Constructs targeting MSLN ECD and uses thereof

Abstract

The present application provides constructs comprising an antibody moiety that specifically binds to a mesothelin extracellular domain. Also provided are methods of making and using these constructs, and uses thereof, including treating and diagnosing diseases.

Description

CONSTRUCTS TARGETING MSLN ECD AND USES THEREOFCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Application No. 63 / 616,174, filed on December 29, 2023, the contents of which are incorporated herein by reference in its entirety.REFERENCE TO AN ELECTRONIC SEQUENCE LISTING

[0002] The contents of the electronic sequence listing (750042002440SEQLIST.xml; Size: 389,800 bytes; and Date of Creation: December 13, 2024) is herein incorporated by reference in its entirety.FIELD OF THE INVENTION

[0003] This invention pertains to antibody constructs comprising an antibody moiety that specifically binds to mesothelin extracellular domain, and uses thereof, including treating and diagnosing diseases.BACKGROUND OF THE INVENTION

[0004] Mesothelin (MSLN) is a protein that was identified and cloned by screening for the antigen of a cancer differentiation antibody KI (Chang K, Pastan I. 1996; Proc. Natl. Acad. Sci. USA, 93:136-40). MSLN is produced as a GPLanchored 69 kDa precursor protein (pre-pro mesothelin); proteolysis of pre-pro mesothelin produces a GPLanchored 303 amino acid (40 kDa) mesothelin fragment and an amino-terminal 31 kDa fragment released by furin cleavage, called MPF (megakaryocyte potentiating factor; Yamaguchi N., et al., 1994; J. Biol. Chem. 269:805-808). Multiple proteases within the extracellular environment can cleave MSLN at different extracellular sites, releasing soluble mesothelin (shedding; Liu X., et al., 2020;Commun. Biol.; 3:728).

[0005] In adult human tissues, MSLN is normally expressed in the mesothelia of the peritoneal, pleural and pericardial cavities (Chang K., et al., 1992; Am. J. Surg. Pathol.; 16:259-68). MSLN is most highly expressed, for example, in squamous epithelial cells of the tonsil crypts, and incells of the rectal mucosa; MSLN is expressed less so in non- vital adult tissues, such as gallbladder, thymus and fallopian tubes (Weidemann S., et al., 2021; Biomedicines. 9: 397). While expression of MSLN on the cell surface serves as a differentiation marker, the exact role of mesothelin under normal physiological conditions is not known. Mice with a homozygous knockout of MSLN had normal development and reproductive capabilities, suggesting that mesothelin is not an essential gene (Bera T.K., el al., 2000; Mol. Cell. Biol; 20:2902 -2906). Later studies demonstrated that the ultrastructure of the peritoneal mesothelial lining was affected in the AfSZJV'7’ knockout mice, indicating a possible role for mesothelin in cell adhesion and migration (Hilliard T.S. et al., 2021; Ini J Mol Sei. 22:12443).

[0006] Mesothelin over-expression has been identified in many solid tumors, most robustly in mesothelioma (Galloway M.L., et al., 2006; Histopathology 48:767-769), epithelial ovarian cancer (Hassan R., et al., 2006; Clin. Cancer Res. 12:447-53), pancreatic adenocarcinoma (Sharon E., et al., 2012; Clin. Chem. Lab. Med. 50:721-5), and also in lung cancer (Ho M., et al., 2007; Clin, Cancer Res. 1.3: 1571-1575) and uterine malignancies (Dainty L.A., et al., 2007; Gynecol. Oncol. 105:563-570), as well as cholangiocarcinoma (Yu L., et al., 2010; J. Cancer 1:141-149). The low and very limited expression of MSLN in normal tissues and the overexpression in tumors makes MSLN an ideal target for cancer therapy.

[0007] Pancreatic cancer accounts for about 3% of all cancers in the US and about 7% of all cancer deaths. Worldwide, it is estimated that 64,050 people will be diagnosed with pancreatic cancer in 2023; of these, about 50,550 people will die, according to the American Cancer Society, making pancreatic cancer the 12th most common cancer in men and the 11th most common cancer in women. There were more than 495,000 new cases of pancreatic cancer in 2020 (World Cancer Research Fund International).

