4-derived hinge), followed by a transmembrane domain such as a transmembrane domain set forth in Example 16 (e.g., a human CD28 transmembrane domain or a CD8? transmembrane domain), followed by one or more intracellular signaling domains such as one or more intracellular signaling domain set forth in Example 17 (e.g., a human 4-1BB intracellular signaling domain followed by a human CD3? intracellular signaling domain). In some cases, a CAR targeting a PSCA polypeptide can be designed to include a scFv comprising two sets of three CDRs of an antibody or antigen binding fragment provided herein (e.g., SEQ ID NOs:1-3 and 9-11; SEQ ID NOs:17-19 and SEQ ID NOs:25-27; SEQ ID NOs:33-35 and SEQ ID NOs:41-43; SEQ ID NOs:49-51 and SEQ ID NOs:57-59; SEQ ID NOs:65-67 and SEQ ID NOs:73-75; SEQ ID NOs:81-83 and SEQ ID NOs:89-91; SEQ ID NOs:97-99 and SEQ ID NOs:105-107; or SEQ ID NOs:113-115 and SEQ ID NOs:121-123), followed by a hinge such as a hinge / linker set forth in Example 12 or Example 15 (e.g., an IgG4-derived hinge, a CD8? hinge, or a linker plus IgG4-derived hinge), followed by a transmembrane domain such as a transmembrane domain set forth in Example 16 (e.g., a human CD28 transmembrane domain or a CD8? transmembrane domain), followed by one or more intracellular signaling domains such as one or more intracellular signaling domain set forth in Example 17 (e.g., a human CD28 intracellular signaling domain followed by a human CD3? intracellular signaling domain). Examples of such CARs are set forth in Figures 29-44. Attorney Docket No.48881-0042WO1 / 05676 The term “cell engager” as used herein refers to a polypeptide that includes two or more antigen binding domains (e.g., two, three, or four antigen binding domains) and has the ability to link two cells together. Examples of cell engagers include, without limitation, BiTEs, BiKEs, and TriKEs. In general, a cell engager provided herein can be designed to include at least one antigen binding domain having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) and at least one antigen binding domain having the ability to bind to an antigen expressed on the surface of a cell (e.g., a T cell or an NK cell). In some cases, a cell engager described herein can link a PSCA+cell (e.g., a PSCA+cancer cell) to another cell (e.g., a T cell or an NK cell) via the two or more antigen binding domains of the cell engager. An example of a cell engager structure of cell engagers provided herein includes, without limitation, the structure set forth in Figure 3. In some cases, the anti-CD3 scFv depicted in Figure 3 can be replaced with a different antigen binding domain having the ability to bind to an antigen expressed on the surface of a cell (e.g., a T cell or an NK cell). When a cell engager includes an antigen binding domain having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) and two or more other antigen binding domains (e.g., two, three, or four other antigen binding domains), each of those other antigen binding domains can bind to different antigens expressed on the surface of different cell types or can bind to different antigens expressed on the surface of the same cell type. For example, a TriKE can be designed to have a first antigen binding domain having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide), a second antigen binding domain having the ability to bind to a first antigen expressed on the surface of an NK cell (e.g., a CD16 polypeptide such as a CD16a polypeptide), and a third antigen binding domain having the ability to bind to a second antigen expressed on the surface of an NK cell (e.g., an NKG2A polypeptide). As described herein, at least one antigen binding domain of a cell engager provided herein can be designed to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). For example, a cell engager provided herein can be designed to include the components of an antibody, antigen binding fragment, and / or antibody domain described herein (e.g., a combination of CDRs) as an antigen binding domain provided that that Attorney Docket No.48881-0042WO1 / 05676 antigen binding domain has the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). In some examples, a cell engager provided herein can be designed to include an antigen binding domain that includes two sets of three CDRs (e.g., CDR1, CDR2, and CDR3 of a heavy chain and CDR1, CDR2, and CDR3 of a light chain) of an antigen binding fragment. In some examples, a cell engager provided herein can be designed to include an antigen binding domain that includes a single set of three CDRs (e.g., a CDR1, CDR2, and CDR3) of an antibody domain (e.g., a VH domain or a VL domain) provided herein (e.g., a VH domain designed to include one set of three CDRs of a heavy chain provided herein such as SEQ ID NOs:1-3; SEQ ID NOs:17-19 SEQ ID NOs:33-35; SEQ ID NOs:49-51; SEQ ID NOs:65-67; SEQ ID NOs:81-83; SEQ ID NOs:97-99; or SEQ ID NOs:113-115, or a VL domain designed to include one set of three CDRs of a light chain provided herein such as SEQ ID NOs:9-11; SEQ ID NOs:25-27; SEQ ID NOs:41-43; SEQ ID NOs:57-59; SEQ ID NOs:73-75; SEQ ID NOs:89-91; SEQ ID NOs:105-107; or SEQ ID NOs:121-123). In some cases, an antigen binding domain of a cell engager targeting a PSCA polypeptide can be designed to include a VH domain described herein or a scFv described herein (see, e.g., Figures 7-9), or a Fab antibody described herein (see, e.g., Figures 2-6). In some cases, an antigen binding domain of a CAR described herein that has the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can be used as an antigen binding domain of a cell engager that targets PSCA+cells. As described herein, a cell engager can be designed to include at least one antigen binding domain having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) and at least one other antigen binding domain. That at least one other antigen binding domain can have the ability to bind to any appropriate antigen expressed on the surface of a cell. For example, when designing a cell engager such as a BiTE to link a PSCA+cell and a T cell, the cell engager can include an antigen binding domain having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) and an antigen binding domain having the ability to bind to a polypeptide expressed on the surface of a T cell. Examples of polypeptides expressed on the surface of a T cell that Attorney Docket No.48881-0042WO1 / 05676 can be targeted by an antigen binding domain of a cell engager provided herein include, without limitation, CD3 polypeptides. Examples of antigen binding domains having the ability to bind to a polypeptide expressed on the surface of a T cell that can be used to make a cell engager provided herein (e.g., a BiTE) include, without limitation, anti-CD3 scFvs and anti-CD3 VH domains. Additional examples of amino acid sequences that can be used as antigen binding domains having the ability to bind to a polypeptide expressed on the surface of a T cell (e.g., CD3) are described in U.S. Patent No.6,750,325 (see, e.g., the sequence listing of U.S. Patent No.6,750,325). Examples of BiTE structures that can be used to make a BiTE provided herein include, without limitation, those set forth in Example 22. In some cases, a cell engager provided herein can be designed to include an antigen binding domain that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 19. In some cases, a cell engager provided herein can be designed to include an antigen binding domain that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 19 with one, two, three, four, five, six, seven, eight, nine, or ten amino acid deletions, additions, substitutions, or combinations thereof, provided that the antigen binding domain has the ability to bind to a polypeptide expressed on the surface of a T cell. In some cases, a cell engager provided herein can be designed to include an antigen binding domain that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 19 with two or less, three or less, four or less, five or less, six or less, seven or less, eight or less, nine or less, or ten or less amino acid deletions, additions, substitutions, or combinations thereof, provided that the antigen binding domain has the ability to bind to a polypeptide expressed on the surface of a T cell. When designing a cell engager such as a BiKE or a TriKE to link a PSCA+cell and an NK cell, the cell engager can include an antigen binding domain having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) and one or more (e.g., one, two, or three) antigen binding domains having the ability to bind to a polypeptide expressed on the surface of an NK cell. Examples of polypeptides expressed on the surface of an NK cell that can be targeted by an antigen binding domain of a cell engager Attorney Docket No.48881-0042WO1 / 05676 provided herein include, without limitation, CD16 polypeptides (e.g., CD16a polypeptides), NKG2A polypeptides, NKG2D polypeptides, NKp30 polypeptides, NKp44 polypeptides, and NKp46 polypeptides. Examples of antigen binding domains having the ability to bind to a polypeptide expressed on the surface of an NK cell that can be used to make a cell engager provided herein (e.g., a BiKE or TriKE) include, without limitation, anti-CD16a scFvs, anti-NKG2A scFvs, anti-NKG2D scFvs, anti-NKp30 scFvs (see, e.g., BioLegend Catalog #325207), anti-NKp44 scFvs, anti-NKp46 scFvs, anti- CD16a VH domains, anti-NKG2A VH domains, anti-NKG2D VH domains, anti-NKp30 VH domains, anti-NKp44 VH domains, and anti-NKp46 VH domains. Additional examples of amino acid sequences that can be used as antigen binding domains having the ability to bind to a polypeptide expressed on the surface of an NK cell (e.g., CD16, NKG2A, NKG2D, or NKp46) are described in McCall et al. (Mol. Immunol., 36(7):433- 445 (1999); see, e.g., anti-CD16 scFv sequences); International Patent Application Publication No. PCT / US2017 / 048721 (see, e.g., the CDRs and sequence listing for anti- CD16a binding domains); U.S. Patent Application Publication No.2011 / 0052606 (see, e.g., the CDRs and the sequence listing for anti-NKG2A antibodies such as Z199); U.S. Patent Application Publication No.2011 / 0150870 (see, e.g., the CDRs and sequence listing for anti-NKG2D antibodies); U.S. Patent Application Publication No. 2018 / 0369373 (see, e.g., the CDRs and sequence listing for anti-NKp46 antibodies); and U.S. Patent Application Publication No.2017 / 0368169 (see, e.g., the CDRs and sequence listing for anti-NKp46 antibodies). In some cases, a cell engager provided herein can be designed to include an antigen binding domain (e.g., a scFv or VH) that comprises, consists essentially of, or consists of one or more of the amino acid sequences set forth in Example 20. In some cases, a cell engager provided herein can be designed to include an antigen binding domain (e.g., a scFv or VH) that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 20 with one, two, three, four, five, six, seven, eight, nine, or ten amino acid deletions, additions, substitutions, or combinations thereof, provided that the antigen binding domain has the ability to bind to a polypeptide expressed on the surface of an NK cell. In some cases, a cell engager provided herein Attorney Docket No.48881-0042WO1 / 05676 can be designed to include an antigen binding domain (e.g., a scFv or VH) that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 20 with two or less, three or less, four or less, five or less, six or less, seven or less, eight or less, nine or less, or ten or less amino acid deletions, additions, substitutions, or combinations thereof, provided that the antigen binding domain has the ability to bind to a polypeptide expressed on the surface of an NK cell. In some cases, a cell engager provided herein can be designed to include a linker located between each antigen binding domain. Any appropriate linker can be used to design a cell engager provided herein. Examples of linkers that can be used to make a cell engager described herein include, without limitation, the linker sequences set forth in Example 12. A cell engager provided herein can be designed to include a linker of any appropriate length. For example, a cell engager provided herein can be designed to include a linker that is from about 3 to about 100 (e.g., from about 3 to about 90, from about 3 to about 80, from about 3 to about 70, from about 3 to about 60, from about 3 to about 50, from about 3 to about 40, from about 3 to about 30, from about 3 to about 20, from about 3 to about 15, from about 5 to about 100, from about 10 to about 100, from about 20 to about 100, from about 30 to about 100, from about 40 to about 100, from about 50 to about 100, from about 60 to about 100, from about 70 to about 100, from about 10 to about 50, from about 10 to about 40, from about 10 to about 30, from about 10 to about 20, or from about 12 to about 17) amino acid residues in length. In some cases, a cell engager provided herein (e.g., a BiTE) can be designed to include a GGGGSGGGGSGGGGS (SEQ ID NO:135) linker. In some cases, a hinge of a CAR described herein can be used as a linker to make a cell engager described herein. For example, any one of the sequences set forth in Example 15 can be used as a linker of a cell engager described herein. In some cases, a cell engager provided herein can be designed to include a linker that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 12 or Example 15. In some cases, a cell engager provided herein can be designed to include a linker that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 12 or Example 15 with one, two, three, Attorney Docket No.48881-0042WO1 / 05676 four, five, six, seven, eight, nine, or ten amino acid deletions, additions, substitutions, or combinations thereof. In some cases, a cell engager provided herein can be designed to include a linker that comprises, consists essentially of, or consists of one of the amino acid sequences set forth in Example 12 or Example 15 with two or less, three or less, four or less, five or less, six or less, seven or less, eight or less, nine or less, or ten or less amino acid deletions, additions, substitutions, or combinations thereof. In some cases, a cell engager (e.g., a BiTE) targeting a PSCA polypeptide can be designed to include an antigen binding domain comprising two sets of three CDRs of an antibody or antigen binding fragment provided herein (e.g., SEQ ID NOs:1-3 and 9-11; SEQ ID NOs:17-19 and SEQ ID NOs:25-27; SEQ ID NOs:33-35 and SEQ ID NOs:41- 43; SEQ ID NOs:49-51 and SEQ ID NOs:57-59; SEQ ID NOs:65-67 and SEQ ID NOs:73-75; SEQ ID NOs:81-83 and SEQ ID NOs:89-91; SEQ ID NOs:97-99 and SEQ ID NOs:105-107; or SEQ ID NOs:113-115 and SEQ ID NOs:121-123), followed by a linker such as a linker / hinge set forth in Example 12 or Example 15 (e.g., SEQ ID NO:135), followed by an antigen binding domain having the ability to bind to a polypeptide expressed on the surface of a T cell (e.g., an anti-human CD3 scFv) (see, e.g., Figures 64-71). In some cases, a cell engager (e.g., a BiTE) targeting a PSCA polypeptide can be designed to include an IgG (e.g., IgG1) configuration having (a) a heavy chain comprising, consisting essentially of, or consisting of a heavy chain variable domain comprising a set of three CDRs provided herein (e.g., SEQ ID NOs:1-3; SEQ ID NOs:17- 19; SEQ ID NOs:33-35; SEQ ID NOs:49-51; SEQ ID NOs:65-67; SEQ ID NOs:81-83; SEQ ID NOs:97-99; or SEQ ID NOs:113-115), an Ig hinge, and constant domains (e.g., CH1, CH2, and CH3 domains), (b) a light chain comprising, consisting essentially of, or consisting of a light chain variable domain comprising a set of three CDRs provided herein (e.g., SEQ ID NOs:9-11; SEQ ID NOs:25-27; SEQ ID NOs:41-43; SEQ ID NOs:57-59; SEQ ID NOs:73-75; SEQ ID NOs:89-91; SEQ ID NOs:105-107; or SEQ ID NOs:121-123), a constant domain (e.g., a kappa or lambda constant domain), and (c) an antigen binding domain having the ability to bind to a polypeptide expressed on the surface of a T cell (e.g., an anti-human CD3 scFv). Attorney Docket No.48881-0042WO1 / 05676 In some cases, a cell engager (e.g., a BiKE or a TriKE) targeting a PSCA polypeptide can be designed to include an antigen binding domain comprising two sets of three CDRs of an antibody or antigen binding fragment provided herein (e.g., SEQ ID NOs:1-3 and 9-11; SEQ ID NOs:17-19 and SEQ ID NOs:25-27; SEQ ID NOs:33-35 and SEQ ID NOs:41-43; SEQ ID NOs:49-51 and SEQ ID NOs:57-59; SEQ ID NOs:65-67 and SEQ ID NOs:73-75; SEQ ID NOs:81-83 and SEQ ID NOs:89-91; SEQ ID NOs:97- 99 and SEQ ID NOs:105-107; or SEQ ID NOs:113-115 and SEQ ID NOs:121-123), followed by a linker such as a linker / hinge set forth in Example 12 or Example 15 (e.g., SEQ ID NO:135), followed by one or more antigen binding domains having the ability to bind to a polypeptide expressed on the surface of an NK cell (e.g., an anti-human CD16a scFv for a BiKE or an anti-human CD16a scFv and an anti-human NKG2A scFv for a TriKE) (see, e.g., Figures 48-63). In some cases, a cell engager (e.g., a BiKE or a TriKE) targeting a PSCA polypeptide can be designed to include an IgG (e.g., IgG1) configuration having (a) a heavy chain comprising, consisting essentially of, or consisting of a heavy chain variable domain comprising a set of three CDRs provided herein (e.g., SEQ ID NOs:1-3; SEQ ID NOs:17-19; SEQ ID NOs:33-35; SEQ ID NOs:49-51; SEQ ID NOs:65-67; SEQ ID NOs:81-83; SEQ ID NOs:97-99; or SEQ ID NOs:113-115), an Ig hinge, and constant domains (e.g., CH1, CH2, and CH3 domains), (b) a light chain comprising, consisting essentially of, or consisting of a light chain variable domain comprising a set of three CDRs provided herein (e.g., SEQ ID NOs:9-11; SEQ ID NOs:25-27; SEQ ID NOs:41-43; SEQ ID NOs:57-59; SEQ ID NOs:73-75; SEQ ID NOs:89-91; SEQ ID NOs:105-107; or SEQ ID NOs:121-123), a constant domain (e.g., a kappa or lambda constant domain), and (c) an antigen binding domain having the ability to bind to a polypeptide expressed on the surface of a NK cell (e.g., an anti-human CD16a VH domain, an anti-human CD16a scFv, or an anti-human NKG2A scFv). In one embodiment, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (i) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth Attorney Docket No.48881-0042WO1 / 05676 in SEQ ID NO:1 (or a variant of SEQ ID NO:1 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:2 (or a variant of SEQ ID NO:2 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:3 (or a variant of SEQ ID NO:3 with one, two, or three amino acid modifications); and / or (ii) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:9 (or a variant of SEQ ID NO:9 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:10 (or a variant of SEQ ID NO:10 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:11 (or a variant of SEQ ID NO:11 with one, two, or three amino acid modifications). An example of such an antigen binding fragment having these CDRs and the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) includes, without limitation, the Fab set forth in Figures 2A and 2B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) and (a) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:1 (or a variant of SEQ ID NO:1 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:2 (or a variant of SEQ ID NO:2 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:3 (or a variant of SEQ ID NO:3 with one, two, or three amino acid modifications) and / or (b) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:9 (or a variant of SEQ ID NO:9 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:10 (or a variant of SEQ ID NO:10 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:11 (or a variant of SEQ ID NO:11 with one, two, or three amino acid modifications) can include any appropriate framework regions. For example, such a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) can include (a) a heavy chain variable domain that includes a Attorney Docket No.48881-0042WO1 / 05676 framework region 1 having the amino acid sequence set forth in SEQ ID NO:4 (or a variant of SEQ ID NO:4 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:5 (or a variant of SEQ ID NO:5 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:6 (or a variant of SEQ ID NO:6 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:7 (or a variant of SEQ ID NO:7 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications) and / or (b) a light chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:12 (or a variant of SEQ ID NO:12 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:13 (or a variant of SEQ ID NO:13 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:14 (or a variant of SEQ ID NO:14 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:15 (or a variant of SEQ ID NO:15 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications). In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) having any of the CDRs set forth in Figures 2A or 2B can be designed to include framework regions as set forth in Figures 2A and 2B or can be designed to include one or more framework regions from another antibody, antibody fragment, or antibody domain. For example, an Fab or a scFv can be designed to include the six CDRs set forth in Figures 2A and 2B and the framework regions set forth in Figures 2A and 2B except that framework region 1 having the amino acid set forth in SEQ ID NO:4 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:20, a framework region 1 having the amino acid set forth in SEQ ID NO:36, a framework region 1 having the amino acid set forth in SEQ ID NO:52, Attorney Docket No.48881-0042WO1 / 05676 a framework region 1 having the amino acid set forth in SEQ ID NO:68, a framework region 1 having the amino acid set forth in SEQ ID NO:84, a framework region 1 having the amino acid set forth in SEQ ID NO:100, or a framework region 1 having the amino acid set forth in SEQ ID NO:116. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:8 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:16. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:8 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:16. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:8 and / or (b) a light chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:16. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:8, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:1, 2, and 3, and / or (b) a light chain variable domain that includes an amino acid sequence Attorney Docket No.48881-0042WO1 / 05676 having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:16, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:9, 10, and 11. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:8, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:1, 2, and 3, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:16, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:9, 10, and 11. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:8 or the amino acid set forth in SEQ ID NO:8 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions) and / or (b) a light chain variable domain that includes the amino acid sequence set forth in SEQ ID NO:16 or the amino acid set forth in SEQ ID NO:16 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions). For example, an antibody or antigen binding fragment provided herein can have the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide), can include a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:8 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:1, 2, and 3, and can include a light chain variable domain having the amino acid sequence set forth in SEQ ID NO:16 with one, two, three, Attorney Docket No.48881-0042WO1 / 05676 four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:9, 10, and 11. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:1, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:2, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:3, and / or (b) a light chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:9, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:10, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:11. As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:1” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:1, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:1, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:1, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:1 include, without limitation, those set forth in Table 1. Table 1. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:1. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 DYYMT 356 EYYMT 357 s use e e , a a co s s s esse a y o e a o ac seque ce set forth in SEQ ID NO:2” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:2, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:2, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:2, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:2 include, without limitation, those set forth in Table 2. Table 2. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:2. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 YISTSGSTIYYADSVKG 372 YISSSGTTIYYADSVKG 373 t forth in SEQ ID NO:3” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:3, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:3, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:3, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:3 include, without limitation, those set forth in Table 3. Table 3. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:3. Sequence SEQ ID NO: As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:9” is a CDR1 that has zero, one, or two amino acid substitutions Attorney Docket No.48881-0042WO1 / 05676 within SEQ ID NO:9, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:9, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:9, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:9 include, without limitation, those set forth in Table 4. Table 4. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:9. Sequence SEQ ID NO: As used herein, a “CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:10” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:10, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:10, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:10, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA Attorney Docket No.48881-0042WO1 / 05676 polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:10 include, without limitation, those set forth in Table 5. Table 5. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:10. Sequence SEQ ID NO: TASSLQS 395 As used herein, a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:11” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:11, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:11, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:11, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:11 include, without limitation, those set forth in Table 6. Table 6. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:11. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 HQTSSLPLT 406 HQSTSLPLT 407 a o e e o e , a e e.g., a a o y, a ge g ag e , antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (i) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:17 (or a variant of SEQ ID NO:17 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:18 (or a variant of SEQ ID NO:18 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:19 (or a variant of SEQ ID NO:19 with one, two, or three amino acid modifications); and / or (ii) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:25 (or a variant of SEQ ID NO:25 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:26 (or a variant of SEQ ID NO:26 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:27 (or a variant of SEQ ID NO:27 with one, two, or three amino acid modifications). An example of such an antigen binding fragment having these CDRs and the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) includes, without limitation, the Fab set forth in Figures 3A and 3B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) and (a) a heavy chain Attorney Docket No.48881-0042WO1 / 05676 variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:17 (or a variant of SEQ ID NO:17 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:18 (or a variant of SEQ ID NO:18 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:19 (or a variant of SEQ ID NO:19 with one, two, or three amino acid modifications) and / or (b) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:25 (or a variant of SEQ ID NO:25 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:26 (or a variant of SEQ ID NO:26 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:27 (or a variant of SEQ ID NO:27 with one, two, or three amino acid modifications) can include any appropriate framework regions. For example, such a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) can include (a) a heavy chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:20 (or a variant of SEQ ID NO:20 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:21 (or a variant of SEQ ID NO:21 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:22 (or a variant of SEQ ID NO:22 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:23 (or a variant of SEQ ID NO:23 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications) and / or (b) a light chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:28 (or a variant of SEQ ID NO:28 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:29 (or a variant of SEQ ID NO:29 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:30 (or a Attorney Docket No.48881-0042WO1 / 05676 variant of SEQ ID NO:30 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:31 (or a variant of SEQ ID NO:31 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications). In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) having any of the CDRs set forth in Figures 3A or 3B can be designed to include framework regions as set forth in Figures 3A and 3B or can be designed to include one or more framework regions from another antibody, antibody fragment, or antibody domain. For example, an Fab or a scFv can be designed to include the six CDRs set forth in Figures 3A and 3B and the framework regions set forth in Figures 3A and 3B except that framework region 1 having the amino acid set forth in SEQ ID NO:20 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:4, a framework region 1 having the amino acid set forth in SEQ ID NO:36, a framework region 1 having the amino acid set forth in SEQ ID NO:52, a framework region 1 having the amino acid set forth in SEQ ID NO:68, a framework region 1 having the amino acid set forth in SEQ ID NO:84, a framework region 1 having the amino acid set forth in SEQ ID NO:100, or a framework region 1 having the amino acid set forth in SEQ ID NO:116. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:24 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:32. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:24 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, Attorney Docket No.48881-0042WO1 / 05676 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:32. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:24 and / or (b) a light chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:32. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:24, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:17, 18, and 19, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:32, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:25, 26, and 27. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:24, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:17, 18, and 19, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:32, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:25, 26, and 27. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:24 or the Attorney Docket No.48881-0042WO1 / 05676 amino acid set forth in SEQ ID NO:24 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions) and / or (b) a light chain variable domain that includes the amino acid sequence set forth in SEQ ID NO:32 or the amino acid set forth in SEQ ID NO:32 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions). For example, an antibody or antigen binding fragment provided herein can have the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide), can include a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:24 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:17, 18, and 19, and can include a light chain variable domain having the amino acid sequence set forth in SEQ ID NO:32 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:25, 26, and 27. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:17, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:18, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:19, and / or (b) a light chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:25, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:26, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in Attorney Docket No.48881-0042WO1 / 05676 SEQ ID NO:27. As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:17” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:17, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:17, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:17, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:17 include, without limitation, those set forth in Table 7. Table 7. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:17. Sequence SEQ ID NO: As used herein, a “CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:18” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:18, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:18, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:18, provided that the binder (e.g., an Attorney Docket No.48881-0042WO1 / 05676 antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:18 include, without limitation, those set forth in Table 8. Table 8. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:18. Sequence SEQ ID NO: YLSSSGSTIYYADSVKG 425 As used herein, a “CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:19” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:19, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:19, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:19, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:19 include, without limitation, those set forth in Table 9. Table 9. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:19. Attorney Docket No.48881-0042WO1 / 05676 Sequence SEQ ID NO: PLKWGMDV 435 s used ere n, a C t at cons sts essent a y o t e amno acd sequence set forth in SEQ ID NO:25” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:25, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:25, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:25, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:25 include, without limitation, those set forth in Table 10. Table 10. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:25. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 KASQSISSYLD 450 RASESISSYLN 451 , et forth in SEQ ID NO:26” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:26, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:26, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:26, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:26 include, without limitation, those set forth in Table 11. Table 11. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:26. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 As used herein, a “CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:27” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:27, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:27, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:27, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:27 include, without limitation, those set forth in Table 12. Table 12. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:27. Sequence SEQ ID NO: In another embodiment, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (i) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:33 (or a variant of SEQ ID NO:33 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:34 (or a Attorney Docket No.48881-0042WO1 / 05676 variant of SEQ ID NO:34 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:35 (or a variant of SEQ ID NO:35 with one, two, or three amino acid modifications); and / or (ii) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:41 (or a variant of SEQ ID NO:41 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:42 (or a variant of SEQ ID NO:42 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:43 (or a variant of SEQ ID NO:43 with one, two, or three amino acid modifications). An example of such an antigen binding fragment having these CDRs and the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) includes, without limitation, the Fab set forth in Figures 4A and 4B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) and (a) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:33 (or a variant of SEQ ID NO:33 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:34 (or a variant of SEQ ID NO:34 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:35 (or a variant of SEQ ID NO:35 with one, two, or three amino acid modifications) and / or (b) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:41 (or a variant of SEQ ID NO:41 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:42 (or a variant of SEQ ID NO:42 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:43 (or a variant of SEQ ID NO:43 with one, two, or three amino acid modifications) can include any appropriate framework regions. For example, such a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) can include (a) a heavy chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:36 (or a variant of SEQ ID NO:36 with one, two, three, four, five, six, seven, eight, nine, ten, or Attorney Docket No.48881-0042WO1 / 05676 more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:37 (or a variant of SEQ ID NO:37 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:38 (or a variant of SEQ ID NO:38 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:39 (or a variant of SEQ ID NO:39 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications) and / or (b) a light chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:44 (or a variant of SEQ ID NO:44 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:45 (or a variant of SEQ ID NO:45 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:46 (or a variant of SEQ ID NO:46 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:47 (or a variant of SEQ ID NO:47 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications). In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) having any of the CDRs set forth in Figures 4A or 4B can be designed to include framework regions as set forth in Figures 4A and 4B or can be designed to include one or more framework regions from another antibody, antibody fragment, or antibody domain. For example, an Fab or a scFv can be designed to include the six CDRs set forth in Figures 4A and 4B and the framework regions set forth in Figures 4A and 4B except that framework region 1 having the amino acid set forth in SEQ ID NO:36 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:4, a framework region 1 having the amino acid set forth in SEQ ID NO:20, a framework region 1 having the amino acid set forth in SEQ ID NO:52, a framework region 1 having the amino acid set forth in SEQ ID NO:68, a framework region 1 having the amino acid set forth in SEQ ID NO:84, a framework region 1 having Attorney Docket No.48881-0042WO1 / 05676 the amino acid set forth in SEQ ID NO:100, or a framework region 1 having the amino acid set forth in SEQ ID NO:116. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:40 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:48. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:40 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:48. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:40 and / or (b) a light chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:48. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:40, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:33, 34, and 35, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:48, provided that the light chain variable domain includes the amino acid sequences set forth Attorney Docket No.48881-0042WO1 / 05676 in SEQ ID NOs:41, 42, and 43. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:40, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:33, 34, and 35, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:48, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:41, 42, and 43. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:40 or the amino acid set forth in SEQ ID NO:40 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions) and / or (b) a light chain variable domain that includes the amino acid sequence set forth in SEQ ID NO:48 or the amino acid set forth in SEQ ID NO:48 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions). For example, an antibody or antigen binding fragment provided herein can have the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide), can include a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:40 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:33, 34, and 35, and can include a light chain variable domain having the amino acid sequence set forth in SEQ ID NO:48 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the light Attorney Docket No.48881-0042WO1 / 05676 chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:41, 42, and 43. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:33, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:34, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:35, and / or (b) a light chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:41, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:42, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:43. As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:33” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:33, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:33, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:33, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:33 include, without limitation, those set forth in Table 13. Table 13. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:33. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 EYYMT 477 DYYMH 478 , y q et forth in SEQ ID NO:34” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:34, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:34, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:34, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:34 include, without limitation, those set forth in Table 14. Table 14. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:34. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 YISSSGTTIYYADSVKG 493 YISSSGSTIYYADTVKG 494 t forth in SEQ ID NO:35” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:35, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:35, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:35, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:35 include, without limitation, those set forth in Table 15. Table 15. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:35. Sequence SEQ ID NO: As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:41” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:41, that has zero, one, two, three, four, or five amino acid residues Attorney Docket No.48881-0042WO1 / 05676 directly preceding SEQ ID NO:41, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:41, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:41 include, without limitation, those set forth in Table 16. Table 16. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:41. Sequence SEQ ID NO: KA I YL As used herein, a “CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:42” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:42, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:42, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:42, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:42 include, without limitation, those set forth in Table 17. Attorney Docket No.48881-0042WO1 / 05676 Table 17. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:42. Sequence SEQ ID NO: TASSLQS 515 As used herein, a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:43” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:43, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:43, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:43, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:43 include, without limitation, those set forth in Table 18. Table 18. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:43. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 HQSESLPLT 528 HQSNTLPLT 529 , .g., y, g g g , antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (i) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:49 (or a variant of SEQ ID NO:49 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:50 (or a variant of SEQ ID NO:50 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:51 (or a variant of SEQ ID NO:51 with one, two, or three amino acid modifications); and / or (ii) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:57 (or a variant of SEQ ID NO:57 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:58 (or a variant of SEQ ID NO:58 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:59 (or a variant of SEQ ID NO:59 with one, two, or three amino acid modifications). An example of such an antigen binding fragment having these CDRs and the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) includes, without limitation, the Fab set forth in Figures 5A and 5B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) and (a) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:49 (or a variant of SEQ ID NO:49 with one, two, or three amino acid modifications), Attorney Docket No.48881-0042WO1 / 05676 a CDR2 having the amino acid sequence set forth in SEQ ID NO:50 (or a variant of SEQ ID NO:50 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:51 (or a variant of SEQ ID NO:51 with one, two, or three amino acid modifications) and / or (b) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:57 (or a variant of SEQ ID NO:57 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:58 (or a variant of SEQ ID NO:58 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:59 (or a variant of SEQ ID NO:59 with one, two, or three amino acid modifications) can include any appropriate framework regions. For example, such a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) can include (a) a heavy chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:52 (or a variant of SEQ ID NO:52 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:53 (or a variant of SEQ ID NO:53 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:54 (or a variant of SEQ ID NO:54 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:55 (or a variant of SEQ ID NO:55 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications) and / or (b) a light chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:60 (or a variant of SEQ ID NO:60 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:61 (or a variant of SEQ ID NO:61 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:62 (or a variant of SEQ ID NO:62 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid Attorney Docket No.48881-0042WO1 / 05676 sequence set forth in SEQ ID NO:63 (or a variant of SEQ ID NO:63 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications). In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) having any of the CDRs set forth in Figures 5A or 5B can be designed to include framework regions as set forth in Figures 5A and 5B or can be designed to include one or more framework regions from another antibody, antibody fragment, or antibody domain. For example, an Fab or a scFv can be designed to include the six CDRs set forth in Figures 5A and 5B and the framework regions set forth in Figures 5A and 5B except that framework region 1 having the amino acid set forth in SEQ ID NO:52 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:4, a framework region 1 having the amino acid set forth in SEQ ID NO:20, a framework region 1 having the amino acid set forth in SEQ ID NO:36, a framework region 1 having the amino acid set forth in SEQ ID NO:68, a framework region 1 having the amino acid set forth in SEQ ID NO:84, a framework region 1 having the amino acid set forth in SEQ ID NO:100, or a framework region 1 having the amino acid set forth in SEQ ID NO:116. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:56 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:64. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:56 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:64. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody Attorney Docket No.48881-0042WO1 / 05676 domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:56 and / or (b) a light chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:64. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:56, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:49, 50, and 51, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:64, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:57, 58, and 59. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:56, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:49, 50, and 51, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:64, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:57, 58, and 59. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:56 or the amino acid set forth in SEQ ID NO:56 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, Attorney Docket No.48881-0042WO1 / 05676 and / or amino acid additions) and / or (b) a light chain variable domain that includes the amino acid sequence set forth in SEQ ID NO:64 or the amino acid set forth in SEQ ID NO:64 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions). For example, an antibody or antigen binding fragment provided herein can have the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide), can include a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:56 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:49, 50, and 51, and can include a light chain variable domain having the amino acid sequence set forth in SEQ ID NO:64 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:57, 58, and 59. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:49, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:50, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:51, and / or (b) a light chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:57, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:58, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:59. As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:49” is a CDR1 that has zero, one, or two amino acid Attorney Docket No.48881-0042WO1 / 05676 substitutions within SEQ ID NO:49, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:49, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:49, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:49 include, without limitation, those set forth in Table 19. Table 19. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:49. Sequence SEQ ID NO: As used herein, a “CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:50” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:50, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:50, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:50, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA Attorney Docket No.48881-0042WO1 / 05676 polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:50 include, without limitation, those set forth in Table 20. Table 20. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:50. Sequence SEQ ID NO: FISSSGSTIVYADSVKG 545 As used herein, a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:51” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:51, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:51, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:51, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:51 include, without limitation, those set forth in Table 21. Table 21. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:51. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 PMRRGMDV 556 PIKRGMDV 557 s use e e , a a co s s s esse a y o e a o ac seque ce set forth in SEQ ID NO:57” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:57, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:57, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:57, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:57 include, without limitation, those set forth in Table 22. Table 22. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:57. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 RASQSISSYMN 572 RTSQSISSYLN 573 t forth in SEQ ID NO:58” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:58, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:58, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:58, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:58 include, without limitation, those set forth in Table 23. Table 23. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:58. Sequence SEQ ID NO: As used herein, a “CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:59” is a CDR3 that has zero, one, or two amino acid substitutions Attorney Docket No.48881-0042WO1 / 05676 within SEQ ID NO:59, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:59, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:59, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:59 include, without limitation, those set forth in Table 24. Table 24. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:59. Sequence SEQ ID NO: In another embodiment, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (i) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:65 (or a variant of SEQ ID NO:65 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:66 (or a variant of SEQ ID NO:66 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:67 (or a variant of SEQ ID Attorney Docket No.48881-0042WO1 / 05676 NO:67 with one, two, or three amino acid modifications); and / or (ii) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:73 (or a variant of SEQ ID NO:73 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:74 (or a variant of SEQ ID NO:74 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:75 (or a variant of SEQ ID NO:75 with one, two, or three amino acid modifications). An example of such an antigen binding fragment having these CDRs and the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) includes, without limitation, the Fab set forth in Figures 6A and 6B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) and (a) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:65 (or a variant of SEQ ID NO:65 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:66 (or a variant of SEQ ID NO:66 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:67 (or a variant of SEQ ID NO:67 with one, two, or three amino acid modifications) and / or (b) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:73 (or a variant of SEQ ID NO:73 with one, two, or three amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:74 (or a variant of SEQ ID NO:74 with one, two, or three amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:75 (or a variant of SEQ ID NO:75 with one, two, or three amino acid modifications) can include any appropriate framework regions. For example, such a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) can include (a) a heavy chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:68 (or a variant of SEQ ID NO:68 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:69 (or a variant of SEQ ID NO:69 with one, two, three, four, Attorney Docket No.48881-0042WO1 / 05676 five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:70 (or a variant of SEQ ID NO:70 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:71 (or a variant of SEQ ID NO:71 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications) and / or (b) a light chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:76 (or a variant of SEQ ID NO:76 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:77 (or a variant of SEQ ID NO:77 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:78 (or a variant of SEQ ID NO:78 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:79 (or a variant of SEQ ID NO:79 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications). In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) having any of the CDRs set forth in Figures 6A or 6B can be designed to include framework regions as set forth in Figures 6A and 6B or can be designed to include one or more framework regions from another antibody, antibody fragment, or antibody domain. For example, an Fab or a scFv can be designed to include the six CDRs set forth in Figures 6A and 6B and the framework regions set forth in Figures 6A and 6B except that framework region 1 having the amino acid set forth in SEQ ID NO:68 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:4, a framework region 1 having the amino acid set forth in SEQ ID NO:20, a framework region 1 having the amino acid set forth in SEQ ID NO:36, a framework region 1 having the amino acid set forth in SEQ ID NO:52, a framework region 1 having the amino acid set forth in SEQ ID NO:84, a framework region 1 having the amino acid set forth in SEQ ID NO:100, or a framework region 1 having the amino acid set forth in SEQ ID NO:116. Attorney Docket No.48881-0042WO1 / 05676 In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:72 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:80. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:72 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:80. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:72 and / or (b) a light chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:80. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:72, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:65, 66, and 67, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:80, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:73, 74, and 75. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can Attorney Docket No.48881-0042WO1 / 05676 include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:72, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:65, 66, and 67, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:80, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:73, 74, and 75. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:72 or the amino acid set forth in SEQ ID NO:72 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions) and / or (b) a light chain variable domain that includes the amino acid sequence set forth in SEQ ID NO:80 or the amino acid set forth in SEQ ID NO:80 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions). For example, an antibody or antigen binding fragment provided herein can have the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide), can include a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:72 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:65, 66, and 67, and can include a light chain variable domain having the amino acid sequence set forth in SEQ ID NO:80 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:73, 74, and 75. Attorney Docket No.48881-0042WO1 / 05676 In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:65, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:66, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:67, and / or (b) a light chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:73, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:74, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:75. As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:65” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:65, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:65, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:65, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:65 include, without limitation, those set forth in Table 25. Table 25. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:65. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 DYYMA 599 EYYMH 600 , et forth in SEQ ID NO:66” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:66, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:66, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:66, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:66 include, without limitation, those set forth in Table 26. Table 26. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:66. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 As used herein, a “CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:67” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:67, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:67, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:67, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:67 include, without limitation, those set forth in Table 27. Table 27. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:67. Sequence SEQ ID NO: As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:73” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:73, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:73, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:73, provided that the binder (e.g., an Attorney Docket No.48881-0042WO1 / 05676 antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:73 include, without limitation, those set forth in Table 28. Table 28. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:73. Sequence SEQ ID NO: KAS SISSYLN 625 As used herein, a “CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:74” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:74, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:74, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:74, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:74 include, without limitation, those set forth in Table 29. Table 29. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:74. Attorney Docket No.48881-0042WO1 / 05676 Sequence SEQ ID NO: TASSLQS 635 s used ere n, a C 3 t at cons sts essent a y o t e amno acd sequence set forth in SEQ ID NO:75” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:75, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:75, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:75, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to an PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:75 include, without limitation, those set forth in Table 30. Table 30. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:75. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 HQSSSLPMT 650 HQSSSLPLS 651 , . ., , , antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (i) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:81 (or a variant of SEQ ID NO:81 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:82 (or a variant of SEQ ID NO:82 with one or two amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:83 (or a variant of SEQ ID NO:83 with one or two amino acid modifications); and / or (ii) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:89 (or a variant of SEQ ID NO:89 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:90 (or a variant of SEQ ID NO:90 with one or two amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:91 (or a variant of SEQ ID NO:91 with one or two amino acid modifications). An example of such a binder having these CDRs and the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) includes, without limitation, the scFv set forth in Figures 7A and 7B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) and (a) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:81 (or a variant of SEQ ID NO:81 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:82 (or a variant of SEQ ID NO:82 with one or two amino acid modifications), and a CDR3 having the amino acid Attorney Docket No.48881-0042WO1 / 05676 sequence set forth in SEQ ID NO:83 (or a variant of SEQ ID NO:83 with one or two amino acid modifications) and / or (b) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:89 (or a variant of SEQ ID NO:89 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:90 (or a variant of SEQ ID NO:90 with one or two amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:91 (or a variant of SEQ ID NO:91 with one or two amino acid modifications) can include any appropriate framework regions. For example, such a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) can include (a) a heavy chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:84 (or a variant of SEQ ID NO:84 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:85 (or a variant of SEQ ID NO:85 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:86 (or a variant of SEQ ID NO:86 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:87 (or a variant of SEQ ID NO:87 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications) and / or (b) a light chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:92 (or a variant of SEQ ID NO:92 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:93 (or a variant of SEQ ID NO:93 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:94 (or a variant of SEQ ID NO:94 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:95 (or a variant of SEQ ID NO:95 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications). Attorney Docket No.48881-0042WO1 / 05676 In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) having any of the CDRs set forth in Figures 7A or 7B can be designed to include framework regions as set forth in Figures 7A and 7B or can be designed to include one or more framework regions from another antibody, antibody fragment, or antibody domain. For example, a scFv can be designed to include the six CDRs set forth in Figures 7A and 7B and the framework regions set forth in Figures 7A and 7B except that framework region 1 having the amino acid set forth in SEQ ID NO:84 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:4 or a framework region 1 having the amino acid set forth in SEQ ID NO:20 or a framework region 1 having the amino acid set forth in SEQ ID NO:36 or a framework region 1 having the amino acid set forth in SEQ ID NO:52 or a framework region 1 having the amino acid set forth in SEQ ID NO:68 or a framework region 1 having the amino acid set forth in SEQ ID NO:100 or a framework region 1 having the amino acid set forth in SEQ ID NO:116. In some cases, an Fab can be designed to include the six CDRs set forth in Figures 7A and 7B and the framework regions set forth in Figures 7A and 7B. In some cases, an Fab can be designed to include the six CDRs set forth in Figures 7A and 7B and the framework regions set forth in Figures 7A and 7B except that framework region 1 having the amino acid set forth in SEQ ID NO:84 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:4 or a framework region 1 having the amino acid set forth in SEQ ID NO:20 or a framework region 1 having the amino acid set forth in SEQ ID NO:36 or a framework region 1 having the amino acid set forth in SEQ ID NO:52 or a framework region 1 having the amino acid set forth in SEQ ID NO:68 or a framework region 1 having the amino acid set forth in SEQ ID NO:100 or a framework region 1 having the amino acid set forth in SEQ ID NO:116. In another example, a scFv can be designed to include the six CDRs set forth in Figures 7A and 7B and the framework regions set forth in Figures 8A and 8B or Figures 9A and 9B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy Attorney Docket No.48881-0042WO1 / 05676 chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:88 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:96. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:88 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:96. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:88 and / or (b) a light chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:96. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:88, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:81, 82, and 83, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:96, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:89, 90, and 91. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:88, provided that the heavy chain variable domain includes the Attorney Docket No.48881-0042WO1 / 05676 amino acid sequences set forth in SEQ ID NOs:81, 82, and 83, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:96, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:89, 90, and 91. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:88 or the amino acid set forth in SEQ ID NO:88 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions) and / or (b) a light chain variable domain that includes the amino acid sequence set forth in SEQ ID NO:96 or the amino acid set forth in SEQ ID NO:96 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions). For example, an antibody or antigen binding fragment provided herein can have the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide), can include a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:88 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:81, 82, and 83, and can include a light chain variable domain having the amino acid sequence set forth in SEQ ID NO:96 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:89, 90, and 91. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy Attorney Docket No.48881-0042WO1 / 05676 chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:81, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:82, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:83, and / or (b) a light chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:89, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:90, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:91. As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:81” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:81, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:81, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:81, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:81 include, without limitation, those set forth in Table 31. Table 31. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:81. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 SYAID 662 EYAIT 663 t forth in SEQ ID NO:82” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:82, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:82, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:82, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:82 include, without limitation, those set forth in Table 32. Table 32. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:82. Sequence SEQ ID NO: As used herein, a “CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:83” is a CDR3 that has zero, one, or two amino acid substitutions Attorney Docket No.48881-0042WO1 / 05676 within SEQ ID NO:83, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:83, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:83, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:83 include, without limitation, those set forth in Table 33. Table 33. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:83. Sequence SEQ ID NO: As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:89” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:89, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:89, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:89, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA Attorney Docket No.48881-0042WO1 / 05676 polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:89 include, without limitation, those set forth in Table 34. Table 34. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:89. Sequence SEQ ID NO: KASQSVSSSNLA 685 As used herein, a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:90” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:90, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:90, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:90, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:90 include, without limitation, those set forth in Table 35. Table 35. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:90. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 GGSTRAT 696 GATTRAT 697 s use e e , a a co s s s esse a y o e a o ac seque ce set forth in SEQ ID NO:91” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:91, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:91, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:91, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:91 include, without limitation, those set forth in Table 36. Table 36. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:91. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 QQYGSSIS 712 QQYGSSIA 713 antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (i) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:97 (or a variant of SEQ ID NO:97 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:98 (or a variant of SEQ ID NO:982 with one or two amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:99 (or a variant of SEQ ID NO:99 with one or two amino acid modifications); and / or (ii) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:105 (or a variant of SEQ ID NO:105 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:106 (or a variant of SEQ ID NO:106 with one or two amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:107 (or a variant of SEQ ID NO:107 with one or two amino acid modifications). An example of such a binder having these CDRs and the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) includes, without limitation, the scFv set forth in Figures 8A and 8B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) and (a) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:97 (or a variant of SEQ ID NO:97 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:98 (or a variant of SEQ ID NO:98 with one or two amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:99 (or a variant of SEQ ID NO:99 with one or two amino acid modifications) and / or (b) a light chain variable domain having a CDR1 Attorney Docket No.48881-0042WO1 / 05676 having the amino acid sequence set forth in SEQ ID NO:105 (or a variant of SEQ ID NO:105 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:106 (or a variant of SEQ ID NO:106 with one or two amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:107 (or a variant of SEQ ID NO:107 with one or two amino acid modifications) can include any appropriate framework regions. For example, such a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) can include (a) a heavy chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:100 (or a variant of SEQ ID NO:100 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:101 (or a variant of SEQ ID NO:101 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:102 (or a variant of SEQ ID NO:102 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:103 (or a variant of SEQ ID NO:103 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications) and / or (b) a light chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:108 (or a variant of SEQ ID NO:108 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:109 (or a variant of SEQ ID NO:109 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:110 (or a variant of SEQ ID NO:110 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:111 (or a variant of SEQ ID NO:111 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications). In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) having any of the CDRs set forth in Attorney Docket No.48881-0042WO1 / 05676 Figures 8A or 8B can be designed to include framework regions as set forth in Figures 8A and 8B or can be designed to include one or more framework regions from another antibody, antibody fragment, or antibody domain. For example, a scFv can be designed to include the six CDRs set forth in Figures 8A and 8B and the framework regions set forth in Figures 8A and 8B except that framework region 1 having the amino acid set forth in SEQ ID NO:100 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:4 or a framework region 1 having the amino acid set forth in SEQ ID NO:20 or a framework region 1 having the amino acid set forth in SEQ ID NO:36 or a framework region 1 having the amino acid set forth in SEQ ID NO:52 or a framework region 1 having the amino acid set forth in SEQ ID NO:68 or a framework region 1 having the amino acid set forth in SEQ ID NO:84 or a framework region 1 having the amino acid set forth in SEQ ID NO:116. In some cases, an Fab can be designed to include the six CDRs set forth in Figures 8A and 8B and the framework regions set forth in Figures 8A and 8B. In some cases, an Fab can be designed to include the six CDRs set forth in Figures 8A and 8B and the framework regions set forth in Figures 8A and 8B except that framework region 1 having the amino acid set forth in SEQ ID NO:100 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:4 or a framework region 1 having the amino acid set forth in SEQ ID NO:20 or a framework region 1 having the amino acid set forth in SEQ ID NO:36 or a framework region 1 having the amino acid set forth in SEQ ID NO:52 or a framework region 1 having the amino acid set forth in SEQ ID NO:68 or a framework region 1 having the amino acid set forth in SEQ ID NO:84 or a framework region 1 having the amino acid set forth in SEQ ID NO:116. In another example, a scFv can be designed to include the six CDRs set forth in Figures 8A and 8B and the framework regions set forth in Figures 7A and 7B or Figures 9A and 9B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:104 and / or (b) a light chain Attorney Docket No.48881-0042WO1 / 05676 variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:112. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:104 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:112. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:104 and / or (b) a light chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:112. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:104, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:97, 98, and 99, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:112, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:105, 106, and 107. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:104, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:97, 98, and 99, and / or (b) a light chain variable domain that includes an amino acid sequence having Attorney Docket No.48881-0042WO1 / 05676 at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:112, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:105, 106, and 107. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:104 or the amino acid set forth in SEQ ID NO:104 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions) and / or (b) a light chain variable domain that includes the amino acid sequence set forth in SEQ ID NO:112 or the amino acid set forth in SEQ ID NO:112 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions). For example, an antibody or antigen binding fragment provided herein can have the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide), can include a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:104 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:97, 98, and 99, and can include a light chain variable domain having the amino acid sequence set forth in SEQ ID NO:112 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:105, 106, and 107. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:97, (ii) a CDR2 that Attorney Docket No.48881-0042WO1 / 05676 comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:98, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:99, and / or (b) a light chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:105, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:106, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:107. As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:97” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:97, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:97, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:97, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:97 include, without limitation, those set forth in Table 37. Table 37. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:97. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 GYYMA 724 t forth in SEQ ID NO:98” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:98, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:98, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:98, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:98 include, without limitation, those set forth in Table 38. Table 38. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:98. Sequence SEQ ID NO: As used herein, a “CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:99” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:99, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:99, and / or that has zero, one, two, three, four, or five Attorney Docket No.48881-0042WO1 / 05676 amino acid residues directly following SEQ ID NO:99, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:99 include, without limitation, those set forth in Table 39. Table 39. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:99. Sequence SEQ ID NO: ATRHAFDI 735 As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:105” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:105, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:105, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:105, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:105 include, without limitation, those set forth in Table 40. Attorney Docket No.48881-0042WO1 / 05676 Table 40. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:105. Sequence SEQ ID NO: SRSSGSIASNYVQ 745 As used herein, a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:106” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:106, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:106, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:106, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:106 include, without limitation, those set forth in Table 41. Table 41. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:106. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 EDNQKPS 759 EDNQRPT 760 , et forth in SEQ ID NO:107” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:107, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:107, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:107, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:107 include, without limitation, those set forth in Table 42. Table 42. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:107. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 In another embodiment, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (i) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:113 (or a variant of SEQ ID NO:113 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:114 (or a variant of SEQ ID NO:114 with one or two amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:115 (or a variant of SEQ ID NO:115 with one or two amino acid modifications); and / or (ii) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:121 (or a variant of SEQ ID NO:121 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:122 (or a variant of SEQ ID NO:122 with one or two amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:123 (or a variant of SEQ ID NO:123 with one or two amino acid modifications). An example of such a binder having these CDRs and the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) includes, without limitation, the scFv set forth in Figures 9A and 9B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) and (a) a heavy chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:113 (or a variant of SEQ ID NO:113 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:114 (or a variant of SEQ ID NO:114 with one or two amino acid modifications), and a CDR3 having the amino acid sequence set forth in SEQ ID NO:115 (or a variant of SEQ ID NO:115 with one or two amino acid modifications) and / or (b) a light chain variable domain having a CDR1 having the amino acid sequence set forth in SEQ ID NO:121 (or a variant of SEQ ID NO:121 with one or two amino acid modifications), a CDR2 having the amino acid sequence set forth in SEQ ID NO:122 (or a variant of SEQ ID NO:122 with one or two Attorney Docket No.48881-0042WO1 / 05676 amino acid modifications), and a CDR3 having the amino acid sequence set forth SEQ ID NO:123 (or a variant of SEQ ID NO:123 with one or two amino acid modifications) can include any appropriate framework regions. For example, such a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) can include (a) a heavy chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:116 (or a variant of SEQ ID NO:116 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:117 (or a variant of SEQ ID NO:117 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:118 (or a variant of SEQ ID NO:118 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:119 (or a variant of SEQ ID NO:119 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications) and / or (b) a light chain variable domain that includes a framework region 1 having the amino acid sequence set forth in SEQ ID NO:124 (or a variant of SEQ ID NO:124 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 2 having the amino acid sequence set forth in SEQ ID NO:125 (or a variant of SEQ ID NO:125 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), a framework region 3 having the amino acid sequence set forth in SEQ ID NO:126 (or a variant of SEQ ID NO:126 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications), and a framework region 4 having the amino acid sequence set forth in SEQ ID NO:127 (or a variant of SEQ ID NO:127 with one, two, three, four, five, six, seven, eight, nine, ten, or more amino acid modifications). In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) having any of the CDRs set forth in Figures 9A or 9B can be designed to include framework regions as set forth in Figures 9A and 9B or can be designed to include one or more framework regions from another antibody, antibody fragment, or antibody domain. For example, a scFv can be designed Attorney Docket No.48881-0042WO1 / 05676 to include the six CDRs set forth in Figures 9A and 9B and the framework regions set forth in Figures 9A and 9B except that framework region 1 having the amino acid set forth in SEQ ID NO:116 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:4 or a framework region 1 having the amino acid set forth in SEQ ID NO:20 or a framework region 1 having the amino acid set forth in SEQ ID NO:36 or a framework region 1 having the amino acid set forth in SEQ ID NO:52 or a framework region 1 having the amino acid set forth in SEQ ID NO:68 or a framework region 1 having the amino acid set forth in SEQ ID NO:84 or a framework region 1 having the amino acid set forth in SEQ ID NO:100. In some cases, an Fab can be designed to include the six CDRs set forth in Figures 9A and 9B and the framework regions set forth in Figures 9A and 9B. In some cases, an Fab can be designed to include the six CDRs set forth in Figures 9A and 9B and the framework regions set forth in Figures 9A and 9B except that framework region 1 having the amino acid set forth in SEQ ID NO:116 is replaced with a framework region 1 having the amino acid set forth in SEQ ID NO:4 or a framework region 1 having the amino acid set forth in SEQ ID NO:20 or a framework region 1 having the amino acid set forth in SEQ ID NO:36 or a framework region 1 having the amino acid set forth in SEQ ID NO:52 or a framework region 1 having the amino acid set forth in SEQ ID NO:68 or a framework region 1 having the amino acid set forth in SEQ ID NO:84 or a framework region 1 having the amino acid set forth in SEQ ID NO:100. In another example, a scFv can be designed to include the six CDRs set forth in Figures 9A and 9B and the framework regions set forth in Figures 7A and 7B or Figures 8A and 8B. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:120 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:128. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an Attorney Docket No.48881-0042WO1 / 05676 ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:120 and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:128. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:120 and / or (b) a light chain variable domain that includes an amino acid sequence having 100 percent identity to the amino acid sequence set forth in SEQ ID NO:128. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:120, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:113, 114, and 115, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:128, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:121, 122, and 123. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein can include (a) a heavy chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:120, provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:113, 114, and 115, and / or (b) a light chain variable domain that includes an amino acid sequence having at least 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent identity to the amino acid sequence set forth in SEQ ID NO:128, provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:121, 122, and 123. Attorney Docket No.48881-0042WO1 / 05676 In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:120 or the amino acid set forth in SEQ ID NO:120 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions) and / or (b) a light chain variable domain that includes the amino acid sequence set forth in SEQ ID NO:128 or the amino acid set forth in SEQ ID NO:128 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions). For example, an antibody or antigen binding fragment provided herein can have the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide), can include a heavy chain variable domain having the amino acid sequence set forth in SEQ ID NO:120 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the heavy chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:113, 114, and 115, and can include a light chain variable domain having the amino acid sequence set forth in SEQ ID NO:128 with one, two, three, four, five, six, seven, eight, nine, or 10 amino acid modifications (e.g., amino acid substitutions, amino acid deletions, and / or amino acid additions), provided that the light chain variable domain includes the amino acid sequences set forth in SEQ ID NOs:121, 122, and 123. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can include (a) a heavy chain variable domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:113, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:114, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:115, and / or (b) a light chain variable Attorney Docket No.48881-0042WO1 / 05676 domain comprising (i) a CDR1 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:121, (ii) a CDR2 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:122, and (iii) a CDR3 that comprises, consists essentially of, or consists of the amino acid sequence set forth in SEQ ID NO:123. As used herein, a “CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:113” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:113, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:113, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:113, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:113 include, without limitation, those set forth in Table 43. Table 43. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:113. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 As used herein, a “CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:114” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:114, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:114, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:114, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:114 include, without limitation, those set forth in Table 44. Table 44. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:114. Sequence SEQ ID NO: As used herein, a “CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:115” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:115, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:115, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:115, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an Attorney Docket No.48881-0042WO1 / 05676 ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:115 include, without limitation, those set forth in Table 45. Table 45. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:115. Sequence SEQ ID NO: EVIVGATSSGMDV 795 As used herein, a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:121” is a CDR1 that has zero, one, or two amino acid substitutions within SEQ ID NO:121, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:121, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:121, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR1 that consists essentially of the amino acid sequence set forth in SEQ ID NO:121 include, without limitation, those set forth in Table 46. Table 46. Exemplary CDR1s that consist essentially of the amino acid sequence set forth in SEQ ID NO:121. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 KASQSISRYLN 805 RGSQSISRYLN 806 s use ere n, a t at cons sts essent a y o t e amno ac sequence set forth in SEQ ID NO:122” is a CDR2 that has zero, one, or two amino acid substitutions within SEQ ID NO:122, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:122, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:122, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR2 that consists essentially of the amino acid sequence set forth in SEQ ID NO:122 include, without limitation, those set forth in Table 47. Table 47. Exemplary CDR2s that consist essentially of the amino acid sequence set forth in SEQ ID NO:122. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 GASSLES 821 GASSLQT 822 , t forth in SEQ ID NO:123” is a CDR3 that has zero, one, or two amino acid substitutions within SEQ ID NO:123, that has zero, one, two, three, four, or five amino acid residues directly preceding SEQ ID NO:123, and / or that has zero, one, two, three, four, or five amino acid residues directly following SEQ ID NO:123, provided that the binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) maintains its basic ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of a CDR3 that consists essentially of the amino acid sequence set forth in SEQ ID NO:123 include, without limitation, those set forth in Table 48. Table 48. Exemplary CDR3s that consist essentially of the amino acid sequence set forth in SEQ ID NO:123. Sequence SEQ ID NO: Attorney Docket No.48881-0042WO1 / 05676 When designing a single chain antibody (e.g., a scFv) having a heavy chain variable domain and a light chain variable domain, the two regions can be directly connected or can be connected using any appropriate linker sequence. For example, a heavy chain variable domain can be connected to a light chain variable domain via a linker sequence. Examples of linker sequences that can be used to connect a heavy chain variable domain and a light chain variable domain to create a scFv include, without limitation, those linkers set forth in Example 12. As indicated herein, the amino acid sequences described herein can include amino acid modifications (e.g., the articulated number of amino acid modifications). Such amino acid modifications can include, without limitation, amino acid substitutions, amino acid deletions, amino acid additions, and combinations. In some cases, an amino acid modification can be made to improve the binding and / or contact with an antigen and / or to improve a functional activity of a binder (e.g., an antibody, antigen binding fragment, antibody domain, a CAR, a cell engager, and / or an ADC) provided herein. In some cases, an amino acid substitution within an articulated sequence identifier can be a conservative amino acid substitution. For example, conservative amino acid substitutions can be made by substituting one amino acid residue for another amino acid residue having a similar side chain. Families of amino acid residues having similar side chains can include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), non-polar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta- branched side chains (e.g., threonine, valine, isoleucine), and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). In some cases, an amino acid substitution within an articulated sequence identifier can be a non-conservative amino acid substitution. Non-conservative amino acid substitutions can be made by substituting one amino acid residue for another amino acid residue having a dissimilar side chain. Examples of non-conservative substitutions include, without limitation, substituting (a) a hydrophilic residue (e.g., serine or threonine) for a hydrophobic residue (e.g., leucine, isoleucine, phenylalanine, valine, or Attorney Docket No.48881-0042WO1 / 05676 alanine); (b) a cysteine or proline for any other residue; (c) a residue having a basic side chain (e.g., lysine, arginine, or histidine) for a residue having an acidic side chain (e.g., aspartic acid or glutamic acid); and (d) a residue having a bulky side chain (e.g., phenylalanine) for glycine or other residue having a small side chain. The percent sequence identity between a particular amino acid or nucleic acid sequence and an amino acid or nucleic acid sequence referenced by a particular sequence identification number is determined as follows. First, an amino acid or nucleic acid sequence is compared to the sequence set forth in a particular sequence identification number using the BLAST 2 Sequences (Bl2seq) program from the stand-alone version of BLASTZ containing BLASTN version 2.0.14 and BLASTP version 2.0.14. This stand- alone version of BLASTZ can be obtained from Fish & Richardson’s web site (e.g., www.fr.com / blast / ) or the U.S. government’s National Center for Biotechnology Information web site (www.ncbi.nlm.nih.gov). Instructions explaining how to use the Bl2seq program can be found in the readme file accompanying BLASTZ. Bl2seq performs a comparison between two sequences using either the BLASTN or BLASTP algorithm. BLASTN is used to compare nucleic acid sequences, while BLASTP is used to compare amino acid sequences. To compare two nucleic acid sequences, the options are set as follows: -i is set to a file containing the first nucleic acid sequence to be compared (e.g., C:\seq1.txt); -j is set to a file containing the second nucleic acid sequence to be compared (e.g., C:\seq2.txt); -p is set to blastn; -o is set to any desired file name (e.g., C:\output.txt); -q is set to -1; -r is set to 2; and all other options are left at their default setting. For example, the following command can be used to generate an output file containing a comparison between two sequences: C:\Bl2seq -i c:\seq1.txt -j c:\seq2.txt -p blastn -o c:\output.txt -q -1 -r 2. To compare two amino acid sequences, the options of Bl2seq are set as follows: -i is set to a file containing the first amino acid sequence to be compared (e.g., C:\seq1.txt); -j is set to a file containing the second amino acid sequence to be compared (e.g., C:\seq2.txt); -p is set to blastp; -o is set to any desired file name (e.g., C:\output.txt); and all other options are left at their default setting. For example, the following command can be used to generate an output file containing a comparison between two amino acid sequences: C:\Bl2seq -i c:\seq1.txt -j Attorney Docket No.48881-0042WO1 / 05676 c:\seq2.txt -p blastp -o c:\output.txt. If the two compared sequences share homology, then the designated output file will present those regions of homology as aligned sequences. If the two compared sequences do not share homology, then the designated output file will not present aligned sequences. Once aligned, the number of matches is determined by counting the number of positions where an identical nucleotide or amino acid residue is presented in both sequences. A matched position refers to a position in which an identical nucleotide or amino acid residue occurs at the same position in aligned sequences. The percent sequence identity is determined by dividing the number of matches by the length of the sequence set forth in the identified sequence (e.g., SEQ ID NO:8, SEQ ID NO:16, or SEQ ID NO:24), followed by multiplying the resulting value by 100. For example, an amino acid sequence that has 100 matches when aligned with the sequence set forth in SEQ ID NO:8 is 85 percent identical to the sequence set forth in SEQ ID NO:8 (i.e., 100 ÷ 117 x 100 = 85.47). It is noted that the percent sequence identity value is rounded to the nearest tenth. For example, 78.11, 78.12, 78.13, and 78.14 is rounded down to 78.1, while 78.15, 78.16, 78.17, 78.18, and 78.19 is rounded up to 78.2. It also is noted that the length value will always be an integer. Methods for generating an amino acid sequence variant (e.g., an amino acid sequence that includes one or more modifications with respect to an articulated sequence identifier) can include site-specific mutagenesis or random mutagenesis (e.g., by PCR) of a nucleic acid encoding the antibody or fragment thereof. See, for example, Zoller, Curr. Opin. Biotechnol.3: 348-354 (1992). Both naturally occurring and non-naturally occurring amino acids (e.g., artificially-derivatized amino acids) can be used to generate an amino acid sequence variant provided herein. A representative number of binders (e.g., antibodies, antigen binding fragments, and / or antibody domains) having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) are further described in Table 49. Table 49. Representative number of binders. Attorney Docket No.48881-0042WO1 / 05676 Clone # SEQ ID NOs of SEQ ID NOs of SEQ ID NO of SEQ ID NOs of SEQ ID NOs of SEQ ID NO of (Antibody Heavy Chain Heavy Chain Heavy Chain Light Chain Light Chain Light Chain on CARs, cell engagers, and / or ADCs) provided herein can be produced using any appropriate method. For example, the binders (e.g., antibodies, antigen binding 5 fragments, antibody domains, CARs, and / or cell engagers) provided herein can be produced in recombinant host cells. For example, a nucleic acid encoding a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein can be constructed, introduced into an expression vector, and expressed in suitable host cells. Example 8 is a sequence listing of nucleic acid sequences encoding 10 exemplary binders (e.g., antibodies, antigen binding fragments, and / or antibody domains) described herein. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein can be recombinantly produced in prokaryotic hosts such as E. coli, Bacillus brevis, Bacillus subtilis, Bacillus megaterium, Lactobacillus zeae / casei, or Lactobacillus paracasei. A binder (e.g., an 15antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein also can be recombinantly produced in eukaryotic hosts such as yeast (e.g., Pichia pastoris, Saccharomyces cerevisiae, Hansenula polymorpha, Attorney Docket No.48881-0042WO1 / 05676 Schizosaccharomyces pombe, Schwanniomyces occidentalis, Kluyveromyces lactis, or Yarrowia lipolytica), filamentous fungi of the genera Trichoderma (e.g., T. reesei) and Aspergillus (e.g., A. niger and A. oryzae), protozoa such as Leishmania tarentolae, insect cells, or mammalian cells (e.g., mammalian cell lines such as Chinese hamster ovary (CHO) cells, Per.C6 cells, mouse myeloma NS0 cells, baby hamster kidney (BHK) cells, or human embryonic kidney cell line HEK293). See, for example, the Frenzel et al. reference (Front Immunol., 4:217 (2013)). In some cases, an antigen binding fragment or antibody domain provided herein can be produced by proteolytic digestion of an intact antibody. For example, an antigen binding fragment can be obtained by treating an antibody with an enzyme such as papain or pepsin. Papain digestion of whole antibodies can be used to produce F(ab)2 or Fab fragments, while pepsin digestion of whole antibodies can be used to produce F(ab’)2 or Fab’ fragments. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) provided herein can be substantially pure. The term “substantially pure” as used herein with reference to a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) refers to the binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) as being substantially free of other polypeptides, lipids, carbohydrates, and nucleic acid with which it is naturally associated. Thus, a substantially pure binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) provided herein is any binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) that is removed from its natural environment and is at least 60 percent pure. A substantially pure binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) provided herein can be at least about 65, 70, 75, 80, 85, 90, 95, or 99 percent pure. This document also provides bispecific binders (e.g., bispecific antibodies, bispecific antigen binding fragments, and / or bispecific antibody domains) that bind to two different epitopes with at least one being an epitope of a PSCA polypeptide (e.g., a human PSCA polypeptide). In some cases, a bispecific binder provided herein can be Attorney Docket No.48881-0042WO1 / 05676 designed to bind to two different epitopes of the same PSCA polypeptide (e.g., a human PSCA polypeptide). In some cases, a bispecific binder provided herein can bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) and to an epitope on a different polypeptide (e.g., a CD3 polypeptide). Bispecific binders can be produced by chemically conjugating two different binders (e.g., antibodies, antigen binding fragments, and / or antibody domains) together. Bispecific binders also can be produced by fusing two antibody-producing cells, e.g., hybridomas, to make a hybrid cell line that produces two different heavy and two different light chains within the same cell, which can result in, for example, bispecific IgG molecules. See, Brinkmann and Kontermann, MAbs., 9(2):182-212 (2017). In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein can be fused or conjugated (e.g., covalently or non-covalently attached) to another polypeptide or other moiety to provide a fusion protein or conjugate. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein can be conjugated (e.g., covalently or non-covalently attached) to a polymer (e.g., polyethylene glycol (PEG), polyethylenimine (PEI) modified with PEG (PEI-PEG), and / or polyglutamic acid (PGA) (N-(2-Hydroxypropyl) methacrylamide (HPMA) copolymers), hyaluronic acid, a fluorescent substance, a luminescent substance, a hapten, an enzyme, a metal chelate, a drug, a radioisotope, and / or a cytotoxic agent. Any appropriate method can be used to conjugate (e.g., covalently or non-covalently attach) another polypeptide or other moiety to a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein. For example, another polypeptide or other moiety can be conjugated to a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein using the methods described in U.S. Patent No.8,021,661. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) provided herein can be modified with a moiety that improves its stabilization and / or retention in circulation, for example, in blood, serum, or other tissues by, for example, at least 1.5-, 2-, 5-, 10-, or 50-fold. For example, Attorney Docket No.48881-0042WO1 / 05676 a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) provided herein can be attached (e.g., covalently or non-covalently attached) to a polymer such as a substantially non-antigenic polymer. Examples of substantially non-antigenic polymers that can be used as described herein include, without limitation, polyalkylene oxides and polyethylene oxides. In some cases, a polymer used herein can have any appropriate molecule weight. For example, a polymer having an average molecular weight from about 200 Daltons to about 35,000 Daltons (e.g., from about 1,000 to about 15,000 Daltons or from about 2,000 to about 12,500 Daltons) can be used. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) provided herein can be attached (e.g., covalently or non-covalently) to a water soluble polymer. Examples of water soluble polymers that can be used as described herein include, without limitation, hydrophilic polyvinyl polymers, polyvinylalcohol, polyvinylpyrrolidone, polyalkylene oxide homopolymers, polyethylene glycol (PEG), polypropylene glycols, polyoxyethylenated polyols, and copolymers thereof and / or block copolymers thereof provided that the water solubility of the copolymer or block copolymers is maintained. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) provided herein can be attached (e.g., covalently or non-covalently attached) to one or more polyoxyalkylenes (e.g., polyoxyethylene, polyoxypropylene, or block copolymers of polyoxyethylene and polyoxypropylene), polymethacrylates, carbomers, branched or unbranched polysaccharides, or combinations thereof. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) provided herein can be covalently attached to polyoxyethylene. This document also provides ADCs. The term “ADC” as used herein refers to a conjugate that includes (a) an antigen binding domain and (b) at least one drug covalently linked directly or indirectly to that antigen binding domain. In some cases, an ADC described herein can include (a) an antigen binding domain having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) and (b) at least one drug covalently linked directly or indirectly to that antigen binding domain. Any appropriate binder (e.g., Attorney Docket No.48881-0042WO1 / 05676 an antibody, antigen binding fragment, and / or antibody domain) provided herein and having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can be used as an antigen binding domain to make an ADC described herein. For example, any of the binders set forth in Table 49 can be used to make an ADC having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide). Examples of drugs that can be used to make an ADC described herein include, without limitation, auristatins (e.g., monomethyl auristatin E (MMAE)), mertansine (DM-1), and pyrrolobenzodiazepine (PBD) dimers. Any appropriate ADC linker can be used to covalently attach one or more drugs to an antigen binding domain having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) to form an ADC provided herein. For example, cleavable or non-cleavable ADC linkers can be used to covalently attach one or more drugs to an antigen binding domain having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) to form an ADC provided herein. Examples of ADC linkers can be used to covalently attach one or more drugs to an antigen binding domain having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) to form an ADC provided herein include, without limitation, ADC disulfide linkers, ADC hydrazone linkers, ADC peptide linkers, ADC thioether linkers, and ADC PEG-containing linkers. In some cases, the methods and materials described elsewhere can be used to make an ADC having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) as described herein (see, e.g., International Patent Application Publication No. WO2018058001 and U.S. Patent No.8,436,147). This document also provides nucleic acid molecules (e.g., isolated nucleic acid molecules) having a nucleic acid sequence encoding at least part of a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein. For example, an isolated nucleic acid molecule provided herein can include a nucleic acid sequence encoding a variable domain such as a variable domain as set forth in any one of Figures 2-9. In another example, an isolated nucleic acid molecule provided herein can include a nucleic acid sequence encoding a CAR or cell engager (e.g., a BiTE, BiKE, or TriKE) described herein. A nucleic acid provided herein (e.g., an Attorney Docket No.48881-0042WO1 / 05676 isolated nucleic acid molecule) can be single stranded or double stranded nucleic acid of any appropriate type (e.g., DNA, RNA, or DNA / RNA hybrids). This document also provides vectors (e.g., plasmid vectors or viral vectors) containing one or more nucleic acids provided herein. An example of a plasmid vector that can be designed to include one or more nucleic acids having a nucleic acid sequence encoding at least part of a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein includes, without limitation, phagemids. Examples of viral vectors that can be designed to include one or more nucleic acids having a nucleic acid sequence encoding at least part of a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein include, without limitation, retroviral vectors, parvovirus-based vectors (e.g., adenoviral-based vectors and adeno-associated virus (AAV)-based vectors), lentiviral vectors (e.g., herpes simplex (HSV)-based vectors), poxviral vectors (e.g., vaccinia virus-based vectors and fowlpox virus-based vectors), and hybrid or chimeric viral vectors. For example, a viral vector having an adenoviral backbone with lentiviral components such as those described elsewhere (Zheng et al., Nat. Biotech., 18(2): 176-80 (2000); WO 98 / 22143; WO 98 / 46778; and WO 00 / 17376) or viral vectors having an adenoviral backbone with AAV components such as those described elsewhere (Fisher et al., Hum. Gene Ther., 7:2079-2087 (1996)) can be designed to include one or more nucleic acids having a nucleic acid sequence encoding at least part of a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein. In some cases, a vector (e.g., a plasmid vector or a viral vector) provided herein can include a nucleic acid sequence encoding scFv or antibody domain (e.g., a VH domain) provided herein. In some cases, a vector (e.g., a plasmid vector or a viral vector) provided herein can include a nucleic acid sequence encoding CAR provided herein. In some cases, a vector (e.g., a plasmid vector or a viral vector) provided herein can include a nucleic acid sequence encoding cell engager provided herein. A vector provided herein (e.g., a plasmid vector or viral vector provided herein) can include any appropriate promoter and other regulatory sequence (e.g., transcription Attorney Docket No.48881-0042WO1 / 05676 and translation initiation and termination codons) operably linked the nucleic acid sequence encoding at least part of a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein. In some cases, a promoter used to drive expression can be a constitutive promotor or a regulatable promotor. Examples of regulatable promoters that can be used as described herein include, without limitation, inducible promotors, repressible promotors, and tissue-specific promoters. Examples of viral promotors that can be used as described herein include, without limitation, adenoviral promotors, vaccinia virus promotors, CMV promotors (e.g., immediate early CMV promotors), and AAV promoters. Any appropriate method can be used to make a nucleic acid molecule (or vector such as a plasmid vector or viral vector) having a nucleic acid sequence encoding at least part of a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein. For example, molecule cloning techniques can be used to make a nucleic acid molecule (or vector such as a plasmid vector or viral vector) having a nucleic acid sequence encoding at least part of a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein as described elsewhere (see, e.g., Sambrook et al., Molecular Cloning: A Laboratory Manual, 2nd edition, Cold Spring Harbor Laboratory, NY (1989); and Ausubel et al., Current Protocols in Molecular Biology, Green Publishing Associates and John Wiley & Sons, New York, N.Y. (1994)). This document also provides host cells that include a nucleic acid provided herein (e.g., a nucleic acid having a nucleic acid sequence encoding at least part of a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein). Host cells that can be designed to include one or more nucleic acids provided herein can be prokaryotic cells or eukaryotic cells. Examples of prokaryotic cells that can be designed to include a nucleic acid provided herein include, without limitation, E. coli (e.g., Tb-1, TG-1, DH5?, XL-Blue MRF (Stratagene), SA2821, or Y1090 cells), Bacillus subtilis, Salmonella typhimurium, Serratia marcescens, or Pseudomonas (e.g., P. aerugenosa) cells. Examples of eukaryotic cells that can be designed to include a nucleic acid provided herein include, without limitation, insect cells Attorney Docket No.48881-0042WO1 / 05676 (e.g., Sf9 or Ea4 cells), yeast cells (e.g., S. cerevisiae cells), and mammalian cells (e.g., mouse, rat, hamster, monkey, or human cells). For example, VERO cells, HeLa cells, 3T3 cells, chinese hamster ovary (CHO) cells, W138 BHK cells, COS-7 cells, and MDCK cells can be designed to include a nucleic acid provided herein. Any appropriate method can be used to introduce one or more nucleic acids provided herein (e.g., a vector such as a plasmid vector or viral vector having a nucleic acid sequence encoding at least part of a binder provided herein) into a host cell. For example, calcium chloride- mediated transformation, transduction, conjugation, triparental mating, DEAE, dextran- mediated transfection, infection, membrane fusion with liposomes, high velocity bombardment with DNA-coated microprojectiles, direct microinjection into single cells, electroporation, or combinations thereof can be used to introduce a nucleic acid provided herein into a host cell (see, e.g., Sambrook et al., Molecular Biology: A Laboratory Manual, Cold Spring Harbor Laboratory, NY (1989); Davis et al., Basic Methods in Molecular Biology (1986); and Neumann et al., EMBO J., 1:841 (1982)). In some cases, cells such as T cells, stem cells (e.g., induced pluripotent stem cells or mesenchymal stem cells), or NK cells can be designed to express one or more nucleic acids encoding a CAR described herein. For example, a population of T cells can be infected with viral vectors designed to express nucleic acid encoding a CAR described herein (e.g., a CAR having the ability to bind to a PSCA polypeptide). In some cases, cells such as T cells, stem cells (e.g., induced pluripotent stem cells or mesenchymal stem cells), or NK cells can be designed to express one or more nucleic acids encoding a cell engager described herein. For example, a population of T cells can be infected with viral vectors designed to express nucleic acid encoding a cell engager described herein (e.g., a cell engager having the ability to bind to a PSCA polypeptide). In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager) provided herein can be produced using a method that includes (a) introducing nucleic acid encoding the polypeptide into a host cell; (b) culturing the host cell in culture medium under conditions sufficient to express the polypeptide; (c) harvesting the polypeptide from the cell or culture medium; and (d) Attorney Docket No.48881-0042WO1 / 05676 purifying the polypeptide (e.g., to reach at least 50, 60, 70, 80, 90, 95, 97, 98, or 99 percent purity). In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, cell engager, and / or ADC) provided herein, a nucleic acid provided herein (e.g., nucleic acid encoding an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager provided herein), a vector provided herein (e.g., a viral vector designed to express an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager provided herein), and / or a host cell provided herein (e.g., a host cell designed to express an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager provided herein) can be formulated as a pharmaceutical composition for administration to a mammal (e.g., a human) having cancer to treat that mammal. In some cases, a binder (e.g., an antibody, antigen binding fragment, antibody domain, cell engager, and / or ADC) provided herein, a nucleic acid provided herein (e.g., nucleic acid encoding an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager provided herein), a vector provided herein (e.g., a viral vector designed to express an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager provided herein), and / or a host cell provided herein (e.g., a host cell designed to express an antibody, antigen binding fragment, antibody domain, CAR, and / or cell engager provided herein) can be formulated as a pharmaceutical composition for administration to a mammal (e.g., a human) to reduce the number of cancer cells within the mammal and / or to increase the survival of the mammal suffering from cancer. For example, a binder (e.g., an antibody, antigen binding fragment, antibody domain, cell engager, and / or ADC) provided herein having the ability to bind to a PSCA polypeptide (e.g., a human PSCA polypeptide) can be formulated as a pharmaceutical composition for administration to a mammal (e.g., a human). In some cases, a pharmaceutical composition provided herein can include a pharmaceutically acceptable carrier such as a buffer, a salt, a surfactant, a sugar, a tonicity modifier, or combinations thereof as, for example, described elsewhere (Gervasi et al., Eur. J. Pharmaceutics and Biopharmaceutics, 131:8-24 (2018)). Examples of pharmaceutically acceptable carriers that can be used to make a pharmaceutical composition provided herein include, without Attorney Docket No.48881-0042WO1 / 05676 limitation, water, lactic acid, citric acid, sodium chloride, sodium citrate, sodium succinate, sodium phosphate, a surfactant (e.g., polysorbate 20, polysorbate 80, or poloxamer 188), dextran 40, or a sugar (e.g., sorbitol, mannitol, sucrose, dextrose, or trehalose), or combinations thereof. For example, a pharmaceutical composition designed to include a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, cell engager, and / or ADC) provided herein (or a nucleic acid, a vector, or a host cell provided herein) can be formulated to include a buffer (e.g., an acetate, citrate, histidine, succinate, phosphate, or hydroxymethylaminomethane (Tris) buffer), a surfactant (e.g., polysorbate 20, polysorbate 80, or poloxamer 188), and a sugar such as sucrose. Other ingredients that can be included within a pharmaceutical composition provided herein include, without limitation, amino acids such as glycine or arginine, antioxidants such as ascorbic acid, methionine, or ethylenediaminetetraacetic acid (EDTA), anticancer agents such as enzalutamide, imanitib, gefitinib, erlotini, sunitinib, lapatinib, nilotinib, sorafenib, temsirolimus, everolimus, pazopanib, crizotinib, ruxolitinib, axitinib, bosutinib, cabozantinib, ponatinib, regorafenib, ibrutinib, trametinib, perifosine, bortezomib, carfilzomib, batimastat, ganetespib, obatoclax, navitoclax, taxol, paclitaxel, or bevacizumab, or combinations thereof. For example, a pharmaceutical composition provided herein can be formulated to include one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cells designed to express a CAR having the ability to bind to a PSCA polypeptide, one or more cell engagers, and / or one or more ADCs) provided herein in combination with one or more checkpoint inhibitors such as anti-PD-1 antibodies or PD-1 inhibitors (e.g., cemiplimab, nivolumab, pembrolizumab, JTX-4014, spartalizumab, camrelizumab, sintilimab, tislelizumab, toripalimab, dostarlimab, INCMGA00012, AMP-224, or AMP-514), anti-PD-L1 antibodies or PD-L1 inhibitors (e.g., avelumab, durvalumab, atezolizumab, KN035, CK-301, AUNP12, CA-170, or BMS-986189), and / or anti-CTLA-4 antibodies (e.g., ipilimumab). In some cases, when a pharmaceutical composition is formulated to include one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cells designed to express a CAR having the Attorney Docket No.48881-0042WO1 / 05676 ability to bind to a PSCA polypeptide, one or more cell engagers, and / or one or more ADCs) provided herein, any appropriate concentration of the binder can be used. For example, a pharmaceutical composition provided herein can be formulated to be a liquid that includes from about 1 mg to about 500 mg (e.g., from about 1 mg to about 500 mg, from about 10 mg to about 500 mg, from about 50 mg to about 500 mg, from about 100 mg to about 500 mg, from about 0.5 mg to about 250 mg, from about 0.5 mg to about 150 mg, from about 0.5 mg to about 100 mg, from about 0.5 mg to about 50 mg, from about 1 mg to about 300 mg, from about 2 mg to about 200 mg, from about 10 mg to about 300 mg, from about 25 mg to about 300 mg, from about 50 mg to about 150 mg, or from about 150 mg to about 300 mg) of a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR+cell population, cell engager, and / or ADC) provided herein per mL. In another example, a pharmaceutical composition provided herein can be formulated to be a solid or semi-solid that includes from about 0.5 mg to about 500 mg (e.g., from about 1 mg to about 500 mg, from about 10 mg to about 500 mg, from about 50 mg to about 500 mg, from about 100 mg to about 500 mg, from about 0.5 mg to about 250 mg, from about 0.5 mg to about 150 mg, from about 0.5 mg to about 100 mg, from about 