[0008] Mesothelioma is a rare and aggressive neoplasm arising most commonly on the mesothelial surfaces of tissues in the pleura but can also occur in the peritoneum, pericardium and the tunica vaginalis. Approximately 80% of mesothelioma cases can be attributed to asbestos exposure. In the US each year, about 3,000 people are diagnosed with mesothelioma and 2,500 people die of the disease. Worldwide, it is estimated that as many as 43,000 people die annually from mesothelioma. With increased professional and environmental exposure to asbestos in developing countries, the number of mesothelioma incidence is still increasing.Under current standard first-line chemotherapy, well performing patients have a median overall survival of about 1 year and a median progression free survival of less than 6 months. To date,no second line treatment or targeted or biological treatment have been approved for treating mesothelioma (Mott FE., et al., 2012; Ochsner J. 12:70-79).

[0009] Ovarian cancer is the 8th most common cancer in women worldwide, with more than 313,000 new cases of ovarian cancer in 2020; it ranks fifth in cancer deaths among women in the US, accounting for more deaths than any other cancer of the female reproductive system in the US and worldwide. It is estimated that in the US, 19,710 new cases of ovarian cancer will be diagnosed in 2023, with an estimated 13,270 deaths; the five-year relative survival rate is 50.8% (National Cancer Institute and World Cancer Research Fund International). In a study conducted in 2023 (Weidemann, S., et al., 2023; Appl. Immunohistochem. Mol. Morphol. 31: 77-83), an ovarian cancer heterogeneity tissue microarray (TMA) was constructed and analyzed by immunohistochemistry (IHC). In samples collected from 220 ovarian cancer patients, mesothelin was interpretable in 2342 of the 2460 (95.2%) of the arrayed tumor samples.

[0010] MSLN is highly expressed in more than 90% of pancreatic cancer, ovarian cancer, and mesotheliomas. It is also highly expressed in some non-solid tumor cancers such as AML. Considering its cancer-favored tissue distribution and its protumorigenic functions, monoclonal antibody -based immunotherapies and adoptive T-cell therapy against MSLN are emerging as attractive strategies in treating pancreatic cancer, mesothelioma, and other MSLN-expressing solid tumors.

[0011] There remains an unmet medical need to treat the patients with the above-mentioned cancers. The disclosures of all publications, patents, patent applications and published patent applications referred to herein are hereby incorporated herein by reference in their entirety.BRIEF SUMMARY OF THE INVENTION

[0012] The present application in one aspect provides constructs (such as isolated constructs) comprising an antibody moiety that specifically binds to a mesothelin (MSLN) extracellular domain (ECD) (“anti-MSLN antibody moiety”). In some embodiments, the constructs (“anti- MSLN constructs”) comprise an antibody moiety (referred to herein as an “anti-MSLN antibody moiety”) that specifically binds to an MSLN ECD.

[0013] Thus, in some aspects, there is provided an anti-MSLN construct comprising an antibody moiety that specifically binds to a mesothelin (MSLN) extracellular domain (ECD) (anti-MSLN antibody moiety), wherein the anti-MSLN antibody moiety comprises: (i) a heavychain variable domain (VH) comprising a heavy chain complementarity determining region (HC- CDR) 1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 16, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a light chain variable domain (VL) comprising a light chain complementarity determining region (LC- CDR) 1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 17, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; (ii) a VH comprising an HC-CDR1, an HC- CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 32, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1 , an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 33, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; (iii) a VH comprising an HC-CDR1, an HC- CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 48, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 49, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; (iv) a VH comprising an HC-CDR1, an HC- CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 64, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 65, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; (V) a VH comprising an HC-CDR1, an HC- CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 82, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or allof the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 83, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; (vi) a VH comprising an HC-CDR1, an HC- CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 98, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 99, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; (vii) a VH comprising an HC-CDR1, an HC- CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 114, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 115, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; (viii) a VH comprising an HC- CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 130, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 131, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; (ix) a VH comprising an HC- CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 147, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 148, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2)two amino acid substitutions in the LC-CDR2 of the reference VL; (X) a VH comprising an HC- CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 163, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 164, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; (xi) a VH comprising an HC- CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 177, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 178, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; (xii) a VH comprising an HC- CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 361, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 362, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; or (xiii) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 375, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC-CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 376, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL. In some embodiments according to (or as applied to) any of the embodiments above, the MSLN ECD comprises the amino acid sequence of SEQ ID NO: 2.

[0014] In some embodiments according to (or as applied to) any of the embodiments above, the anti-MSLN antibody moiety comprises: 1) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 5; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 6, an LC- CDR2 comprising the amino acid sequence of GAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 7; 2) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 19, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 20, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 21; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 22, an LC-CDR2 comprising the amino acid sequence of GNN, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 23; 3) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 35, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 36, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 37; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 38, an LC-CDR2 comprising the amino acid sequence of RNN, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 39; 4) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 52, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 53; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 54, an LC-CDR2 comprising the amino acid sequence of STT, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 55; 5) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 69, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 71; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 72, an LC-CDR2 comprising the amino acid sequence of DAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 73; 6) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 85, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 86, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 87; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 88, an LC-CDR2 comprising the amino acid sequence of RNN, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 89; 7) i) a VH comprising an HC-CDR1 comprising the amino acidsequence of SEQ ID NO: 69, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 103; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 104, an LC- CDR2 comprising the amino acid sequence of SAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 105; 8) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 117, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 118, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 119; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 120, an LC- CDR2 comprising the amino acid sequence of HNS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 121; 9) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 134, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 135, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 136; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, an LC- CDR2 comprising the amino acid sequence of GAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 138; 10) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 150, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 151, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 152; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, an LC- CDR2 comprising the amino acid sequence of AAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 154; 11) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 166, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 167; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, an LC- CDR2 comprising the amino acid sequence of AAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 168; 12) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 242, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 102, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 153; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, an LC- CDR2 comprising the amino acid sequence of AAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 244; or 13) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 52, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 364;and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 365, an LC-CDR2 comprising the amino acid sequence of NNN, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 366.

[0015] In some embodiments according to (or as applied to) any of the embodiments above, the anti-MSLN antibody moiety comprises: 1) i) a VH comprising the amino acid sequence of SEQ ID NO: 16, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 16; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 17, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 17; 2) i) a VH comprising the amino acid sequence of SEQ ID NO: 32, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 32; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 33, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 33; 3) i) a VH comprising the amino acid sequence of SEQ ID NO: 48, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 48; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 49, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 49; 4) i) a VH comprising the amino acid sequence of SEQ ID NO: 64, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 64; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 65, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 65; 5) i) a VH comprising the amino acid sequence of SEQ ID NO: 82, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 82; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 83, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 83; 6) i) a VH comprising the amino acid sequence of SEQ ID NO: 98, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 98; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 99, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 99; 7) i) a VH comprising the amino acid sequence of SEQ ID NO: 114, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 114; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 115, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 115; 8) i) a VHcomprising the amino acid sequence of SEQ ID NO: 130, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 130; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 131, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 131; 9) i) a VH comprising the amino acid sequence of SEQ ID NO: 147, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 147; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 148, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 148; 10) i) a VH comprising the amino acid sequence of SEQ ID NO: 163, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 163; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 164, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 164; 11) i) a VH comprising the amino acid sequence of SEQ ID NO: 177, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 177; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 178, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 178; 12) i) a VH comprising the amino acid sequence of SEQ ID NO: 361, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 361; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 362, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 362; or 13) i) a VH comprising the amino acid sequence of SEQ ID NO: 375, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 375; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 376, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 376.

[0016] In some embodiments according to (or as applied to) any of the embodiments above, the anti-MSLN antibody moiety is a full-length antibody, a Fab, a Fab’, a F(ab’)2, an Fv, or a single chain Fv (scFv). In some embodiments according to (or as applied to) any of the embodiments above, the anti-MSLN antibody moiety is an scFv that comprises the amino acid sequence of any one of SEQ ID NOs: 18, 34, 50, 66, 84, 100, 101, 116, 132, 149, 165, 363, and 377.

[0017] In some embodiments according to (or as applied to) any of the embodiments above, the anti-MSLN construct is an anti-MSLN chimeric antigen receptor (CAR) comprising: (a) an extracellular domain comprising the anti-MSLN antibody moiety; (b) a transmembrane domain;and (c) an intracellular signaling domain. In some embodiments according to (or as applied to) any of the embodiments above, (i) the intracellular signaling domain comprises a primary immune cell signaling sequence derived from CD3^, TCR^, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, or CD66d; and / or (ii) the intracellular signaling domain further comprises a costimulatory signaling sequence derived from CD28, CD30, 4-1BB, DAP10, ICOS, or 0X40.