0.5 mg to about 50 mg, from about 1 mg to about 300 mg, from about 10 mg to about 300 mg, from about 25 mg to about 300 mg, from about 50 mg to about 150 mg, or from about 150 mg to about 300 mg) of a binder (e.g., an antibody, antigen binding fragment, antibody domain, cell engager, and / or ADC) provided herein. In some cases, a pharmaceutical composition containing a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein can be formulated as a dosage form with a titer of the binder being from about 1 x 105to about 1 x 1012(e.g., from about 1 x 105to about 1 x 1010, from about 1 x 105to about 1 x 108, from about 1 x 106to about 1 x 1012, from about 1 x 106to about 1 x 1012, from about 1 x 108to about 1 x 1012, from about 1 x 109to about 1 x 1012, from about 1 x 106to about 1 x 1011, or from about 1 x 107to about 1 x 1010). In some cases, when a pharmaceutical composition is formulated to include one or more nucleic acids (e.g., vectors such as viral vectors) encoding at least part of a binder (e.g., an antibody, antigen binding fragment, antibody domain, CAR, and / or cell Attorney Docket No.48881-0042WO1 / 05676 engager) provided herein, any appropriate concentration of the nucleic acid can be used. For example, a pharmaceutical composition provided herein can be formulated to be a liquid that includes from about 0.5 mg to about 500 mg (e.g., from about 1 mg to about 500 mg, from about 10 mg to about 500 mg, from about 50 mg to about 500 mg, from about 100 mg to about 500 mg, from about 0.5 mg to about 250 mg, from about 0.5 mg to about 150 mg, from about 0.5 mg to about 100 mg, from about 0.5 mg to about 50 mg, from about 1 mg to about 300 mg, from about 2 mg to about 200 mg, from about 10 mg to about 300 mg, from about 25 mg to about 300 mg, from about 50 mg to about 150 mg, or from about 150 mg to about 300 mg) of a nucleic acid provided herein per mL. In another example, a pharmaceutical composition provided herein can be formulated to be a solid or semi-solid that includes from about 0.5 mg to about 500 mg (e.g., from about 1 mg to about 500 mg, from about 10 mg to about 500 mg, from about 50 mg to about 500 mg, from about 100 mg to about 500 mg, from about 0.5 mg to about 250 mg, from about 0.5 mg to about 150 mg, from about 0.5 mg to about 100 mg, from about 0.5 mg to about 50 mg, from about 1 mg to about 300 mg, from about 10 mg to about 300 mg, from about 25 mg to about 300 mg, from about 50 mg to about 150 mg, or from about 150 mg to about 300 mg) of a nucleic acid provided herein. In some cases, a pharmaceutical composition designed to include a binder (e.g., an antibody, antigen binding fragment, antibody domain, cell engager, and / or ADC) provided herein can be formulated to include one or more agents capable of reducing aggregation of the binder when formulated. Examples of such agents that can be used as described herein include, without limitation, methionine, arginine, lysine, aspartic acid, glycine, glutamic acid, and combinations thereof. In some cases, one or more of these amino acids can be included within the formulation at a concentration from about 0.5 mM to about 145 mM (e.g., from about 1 mM to about 145 mM, from about 10 mM to about 145 mM, from about 100 mM to about 145 mM, from about 0.5 mM to about 125 mM, from about 0.5 mM to about 100 mM, from about 0.5 mM to about 75 mM, or from about 10 mM to about 100 mM). A pharmaceutical composition provided herein can be in any appropriate form. For example, a pharmaceutical composition provided herein can designed to be a liquid, a Attorney Docket No.48881-0042WO1 / 05676 semi-solid, or a solid. In some cases, a pharmaceutical composition provided herein can be a liquid solution (e.g., an injectable and / or infusible solution), a dispersion, a suspension, a tablet, a pill, a powder, a microemulsion, a liposome, or a suppository. In some cases, a pharmaceutical composition provided herein can be lyophilized. In some cases, a pharmaceutical composition provided herein (e.g., a pharmaceutical composition that includes one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein can be formulated with a carrier or coating designed to protect against rapid release. For example, a pharmaceutical composition provided herein can be formulated as a controlled release formulation or as a regulated release formulation as described elsewhere (U.S. Patent Application Publication Nos. 2019 / 0241667; 2019 / 0233522; and 2019 / 0233498). This document also provides methods for administering a composition (e.g., a pharmaceutical composition provided herein) containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein (or a nucleic acid, vector, or host cell (e.g., CAR+cells) provided herein) to a mammal (e.g., a human). For example, a composition (e.g., a pharmaceutical composition provided herein) containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein (or a nucleic acid, vector, and / or host cell (e.g., CAR+cells) provided herein) can be administered to a mammal (e.g., a human) having cancer to treat that mammal. In some cases, a composition (e.g., a pharmaceutical composition provided herein) containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein (or a nucleic acid, vector, and / or host cell (e.g., CAR+cells) provided herein) can be administered to a mammal (e.g. a human) to reduce the number of cancer cells within the mammal and / or to increase the survival of the mammal suffering from cancer. Attorney Docket No.48881-0042WO1 / 05676 Any appropriate cancer can be treated using a composition (e.g., a pharmaceutical composition provided herein) containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein (or a nucleic acid, vector, or host cell (e.g., CAR+cells) provided herein). For example, a mammal (e.g., a human) having cancer can be treated by administering a composition (e.g., a pharmaceutical composition) containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein to that mammal. Examples of cancers that can be treated as described herein include, without limitation, prostate cancer such as metastatic prostate cancer, bladder cancer, renal cell cancer, pancreatic cancer, and gastric cancer. In some cases, a mammal (e.g., a human) having a PSCA+cancer (e.g., a PSCA+prostate cancer or a PSCA+metastatic prostate cancer) can be administered a composition (e.g., a pharmaceutical composition) containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein to treat that mammal (e.g., to reduce the number of cancer cells within the mammal). Any appropriate method can be used to administer a composition (e.g., a pharmaceutical composition) provided herein to a mammal (e.g., a human). For example, a composition provided herein (e.g., a pharmaceutical composition containing one or more binders provided herein such as one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs provided herein) can be administered to a mammal (e.g., a human) intravenously (e.g., via an intravenous injection or infusion), intratumorally (e.g., via an intratumoral injection), subcutaneously (e.g., via a subcutaneous injection), intraperitoneally (e.g., via an intraperitoneal injection), orally, via inhalation, or intramuscularly (e.g., via intramuscular injection). In some cases, the route and / or mode of administration of a composition (e.g., a pharmaceutical composition provided herein) can be adjusted for the mammal being treated. Attorney Docket No.48881-0042WO1 / 05676 In some cases, an effective amount of a composition containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein (or a nucleic acid, vector, or host cell (e.g., CAR+cells) provided herein) (e.g., a pharmaceutical composition provided herein) can be an amount that reduces the number of cancer cells within a mammal having cancer without producing significant toxicity to the mammal. In some cases, an effective amount of a composition containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein (or a nucleic acid, vector, or host cell (e.g., CAR+cells) provided herein) (e.g., a pharmaceutical composition provided herein) can be an amount that increases the survival time of a mammal having cancer as compared to a control mammal having comparable cancer and not treated with the composition. For example, an effective amount of a binder (e.g., an antibody, antigen binding fragment, antibody domain, cell engager, and / or ADC) provided herein can be from about 0.001 mg / kg to about 100 mg / kg (e.g., from about 0.001 mg / kg to about 90 mg / kg, from about 0.001 mg / kg to about 80 mg / kg, from about 0.001 mg / kg to about 70 mg / kg, from about 0.001 mg / kg to about 60 mg / kg, from about 0.001 mg / kg to about 50 mg / kg, from about 0.001 mg / kg to about 40 mg / kg, from about 0.001 mg / kg to about 30 mg / kg, from about 0.005 mg / kg to about 100 mg / kg, from about 0.01 mg / kg to about 100 mg / kg, from about 0.05 mg / kg to about 100 mg / kg, from about 0.1 mg / kg to about 100 mg / kg, from about 0.5 mg / kg to about 100 mg / kg, from about 1 mg / kg to about 100 mg / kg, from about 5 mg / kg to about 100 mg / kg, from about 0.01 mg / kg to about 25 mg / kg, from about 0.1 mg / kg to about 30 mg / kg, from about 0.15 mg / kg to about 25 mg / kg, from about 0.2 mg / kg to about 20 mg / kg, from about 0.5 mg / kg to about 20 mg / kg, from about 1 mg / kg to about 30 mg / kg, from about 1 mg / kg to about 25 mg / kg, from about 1 mg / kg to about 20 mg / kg, from about 2 mg / kg to about 20 mg / kg, from about 5 mg / kg to about 30 mg / kg, from about 10 mg / kg to about 30 mg / kg, from about 15 mg / kg to about 30 mg / kg, from about 20 mg / kg to about 30 mg / kg, from about 3 mg / kg to about 30 mg / kg, from about 0.5 mg / kg to about 10 mg / kg, from about 1 mg / kg to about 10 mg / kg, from about 1 mg / kg to about 5 Attorney Docket No.48881-0042WO1 / 05676 mg / kg, or from about 1 mg / kg to about 3 mg / kg). The effective amount can remain constant or can be adjusted as a sliding scale or variable dose depending on the mammal’s response to treatment. Various factors can influence the actual effective amount used for a particular application. For example, the severity of cancer when treating a mammal having cancer, the route of administration, the age and general health condition of the mammal, excipient usage, the possibility of co-usage with other therapeutic or prophylactic treatments such as use of other agents (e.g., checkpoint inhibitors), and the judgment of the treating physician may require an increase or decrease in the actual effective amount of a composition provided herein (e.g., a pharmaceutical composition containing one or more binders provided herein) that is administered. In some cases, an effective frequency of administration of a composition containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein (or a nucleic acid, vector, or host cell (e.g., CAR+cells) provided herein) (e.g., a pharmaceutical composition provided herein) can be a frequency that reduces the number of cancer cells within a mammal having cancer without producing significant toxicity to the mammal. In some cases, an effective frequency of administration of a composition containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein (or a nucleic acid, vector, or host cell (e.g., CAR+cells) provided herein) (e.g., a pharmaceutical composition provided herein) can be a frequency that increases the survival time of a mammal having cancer as compared to a control mammal having comparable cancer and not treated with the composition. For example, an effective frequency of administration of a pharmaceutical composition provided herein such as a pharmaceutical composition containing one or more binders provided herein can be from about twice daily to about once a year (e.g., from about twice daily to about once a month, from about twice daily to about once a week, from about once daily to about once a month, or from one once daily to about once a week). In some cases, the frequency of administration of a Attorney Docket No.48881-0042WO1 / 05676 pharmaceutical composition provided herein such as a pharmaceutical composition containing one or more binders provided herein can be daily. The frequency of administration of a pharmaceutical composition provided herein such as a pharmaceutical composition containing one or more binders provided herein can remain constant or can be variable during the duration of treatment. Various factors can influence the actual effective frequency used for a particular application. For example, the severity of the cancer, the route of administration, the age and general health condition of the mammal, excipient usage, the possibility of co-usage with other therapeutic or prophylactic treatments such as use of other agents (e.g., checkpoint inhibitors), and the judgment of the treating physician may require an increase or decrease in the actual effective frequency of administration of a composition provided herein (e.g., a pharmaceutical composition containing one or more binders provided herein). In some cases, an effective duration of administration of a composition containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein (or a nucleic acid, vector, or host cell (e.g., CAR+cells) provided herein) (e.g., a pharmaceutical composition provided herein) can be a duration that reduces the number of cancer cells within a mammal without producing significant toxicity to the mammal. In some cases, an effective duration of administration of a composition containing one or more binders (e.g., one or more antibodies, one or more antigen binding fragments, one or more antibody domains, one or more cell engagers, and / or one or more ADCs) provided herein (or a nucleic acid, vector, or host cell (e.g., CAR+cells) provided herein) (e.g., a pharmaceutical composition provided herein) can be a duration that increases the survival time of a mammal having cancer as compared to a control mammal having comparable cancer and not treated with the composition. For example, an effective duration of administration of a pharmaceutical composition provided herein such as a pharmaceutical composition containing one or more binders provided herein can vary from a single time point of administration to several weeks to several months (e.g., 4 to 12 weeks). Multiple factors can influence the actual effective duration used for a particular application. For example, the severity of the cancer, the Attorney Docket No.48881-0042WO1 / 05676 route of administration, the age and general health condition of the mammal, excipient usage, the possibility of co-usage with other therapeutic or prophylactic treatments such as use of other agents (e.g., checkpoint inhibitors), and the judgment of the treating physician may require an increase or decrease in the actual effective duration of administration of a composition provided herein (e.g., a pharmaceutical composition containing one or more binders provided herein). In some cases, a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein can be used to detect the presence or absence of a PSCA polypeptide (e.g., a human PSCA polypeptide) in vitro, in situ, or in vivo (e.g., in vivo imaging within a mammal such as a human). For example, a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein can be designed to include a label (e.g., a covalently attached radioactive, enzymatic, colorimetric, or fluorescent label). The labelled binder can be used to detect the presence or absence of a PSCA polypeptide (e.g., a human PSCA polypeptide) within a biological sample in vitro. Examples of biological samples that can be assessed using a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein include, without limitation, serum samples, plasma samples, tissue samples, biopsy samples, cell line samples, and tissue culture samples. In some cases, a biological sample that can be assessed as described herein can include mammalian body tissues and / or cells such as leukocytes, ovary tissue or cells, prostate tissue or cells, heart tissue or cells, placenta tissue or cells, pancreas tissue or cells, liver tissue or cells, spleen tissue or cells, lung tissue or cells, breast tissue or cells, head and neck tissue or cells, endometrium tissue or cells, colon tissue or cells, colorectal tissue or cells, cervix tissue or cells, stomach tissue or cells, or umbilical tissue or cells that may express a PSCA polypeptide (e.g., a human PSCA polypeptide). In some cases, a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein can be immobilized, e.g., on a support, and retention of a PSCA polypeptide (e.g., a human PSCA polypeptide) from a biological sample on the support can be detected, and / or vice versa. In some cases, a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein can be used in applications such as fluorescence polarization, microscopy, ELISA, Attorney Docket No.48881-0042WO1 / 05676 centrifugation, chromatography, and / or cell sorting (e.g., fluorescence activated cell sorting). In some cases, a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein containing a label (e.g., a covalently attached radioactive label) can be used to detect the presence or absence of a PSCA polypeptide (e.g., a human PSCA polypeptide) within a mammal (e.g., a human). For example, a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein that is labelled (e.g., covalently labelled) with a radiolabel or an MRI detectable label can be administered to a mammal (e.g., a human), and that mammal can be assessed using a means for detecting the detectable label. In some cases, a mammal can be scanned to evaluate the location(s) of a labelled binder provided herein within the mammal. For example, the mammal can be imaged using NMR or other tomographic techniques. Examples of labels that can be attached (e.g., covalently or non-covalently attached) to a binder (e.g., an antibody, antigen binding fragment, and / or antibody domain) provided herein include, without limitation, radiolabels such as131I,111In,123I,99mTc,32P,33P,125I,3H,14C, and188Rh, fluorescent labels such as fluorescein and rhodamine, nuclear magnetic resonance active labels, positron emitting isotopes detectable by a positron emission tomography (“PET”) scanner, chemiluminescers such as luciferin, and enzymatic markers such as a peroxidase or a phosphatase. In some cases, short-range radiation emitters such as isotopes detectable by short-range detector probes can be used. The invention will be further described in the following examples, which do not limit the scope of the invention described in the claims. EXAMPLES Example 1 – Obtaining binders having the ability to bind to a human PSCA polypeptide Large phage displayed antibody libraries were panned and screened to identify binders that bind to a human PSCA polypeptide using the underlined amino acid Attorney Docket No.48881-0042WO1 / 05676 sequence set forth in SEQ ID NO:129 as shown in Example 6. To identify such binders, a polypeptide having amino acid residues 12 to 87 of human PSCA polypeptide set forth in Example 6 (the 114 isoform) was fused to the AviTag sequence at the C-terminus of the PSCA sequence, and the PSCA-AviTag polypeptide was used for panning of human Fab and scFv phage-displayed libraries. Five Fabs (Clones #1, #2, #3, #4, and #5; Figures 2, 3, 4, 5, and 6) were identified, and three scFvs (Clones #6, #7, and 8#; Figures 7, 8, and 9) were identified. Clones #4 and #5 were obtained by phage display based affinity maturation screening. Binding affinity and specificity to a human PSCA polypeptide were tested using an ELISA and flow cytometry. Clones #4 and #5 exhibited high affinity binding to a human PSCA polypeptide having EC50 values of 4 nM and 0.4 nM, respectively. Clone F12 (Clone #5) bound to PC-3 cells displaying human PSCA, but did not bind to PC-3 cells lacking expression of human PSCA, demonstrating that it can bind to PSCA polypeptides present on cells (see, e.g., Figures 4-6). Specificity characterization and epitope mapping of the affinity enhanced Clone #5 was performed. Clone #5 binding to 5300 human membrane proteins was tested by the proteomic membrane array. Results showed Clone #5 only binds to PSCA without any discernable binding to other human proteins. Epitope mapping by the peptide array method was performed using Clone #5, in which the overlapping peptides consisting of 7-11 amino acids were printed on a chip followed by addition of Clone #5 and detection of antibody for observing binding. Results showed that Clone #5 binds to a DDSQDYY motif (SEQ ID NO: 383) in PSCA. Example 2 – Designing ADCs from binders having the ability to bind to a human PSCA polypeptide PSCA antibody F12 clone (Clone #5) was conjugated to MMAE through a valine- citrulline dipeptide linker by lysine-NHS coupling chemistry. The drug:antibody ratio (DAR) was determined to be two based on LS / MS. The ADC, F12-MMAE, exhibited specific cytotoxicity against PSCA overexpressing PC-3 cells, both in vitro and in a PC- Attorney Docket No.48881-0042WO1 / 05676 3-PSCA xenografted mouse model, without obvious toxicity (e.g., no body weight loss) (Figure 7). Example 3 – Designing BiKEs from binders having the ability to bind to a human PSCA polypeptide By combining a PSCA binder with an anti-CD16A VH domain antibody (VH7), BiKE molecules were generated based on the PSCA binder (Figure 8). BiKEs with two arms were designed to bring NK cells and cancer cells into proximity, forming immunosynapses and enlisting NK cell ADCC against tumor cells. Two types of BiKEs were produced based on an IgG1 scaffold to achieve prolonged half-life. One type (designed as 1+2 BiKE) was produced with a monovalent anti-CD16A binder; and the other type was produced with a bivalent anti-CD16A (designed as 2+2 BiKE) to increase NK cell binding and reinforce the immunosynapses. The fine tuning of molecular architecture of BiKEs can minimize tonic activation of NK cells mediated by BiKEs in the absence of tumor cells. These BiKEs exhibited effective binding to the recombinant human PSCA and CD16A proteins, as tested by ELISA (Figure 9). Their capability to activate NK cell ADCC was tested on the Promega ADCC reporter cells (Jurkat T-Luc cells). Results revealed that 2+2 BiKE was more potent than 1+2 BiKE (Figure 9). These results demonstrate that BiKEs can be designed and used to direct the killing of cells expressing human PSCA such as PSCA+cancer cells. Example 4 – Designing CARs from binders having the ability to bind to a human PSCA polypeptide Clones #1-#8 are used to make CARs having configurations as set forth in Figures 29-44. Cells (e.g., T cells) designed to express such CARs are used to kill cells expressing human PSCA such as PSCA+cancer cells. Attorney Docket No.48881-0042WO1 / 05676 Example 5 – Designing BiTEs from binders having the ability to bind to a human PSCA polypeptide Clones #1-#8 are used to make BiTEs having configurations as set forth in Figures 64-71. Such BiTEs are used to direct T cells to kill cells expressing human PSCA such as PSCA+cancer cells. Example 6 – Exemplary PSCA polypeptide sequences This Example depicts an amino acid sequence of an exemplary full length human PSCA polypeptide (SEQ ID NO:129) and an exemplary nucleic acid sequence encoding that full length human PSCA polypeptide (SEQ ID NO:130). An exemplary extracellular domain is underlined and was used to identify Clone #1, Clone #2, and Clone #3. Full length human PSCA: MAGLALQPGTALLCYSCKAQVSNEDCLQVENCTQLGEQCWTARIRAVGLLTVIS KGCSLNCVDDSQDYYVGKKNITCCDTDLCNASGAHALQPAAAILALLPALGLLL WGPGQL (SEQ ID NO:129) Nucleic acid encoding full length human PSCA: ATGGCAGGCTTGGCCCTGCAGCCAGGCACTGCCCTGCTGTGCTACTCCTGCAA AGCCCAGGTGAGCAACGAGGACTGCCTGCAGGTGGAGAACTGCACCCAGCT GGGGGAGCAGTGCTGGACCGCGCGCATCCGCGCAGTTGGCCTCCTGACCGTC ATCAGCAAAGGCTGCAGCTTGAACTGCGTGGATGACTCACAGGACTACTACGT GGGCAAGAAGAACATCACGTGCTGTGACACCGACTTGTGCAACGCCAGCGGG GCCCATGCCCTGCAGCCGGCTGCTGCCATCCTTGCGCTGCTCCCTGCACTCGG CCTGCTGCTCTGGGGACCCGGCCAGCTCTAG (SEQ ID NO:130) Example 7 – Sequences of exemplary binders having the ability to bind to a human PSCA polypeptide This Example depicts the amino acid sequences of Fabs and scFvs having the ability to bind to a human PSCA polypeptide. The CDRs and framework sequences also are delineated. Attorney Docket No.48881-0042WO1 / 05676 Anti-PSCA Clone #1 (also referred to as G7) (Fab) Heavy chain variable domain (without first constant domain and partial hinge): QVQLVESGGGLVKPGGSLRLSCAASGFTFSDYYMSWIRQAPGKGLEWVSYISSS GSTIYYADSVKGRFTISRDNAKNSLYLQMNSLRAEDTAVYYCARPLRWGMDV WGQGTTVTVSS (SEQ ID NO:8) Framework Region 1 of heavy chain variable domain: QVQLVESGGGLVKPGGSLRLSCAASGFTFS (SEQ ID NO:4) CDR1 of heavy chain variable domain: DYYMS (SEQ ID NO:1) Framework Region 2 of heavy chain variable domain: WIRQAPGKGLEWVS (SEQ ID NO:5) CDR2 of heavy chain variable domain: YISSSGSTIYYADSVKG (SEQ ID NO:2) Framework Region 3 of heavy chain variable domain: RFTISRDNAKNSLYLQMNSLRAEDTAVYYCAR (SEQ ID NO:6) CDR3 of heavy chain variable domain: PLRWGMDV (SEQ ID NO:3) Framework Region 4 of heavy ch...