[0018] In some embodiments according to (or as applied to) any of the embodiments above, the anti-MSLN construct is an anti-MSLN chimeric antibody-T cell receptor (TCR) construct (caTCR) comprising: (a) an extracellular domain comprising the anti-MSLN antibody moiety; and (b) a TCR module (TCRM), wherein the TCRM comprises a first TCR domain (TCRD) comprising a first TCR transmembrane domain (TCR-TM) and a second TCRD comprising a second TCR-TM, wherein the TCRM is capable of associating with at least one TCR-associated signaling molecule. In some embodiments according to (or as applied to) any of the embodiments above, (i) the first TCR-TM is derived from one of the transmembrane domains of a naturally occurring TCR and the second TCR-TM is derived from the other transmembrane domain of the naturally occurring TCR; and / or (ii) the at least one TCR-associated signaling molecule is selected from the group consisting of CD35s, CD3ys, and ( . In some embodiments according to (or as applied to) any of the embodiments above, (a) (i) the first TCR-TM is derived from TCRy, and the second TCR-TM is derived from TCR5; or (ii) the second TCR-TM is derived from TCRy, and the first TCR-TM is derived from TCR5; or (b) (i) the first TCR-TM is derived from TCRa, and the second TCR-TM is derived from TCRP; or (ii) the second TCR- TM is derived from TCRa, and the first TCR-TM is derived from TCRp.

[0019] In some embodiments according to (or as applied to) any of the embodiments above, the construct is an anti-MSLN chimeric signaling receptor (CSR) comprising: (a) a target-binding module comprising the anti-MSLN antibody moiety; (b) a transmembrane module; and (c) a costimulatory immune cell signaling module that is capable of providing a co-stimulatory signal to an effector cell; and wherein the CSR lacks a functional primary immune cell signaling domain; optionally wherein the functional primary immune cell signaling domain is derived from a TCR- associated T cell activation molecule selected from the group consisting of CD3^ (TCRQ, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, and CD66d. In some embodiments according to (or as applied to) any of the embodiments above, (i) the transmembrane module of the anti- MSLN CSR comprises one or more transmembrane domains derived from CD28, CD30, CD3s, CD3 , CD45, CD4, CD5, CD8, CD9, CD16, CD22, CD27, CD33, CD37, CD64, CD80, CD86,0X40 (CD134), 4-1BB (CD137), CD154, or ICOS; and / or (ii) the co- stimulatory immune cell signaling module of the anti-MSLN CSR is derived from the intracellular domain of a costimulatory receptor of a TCR, optionally wherein the co-stimulatory receptor is selected from the group consisting of CD28, 4-1BB, 0X40, ICOS, CD27, CD30, CD40, and DAP10.

[0020] In some embodiments according to (or as applied to) any of the embodiments above, the anti-MSLN construct is an anti-MSLN immunoconjugate comprising the anti-MSLN antibody moiety and an effector molecule, wherein the effector molecule is: (i) a therapeutic agent selected from the group consisting of a drug, a toxin, a radioisotope, a protein, a peptide, and a nucleic acid; or (ii) a detectable label.

[0021] In some embodiments according to (or as applied to) any of the embodiments above, the anti-MSLN construct further comprises at least one other antibody moiety that specifically binds to at least one other target which is not MSLN ECD. In some embodiments according to (or as applied to) any of the embodiments above, the at least one other target is: (i) a cell- surface antigen selected from the group consisting of ROR1, ROR2, EpCAM, MUC1, MUC16, FRa, RORA, EGFR, GPRC5D, GPC3, HER2, HER3, DLL3, c-Met, BCMA, CD19, CD22, EGFRvIII, PSMA, and p53; or (ii) a complex comprising an antigenic peptide and a major histocompatibility (MHC) class I protein (an antigenic peptide / MHC class I complex), wherein the antigenic peptide is derived from a protein selected from the group consisting of MSLN, WT1, NDC80, KRAS, AFP, NY-ESO-1, HPV16-E7, PRAME, PSA, and Histone H3.3.

[0022] In some embodiments according to (or as applied to) any of the embodiments above, provided herein is an isolated nucleic acid or a set of isolated nucleic acids encoding the polypeptide component(s) of the anti-MSLN construct of any one of the preceding embodiments.

[0023] In some embodiments according to (or as applied to) any of the embodiments above, provided herein is a host cell comprising the anti-MSLN construct of any one of the preceding embodiments or the nucleic acid(s) of any one of the preceding embodiments.

[0024] In some embodiments according to (or as applied to) any of the embodiments above, provided herein is a method of producing the anti-MSLN construct of any one of the preceding embodiments, comprising culturing the host cell of any one of the preceding embodiments under a condition where the anti-MSLN construct is expressed, and recovering the anti-MSLN construct produced by the host cell.

[0025] In some embodiments according to (or as applied to) any of the embodiments above, provided herein is an effector cell expressing the anti-MSLN construct of any one of the preceding embodiments. In some embodiments according to (or as applied to) any of the preceding embodiments, the effector cell further expresses: (i) a CAR comprising: (a) an extracellular domain that specifically binds to a target; (b) a transmembrane domain; and (c) an intracellular signaling domain; or (ii) a caTCR comprising: (a) an extracellular domain that specifically binds to a target; and (b) a TCRM, wherein the TCRM comprises a first TCRD comprising a first TCR-TM and a second TCRD comprising a second TCR-TM, wherein the TCRM is capable of associating with at least one TCR-associated signaling molecule. In some embodiments according to (or as applied to) any of the embodiments above, (a) (i) the CAR is an anti-MSLN CAR that specifically binds an MSLN ECD target; or (ii) the caTCR is an anti- MSLN caTCR that specifically binds an MSLN ECD target; or (b) the CAR or caTCR specifically binds a target that is not an MSLN ECD. In some embodiments according to (or as applied to) any of the embodiments above, the effector cell further expresses a TCR that specifically binds to a target, and wherein the target is an antigenic peptide / MHC class I complex. In some embodiments according to (or as applied to) any of the embodiments above, the effector cell further expresses a CSR comprising: i) a target-binding domain that specifically binds a target; ii) a transmembrane module; and iii) a co- stimulatory immune cell signaling module that is capable of providing a co- stimulatory signal to the effector cell, wherein the target-binding domain and the co- stimulatory immune cell signaling module are not derived from the same molecule, and wherein the CSR lacks a functional primary immune cell signaling domain; optionally wherein the functional primary immune cell signaling domain is derived from a TCR-associated T cell activation molecule selected from the group consisting of CD3^ (TCRQ, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, and CD66d. In some embodiments according to (or as applied to) any of the embodiments above, (i) the CSR is an anti-MSLN CSR that specifically binds an MSLN ECD target; or (ii) the CSR specifically binds a target that is not an MSLN ECD. In some embodiments according to (or as applied to) any of the embodiments above, the target is: (i) a cell-surface antigen selected from the group consisting of ROR1, ROR2, EpCAM, MUC1, MUC16, FRa, RORA, EGFR, GPRC5D, GPC3, HER2, HER3, DLL3, c-Met, BCMA, CD19, CD22, EGFRvIII, PSMA, and p53; or (ii) an antigenic peptide / MHC class I complex, and wherein the antigenic peptide is derived from a protein selected from the group consisting of MSLN, WT1, NDC80, KRAS, AFP, NY-ESO-1,HPV16-E7, PRAME, PSA, and Histone H3.3. In some embodiments according to (or as applied to) any of the embodiments above, the effector cell is an immune cell, optionally wherein the immune cell is a T cell or a NK cell.

[0026] In some embodiments according to (or as applied to) any of the embodiments above, provided herein is a pharmaceutical composition comprising the anti-MSLN construct of any one of the preceding embodiments, the nucleic acid(s) of any one of the preceding embodiments, the host cell of any one of the preceding embodiments, or the effector cell of any one of the preceding embodiments, and a pharmaceutical acceptable carrier.

[0027] In some embodiments according to (or as applied to) any of the embodiments above, provided herein is a method of detecting MSLN in a sample, comprising contacting the sample with the anti-MSLN construct of any one of the preceding embodiments wherein the effector molecule is a detectable label, and detecting the presence of the label.

[0028] In some embodiments according to (or as applied to) any of the embodiments above, provided herein is a method of treating an individual having a disease or disorder associated with aberrant expression of MSLN, comprising administering to the individual an effective amount of the anti-MSLN construct of any one of the preceding embodiments, the nucleic acid(s) of any one of the preceding embodiments, the host cell of any one of the preceding embodiments, the effector cell of any one of the preceding embodiments, or the pharmaceutical composition of any one of the preceding embodiments.