Claims

Attorney Docket No.48881-0042WO1 / 05676 WHAT IS CLAIMED IS:

1. An antibody comprising: (i) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:1 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:2 (or SEQ ID NO:2 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:3 (or SEQ ID NO:3 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:9 (or SEQ ID NO:9 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:10 (or SEQ ID NO:10 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:11 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions); (ii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:17 (or SEQ ID NO:17 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:18 (or SEQ ID NO:18 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:19 (or SEQ ID NO:19 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:25 (or SEQ ID NO:25 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:26 (or SEQ ID NO:26 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:27 (or SEQ ID NO:27 with one, two, or three amino acid additions, deletions, or substitutions); (iii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:33 (or SEQ ID NO:33 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:34 (or SEQ ID NO:34 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:35 (or SEQ ID NO:35 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:41 (or SEQ ID NO:41 with one, two, or three amino acid additions,Attorney Docket No.48881-0042WO1 / 05676 deletions, or substitutions), SEQ ID NO:42 (or SEQ ID NO:42 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:43 (or SEQ ID NO:43 with one, two, or three amino acid additions, deletions, or substitutions); (iv) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:49 (or SEQ ID NO:49 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:50 (or SEQ ID NO:50 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:51 (or SEQ ID NO:51 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:57 (or SEQ ID NO:57 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:58 (or SEQ ID NO:58 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:59 (or SEQ ID NO:59 with one, two, or three amino acid additions, deletions, or substitutions); (v) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:65 (or SEQ ID NO:65 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:66 (or SEQ ID NO:66 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:67 (or SEQ ID NO:67 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:73 (or SEQ ID NO:73 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:74 (or SEQ ID NO:74 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:75 (or SEQ ID NO:75 with one, two, or three amino acid additions, deletions, or substitutions); (vi) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:81 (or SEQ ID NO:81 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:82 (or SEQ ID NO:82 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:83 (or SEQ ID NO:83 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:89 (or SEQ ID NO:89 with one, two, or three amino acid additions,Attorney Docket No.48881-0042WO1 / 05676 deletions, or substitutions), SEQ ID NO:90 (or SEQ ID NO:90 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:91 (or SEQ ID NO:91 with one, two, or three amino acid additions, deletions, or substitutions); (vii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:97 (or SEQ ID NO:97 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:98 (or SEQ ID NO:98 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:99 (or SEQ ID NO:99 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:105 (or SEQ ID NO:105 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:106 (or SEQ ID NO:106 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:107 (or SEQ ID NO:107 with one, two, or three amino acid additions, deletions, or substitutions); or (viii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:113 (or SEQ ID NO:113 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:114 (or SEQ ID NO:114 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:115 (or SEQ ID NO:115 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:121 (or SEQ ID NO:121 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:122 (or SEQ ID NO:122 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:123 (or SEQ ID NO:123 with one, two, or three amino acid additions, deletions, or substitutions).

2. The antibody of claim 1, wherein said antibody comprises the ability to bind to SEQ ID NO:

129.

3. The antibody of any one of claims 1-2, wherein said antibody comprises said heavy chain variable domain or region of said (i) and said light chain variable domain orAttorney Docket No.48881-0042WO1 / 05676 region of said (i), or wherein said antibody comprises said heavy chain variable domain or region of said (ii) and said light chain variable domain or region of said (ii).

4. The antibody of claim 3, wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:8 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:16, or wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:24 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:

32.

5. The antibody of any one of claims 1-2, wherein said antibody comprises said heavy chain variable domain or region of said (iii) and said light chain variable domain or region of said (iii), or wherein said antibody comprises said heavy chain variable domain or region of said (iv) and said light chain variable domain or region of said (iv).

6. The antibody of claim 5, wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:40 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:48, or wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:56 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:

64.

7. The antibody of any one of claims 1-2, wherein said antibody comprises said heavy chain variable domain or region of said (v) and said light chain variable domain orAttorney Docket No.48881-0042WO1 / 05676 region of said (v), or wherein said antibody comprises said heavy chain variable domain or region of said (vi) and said light chain variable domain or region of said (vi).

8. The antibody of claim 3, wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:72 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:80, or wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:88 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:

96.

9. The antibody of any one of claims 1-2, wherein said antibody comprises said heavy chain variable domain or region of said (vii) and said light chain variable domain or region of said (vii), or wherein said antibody comprises said heavy chain variable domain or region of said (viii) and said light chain variable domain or region of said (viii).

10. The antibody of claim 9, wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:104 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:112, or wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:120 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:128.Attorney Docket No.48881-0042WO1 / 05676 11. The antibody of any one of claims 1-10, wherein said antibody is a monoclonal antibody.

12. The antibody of any one of claims 1-11, wherein said antibody is an scFv antibody.

13. An antigen binding fragment comprising: (i) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:1 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:2 (or SEQ ID NO:2 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:3 (or SEQ ID NO:3 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:9 (or SEQ ID NO:9 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:10 (or SEQ ID NO:10 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:11 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions); (ii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:17 (or SEQ ID NO:17 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:18 (or SEQ ID NO:18 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:19 (or SEQ ID NO:19 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:25 (or SEQ ID NO:25 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:26 (or SEQ ID NO:26 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:27 (or SEQ ID NO:27 with one, two, or three amino acid additions, deletions, or substitutions); (iii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:33 (or SEQ ID NO:33 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:34 (or SEQ ID NO:34 with one,Attorney Docket No.48881-0042WO1 / 05676 two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:35 (or SEQ ID NO:35 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:41 (or SEQ ID NO:41 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:42 (or SEQ ID NO:42 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:43 (or SEQ ID NO:43 with one, two, or three amino acid additions, deletions, or substitutions); (iv) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:49 (or SEQ ID NO:49 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:50 (or SEQ ID NO:50 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:51 (or SEQ ID NO:51 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:57 (or SEQ ID NO:57 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:58 (or SEQ ID NO:58 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:59 (or SEQ ID NO:59 with one, two, or three amino acid additions, deletions, or substitutions); (v) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:65 (or SEQ ID NO:65 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:66 (or SEQ ID NO:66 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:67 (or SEQ ID NO:67 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:73 (or SEQ ID NO:73 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:74 (or SEQ ID NO:74 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:75 (or SEQ ID NO:75 with one, two, or three amino acid additions, deletions, or substitutions); (vi) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:81 (or SEQ ID NO:81 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:82 (or SEQ ID NO:82 with one, two,Attorney Docket No.48881-0042WO1 / 05676 or three amino acid additions, deletions, or substitutions), and SEQ ID NO:83 (or SEQ ID NO:83 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:89 (or SEQ ID NO:89 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:90 (or SEQ ID NO:90 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:91 (or SEQ ID NO:91 with one, two, or three amino acid additions, deletions, or substitutions); (vii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:97 (or SEQ ID NO:97 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:98 (or SEQ ID NO:98 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:99 (or SEQ ID NO:99 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:105 (or SEQ ID NO:105 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:106 (or SEQ ID NO:106 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:107 (or SEQ ID NO:107 with one, two, or three amino acid additions, deletions, or substitutions); or (viii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:113 (or SEQ ID NO:113 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:114 (or SEQ ID NO:114 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:115 (or SEQ ID NO:115 with one, two, or three amino acid additions, deletions, or substitutions) and a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:121 (or SEQ ID NO:121 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:122 (or SEQ ID NO:122 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:123 (or SEQ ID NO:123 with one, two, or three amino acid additions, deletions, or substitutions).Attorney Docket No.48881-0042WO1 / 05676 14. The antigen binding fragment of claim 13, wherein said antigen binding fragment comprises the ability to bind to SEQ ID NO:

129.

15. The antigen binding fragment of any one of claims 13-14, wherein said antigen binding fragment comprises said heavy chain variable domain or region of said (i) and said light chain variable domain or region of said (i), or wherein said antigen binding fragment comprises said heavy chain variable domain or region of said (ii) and said light chain variable domain or region of said (ii).

16. The antigen binding fragment of claim 15, wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:8 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:16, or wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:24 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:

32.

17. The antigen binding fragment of any one of claims 13-14, wherein said antigen binding fragment comprises said heavy chain variable domain or region of said (iii) and said light chain variable domain or region of said (iii), or wherein said antigen binding fragment comprises said heavy chain variable domain or region of said (iv) and said light chain variable domain or region of said (iv).

18. The antigen binding fragment of claim 17, wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:40 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:48, or wherein said heavy chain variableAttorney Docket No.48881-0042WO1 / 05676 domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:56 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:

64.

19. The antigen binding fragment of any one of claims 13-14, wherein said antigen binding fragment comprises said heavy chain variable domain or region of said (v) and said light chain variable domain or region of said (v), or wherein said antigen binding fragment comprises said heavy chain variable domain or region of said (vi) and said light chain variable domain or region of said (vi).

20. The antigen binding fragment of claim 19, wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:72 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:80, or wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:88 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:

96.

21. The antigen binding fragment of any one of claims 13-14, wherein said antigen binding fragment comprises said heavy chain variable domain or region of said (vii) and said light chain variable domain or region of said (vii), or wherein said antigen binding fragment comprises said heavy chain variable domain or region of said (viii) and said light chain variable domain or region of said (viii).

22. The antibody of claim 21, wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:104 and said light chain variable domain or regionAttorney Docket No.48881-0042WO1 / 05676 comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:112, or wherein said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:120 and said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:

128.

23. The antigen binding fragment of any one of claims 13-22, wherein said antigen binding fragment is monoclonal.

24. The antigen binding fragment of any one of claims 13-23, wherein said antigen binding fragment is a Fab.

25. An antibody domain comprising: (i) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:1 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:2 (or SEQ ID NO:2 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:3 (or SEQ ID NO:3 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:9 (or SEQ ID NO:9 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:10 (or SEQ ID NO:10 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:11 (or SEQ ID NO:1 with one, two, or three amino acid additions, deletions, or substitutions); (ii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:17 (or SEQ ID NO:17 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:18 (or SEQ ID NO:18 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:19 (or SEQ ID NO:19 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ IDAttorney Docket No.48881-0042WO1 / 05676 NO:25 (or SEQ ID NO:25 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:26 (or SEQ ID NO:26 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:27 (or SEQ ID NO:27 with one, two, or three amino acid additions, deletions, or substitutions); (iii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:33 (or SEQ ID NO:33 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:34 (or SEQ ID NO:34 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:35 (or SEQ ID NO:35 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:41 (or SEQ ID NO:41 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:42 (or SEQ ID NO:42 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:43 (or SEQ ID NO:43 with one, two, or three amino acid additions, deletions, or substitutions); (iv) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:49 (or SEQ ID NO:49 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:50 (or SEQ ID NO:50 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:51 (or SEQ ID NO:51 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:57 (or SEQ ID NO:57 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:58 (or SEQ ID NO:58 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:59 (or SEQ ID NO:59 with one, two, or three amino acid additions, deletions, or substitutions); (v) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:65 (or SEQ ID NO:65 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:66 (or SEQ ID NO:66 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:67 (or SEQ ID NO:67 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ IDAttorney Docket No.48881-0042WO1 / 05676 NO:73 (or SEQ ID NO:73 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:74 (or SEQ ID NO:74 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:75 (or SEQ ID NO:75 with one, two, or three amino acid additions, deletions, or substitutions); (vi) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:81 (or SEQ ID NO:81 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:82 (or SEQ ID NO:82 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:83 (or SEQ ID NO:83 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:89 (or SEQ ID NO:89 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:90 (or SEQ ID NO:90 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:91 (or SEQ ID NO:91 with one, two, or three amino acid additions, deletions, or substitutions); (vii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:97 (or SEQ ID NO:97 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:98 (or SEQ ID NO:98 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:99 (or SEQ ID NO:99 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:105 (or SEQ ID NO:105 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:106 (or SEQ ID NO:106 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:107 (or SEQ ID NO:107 with one, two, or three amino acid additions, deletions, or substitutions); or (viii) a heavy chain variable domain or region comprising the amino acid sequences set forth in SEQ ID NO:113 (or SEQ ID NO:113 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:114 (or SEQ ID NO:114 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:115 (or SEQ ID NO:115 with one, two, or three amino acid additions, deletions, or substitutions) or a light chain variable domain or region comprising the amino acidAttorney Docket No.48881-0042WO1 / 05676 sequences set forth in SEQ ID NO:121 (or SEQ ID NO:121 with one, two, or three amino acid additions, deletions, or substitutions), SEQ ID NO:122 (or SEQ ID NO:122 with one, two, or three amino acid additions, deletions, or substitutions), and SEQ ID NO:123 (or SEQ ID NO:123 with one, two, or three amino acid additions, deletions, or substitutions).

26. The antibody domain of claim 25, wherein said antibody domain comprises the ability to bind to SEQ ID NO:

129.

27. The antibody domain of any one of claims 25-26, wherein said antibody domain comprises said heavy chain variable domain or region of said (i) or said light chain variable domain or region of said (i), or wherein said antibody domain comprises said heavy chain variable domain or region of said (ii) or said light chain variable domain or region of said (ii).

28. The antibody domain of claim 27, wherein if said antibody domain comprises said heavy chain variable domain or region of said (i), then said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:8, wherein if said antibody domain comprises said light chain variable domain or region of said (i), then said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:16, wherein if said antibody domain comprises said heavy chain variable domain or region of said (ii), then said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:24, and wherein if antibody domain comprises said light chain variable domain or region of said (ii), then said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:32.Attorney Docket No.48881-0042WO1 / 05676 29. The antibody domain of any one of claims 25-26, wherein said antibody domain comprises said heavy chain variable domain or region of said (iii) or said light chain variable domain or region of said (iii), or wherein said antibody domain comprises said heavy chain variable domain or region of said (iv) or said light chain variable domain or region of said (iv).

30. The antibody domain of claim 29, wherein if said antibody domain comprises said heavy chain variable domain or region of said (iii), then said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:40, wherein if said antibody domain comprises said light chain variable domain or region of said (iii), then said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:48, wherein if said antibody domain comprises said heavy chain variable domain or region of said (iv), then said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:56, and wherein if antibody domain comprises said light chain variable domain or region of said (iv), then said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:

64.

31. The antibody domain of any one of claims 25-26, wherein said antibody domain comprises said heavy chain variable domain or region of said (v) or said light chain variable domain or region of said (v), or wherein said antibody domain comprises said heavy chain variable domain or region of said (vi) or said light chain variable domain or region of said (vi).

32. The antibody domain of claim 31, wherein if said antibody domain comprises said heavy chain variable domain or region of said (v), then said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:72, wherein if said antibody domainAttorney Docket No.48881-0042WO1 / 05676 comprises said light chain variable domain or region of said (v), then said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:80, wherein if said antibody domain comprises said heavy chain variable domain or region of said (vi), then said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:88, and wherein if antibody domain comprises said light chain variable domain or region of said (vi), then said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:

96.

33. The antibody domain of any one of claims 25-26, wherein said antibody domain comprises said heavy chain variable domain or region of said (vii) or said light chain variable domain or region of said (vii), or wherein said antibody domain comprises said heavy chain variable domain or region of said (viii) or said light chain variable domain or region of said (viii).

34. The antibody domain of claim 33, wherein if said antibody domain comprises said heavy chain variable domain or region of said (vii), then said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:104, wherein if said antibody domain comprises said light chain variable domain or region of said (vii), then said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:112, wherein if said antibody domain comprises said heavy chain variable domain or region of said (viii), then said heavy chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:120, and wherein if antibody domain comprises said light chain variable domain or region of said (viii), then said light chain variable domain or region comprises an amino acid sequence having at least 90 percent identity to the amino acid sequence set forth in SEQ ID NO:128.Attorney Docket No.48881-0042WO1 / 05676 35. The antibody domain of any one of claims 25-34, wherein said antibody domain is monoclonal.

36. The antibody domain of any one of claims 25-35, wherein said antibody domain is a VH domain.

37. A chimeric antigen receptor comprising an antigen binding domain, a hinge, a transmembrane domain, and one or more signaling domains, wherein said antigen binding domain comprises an antibody, an antigen-binding fragment, or an antibody domain of any one of claims 1-36.

38. The chimeric antigen receptor of claim 37, wherein said antigen binding domain comprises an scFv having the ability to bind to a PSCA polypeptide.

39. The chimeric antigen receptor of any one of claims 37-38, wherein said hinge comprises a hinge set forth in Example 15.

40. The chimeric antigen receptor of any one of claims 37-39, wherein said transmembrane domain comprises a transmembrane domain set forth in Example 16.

41. The chimeric antigen receptor of any one of claims 37-40, wherein said chimeric antigen receptor comprises one or more signaling domains set forth in Example 17.

42. A cell comprising a chimeric antigen receptor of any one of claims 37-41.

43. The cell of claim 42, wherein said cell is a T cell, a stem cell, or an NK cell.

44. A cell engager comprising a first antigen binding domain, a linker, and a second antigen binding domain, wherein said first antigen binding domain comprises an antibody, an antigen-binding fragment, or an antibody domain of any one of claims 1-36.Attorney Docket No.48881-0042WO1 / 05676 45. The cell engager of claim 44, wherein said first antigen binding domain comprises a VH having the ability to bind to a PSCA polypeptide.

46. The cell engager of claim 44, wherein said first antigen binding domain is an IgG having the ability to bind to a PSCA polypeptide.

47. The cell engager of any one of claims 44-46, wherein said linker comprises a linker set forth in Example 12 or Example 15.

48. The cell engager of any one of claims 44-47, wherein said second antigen binding domain binds to a polypeptide expressed on the surface of T cells.

49. The cell engager of claim 48, wherein said polypeptide expressed on the surface of T cells is a CD3 polypeptide.

50. The cell engager of claim 48, wherein said second antigen binding domain is an antigen binding domain set forth in Example 19.

51. The cell engager of any one of claims 44-47, wherein said second antigen binding domain binds to a polypeptide expressed on the surface of NK cells.

52. The cell engager of claim 51, wherein said polypeptide expressed on the surface of NK cells is a CD16a, NKG2A, NKG2D, NKp30, NKp44, or NKp46 polypeptide.

53. The cell engager of claim 75, wherein said second antigen binding domain is an antigen binding domain set forth in Example 20.

54. The cell engager of any one of claims 44-53, wherein said cell engager comprises a third antigen binding domain.Attorney Docket No.48881-0042WO1 / 05676 55. The cell engager of claim 54, wherein said third antigen binding domain binds to a polypeptide expressed on the surface of NK cells.

56. The cell engager of claim 55, wherein said polypeptide expressed on the surface of NK cells is a CD16a, NKG2A, NKG2D, NKp30, NKp44, or NKp46 polypeptide.

57. The cell engager of claim 55, wherein said third antigen binding domain is an antigen binding domain set forth in Example 20.

58. A nucleic acid comprising a nucleic acid sequence encoding at least part of said antibody, said antigen-binding fragment, or said antibody domain of any one of claims 1- 36.

59. The nucleic acid of claim 58, wherein said nucleic acid sequence encodes said heavy chain variable domain or region of any one of said (i)-(viii) of claim 1 or said light chain variable domain or region of any one of said (i)-(viii) of claim 1.

60. The nucleic acid of any one of claims 58-59, wherein said nucleic acid is a viral vector.

61. The nucleic acid of any one of claims 58-59, wherein said nucleic acid is a phagemid.

62. A nucleic acid comprising a nucleic acid sequence encoding a chimeric antigen receptor of any one of claims 37-41 or a cell engager of any one of claims 44-57.

63. The nucleic acid of claim 62, wherein said nucleic acid is a viral vector.

64. The nucleic acid of claim 62, wherein said nucleic acid is a phagemid.Attorney Docket No.48881-0042WO1 / 05676 65. A host cell comprising a nucleic acid of any one of claims 62-64.

66. A host cell that expresses a chimeric antigen receptor of any one of claims 37-41 or a cell engager of any one of claims 44-57.

67. The host cell of any one of claims 65-66, wherein said host cell is a T cell, stem cell, or NK cell.

68. An antibody-drug conjugate (ADC) comprising an antigen binging domain covalently linked to a drug, wherein said antigen binging domain comprises an antibody, an antigen binding fragment, or an antibody domain of any one of claims 1-36.

69. The ADC of claim 68, wherein said antigen binding domain comprises an scFv having the ability to bind to a PSCA polypeptide.

70. The ADC of any one of claims 68-69, wherein said drug is selected from the group consisting of auristatins, mertansine, or pyrrolobenzodiazepine (PBD) dimers.

71. A composition comprising an antibody, an antigen binding fragment, or an antibody domain of any one of claims 1-36.

72. The composition of claim 71, wherein said composition comprises said antibody of any one of claims 1-12.

73. The composition of claim 71, wherein said composition comprises said antigen binding fragment of any one of claims 13-24.

74. The composition of claim 71, wherein said composition comprises said antibody domain of any one of claims 25-36.Attorney Docket No.48881-0042WO1 / 05676 75. A composition comprising a cell engager of any one of claims 44-57.

76. A composition comprising a cell of any one of claims 42-43 and 65-67.

77. A composition comprising an ADC of any one of claims 68-70.

78. The composition of any one of claims 71-77, wherein said composition comprises a checkpoint inhibitor.

79. The composition of claim 78, wherein said checkpoint inhibitor is selected from the group consisting of cemiplimab, nivolumab, pembrolizumab, JTX-4014, spartalizumab, camrelizumab, sintilimab, tislelizumab, toripalimab, dostarlimab, INCMGA00012, AMP-224, AMP-514, avelumab, durvalumab, atezolizumab, KN035, CK-301, AUNP12, CA-170, BMS-986189, and ipilimumab.

80. A method of treating a mammal having cancer, wherein said method comprises administering, to said mammal, a composition of any one of claims 71-79.

81. The method of claim 80, wherein said mammal is a human.

82. The method of any one of claims 80-81, wherein said cancer is a PSCA+cancer.

83. The method of claim 82, wherein said PSCA+cancer is selected from the group consisting of PSCA+prostate cancer, PSCA+metastatic prostate cancer, PSCA+bladder cancer, PSCA+renal cell cancer, and PSCA+pancreatic cancer.

84. The method of any one of claims 80-83, wherein the number of cancer cells within said mammal is reduced following said administering step.Attorney Docket No.48881-0042WO1 / 05676 85. A method of treating a mammal having cancer, wherein said method comprises: (a) administering, to said mammal, said composition of any one of claims 71-77, and (b) administering, to said mammal, a composition comprising a checkpoint inhibitor.

86. The method of claim 85, wherein said mammal is a human.

87. The method of any one of claims 85-86, wherein said cancer is a PSCA+cancer.

88. The method of claim 87, wherein said PSCA+cancer is selected from the group consisting of PSCA+prostate cancer, PSCA+metastatic prostate cancer, PSCA+bladder cancer, PSCA+renal cell cancer, and PSCA+pancreatic cancer.

89. The method of any one of claims 85-88, wherein said checkpoint inhibitor is selected from the group consisting of cemiplimab, nivolumab, pembrolizumab, JTX- 4014, spartalizumab, camrelizumab, sintilimab, tislelizumab, toripalimab, dostarlimab, INCMGA00012, AMP-224, AMP-514, avelumab, durvalumab, atezolizumab, KN035, CK-301, AUNP12, CA-170, BMS-986189, and ipilimumab.

90. The method of any one of claims 85-89, wherein the number of cancer cells within said mammal is reduced following said administering steps (a) and (b).

91. A method for binding a binding molecule to a PSCA polypeptide, wherein said method comprises contacting said PSCA polypeptide with an antibody, an antigen binding fragment, or an antibody domain of any one of claims 1-36.

92. The method of claim 91, wherein said contacting is performed in vitro.

93. The method of claim 91, wherein said contacting is performed in vivo.Attorney Docket No.48881-0042WO1 / 05676 94. The method of claim 93, wherein said contacting is performed within a mammal by administering said antibody, said antigen binding fragment, or said antibody domain to said mammal.

95. The method of claim 94, wherein said mammal is a human.

96. A method for binding a binding molecule to a PSCA polypeptide, wherein said method comprises contacting said PSCA polypeptide with a chimeric antigen receptor of any one of claims 37-41, a cell engager of any one of claims 44-57, or an ADC of any one of claims 68-70.

97. The method of claim 96, wherein said contacting is performed in vitro.

98. The method of claim 96, wherein said contacting is performed in vivo.

99. The method of claim 98, wherein said contacting is performed within a mammal by administering said chimeric antigen receptor, said cell engager, or said ADC to said mammal.

100. The method of claim 99, wherein said mammal is a human.