[0029] In some embodiments according to (or as applied to) any of the embodiments above, provided herein is a method of diagnosing an individual having a disease or disorder associated with aberrant expression of MSLN, comprising: (i) (a) administering an effective amount of the anti-MSLN construct of any one of the preceding embodiments to the individual, wherein the effector molecule is a detectable label; and (b) determining the level of the label in the individual, wherein a level of the label above a threshold level indicates that the individual has the disease or disorder associated with aberrant expression of MSLN; or (ii) (a) contacting a sample derived from the individual with the anti-MSLN construct of any one of the preceding embodiments, wherein the effector molecule is a detectable label; and (b) determining the number of cells bound with the anti-MSLN construct in the sample, wherein a value for the number of cells bound with the anti-MSLN construct above a threshold level indicates that the individual has the disease or disorder associated with aberrant expression of MSLN. In someembodiments according to (or as applied to) any of the embodiments above, the disease or disorder associated with aberrant expression of MSLN is cancer.

[0030] In some embodiments according to (or as applied to) any of the embodiments above, provided herein is a method of killing a target cell that expresses MSLN, the method comprising contacting the target cell with an effective amount of the anti-MSLN construct of any one of the preceding embodiments, the nucleic acid(s) of any one of the preceding embodiments, the host cell of any one of the preceding embodiments, the effector cell of any one of the preceding embodiments, or the pharmaceutical composition of any one of the preceding embodiments.

[0031] Also provided are methods of making any of the anti-MSLN constructs described herein, articles of manufacture, and kits that are suitable for the methods described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various aspects of the disclosure are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present disclosure will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the disclosure are utilized, and the accompanying drawings of which:

[0033] FIG. 1 shows the screening steps taken to isolate high affinity antibody agents capable of binding to mesothelin (MSLN) extracellular domain (ECD) (referred to as “anti-MSLN antibodies” or “anti-MSLN clones”).

[0034] FIG. 2 shows exemplary phage panning results of anti-MSLN phage clones screened by ELISA for binding to MSLN ECD. A control protein (NP) served as a negative control.

[0035] FIG. 3A shows the results of flow cytometry experiments that were performed to screen exemplary anti-MSLN phage clones for binding to MSLN ECD on the surface of Pane- 1 cells engineered to express MSLN. Parental Panc-1 cells (MSLN") served as a negative control.

[0036] FIG. 3B shows the results of flow cytometry experiments that were performed to screen exemplary anti-MSLN phage clones for binding to MSLN on the surface of Pane- 1 cells engineered to express MSLN. Parental Panc-1 cells (MSLN") served as a negative control.

[0037] FIG. 4 shows the results of flow cytometry experiments used to test the binding of anti- MSLN phage clones converted to His-tagged scEv format to OvCAR3 cells, an MSLN+cell line. Binding was detected with an anti-His-APC antibody. Anti-His-APC antibody alone was used as a control. Boxed plots represent the positive control, redundant clones, or clones that were selected for the competition assay.

[0038] FIG. 5A shows the results of a competition assay performed to measure the binding of anti-MSLN scFv Clones A05, A09, and A10 to OvCAR3 cells, an MSLN+cell line, with varying amounts of soluble MSLN present and using a constant amount of anti-MSLN scFv clone. Binding was measured by flow cytometry.

[0039] FIG. 5B shows the results of a competition assay performed to measure the binding of anti-MSLN scFv Clone A13 and positive control antibody to OvCAR3 cells, an MSLN+cell line, with varying amounts of soluble MSLN present and using a constant amount of anti-MSLN scFv clone. Binding was measured by flow cytometry.

[0040] FIG. 5C shows the results of a competition assay performed to measure the binding of anti-MSLN scFv Clones A14, A15, and A16 to OvCAR3 cells, an MSLN+cell line, with varying amounts of soluble MSLN present and using a constant amount of anti-MSLN scFv clone. Binding was measured by flow cytometry.

[0041] FIG. 5D shows the results of a competition assay performed to measure the binding of anti-MSLN scFv Clones A 17 and A24 to OvCAR3 cells, an MSLN+cell line, with varying amounts of soluble MSLN present and using a constant amount of anti-MSLN scFv clone. Binding was measured by flow cytometry.

[0042] FIG. 5E shows the results of a competition assay performed to measure the binding of anti-MSLN scFv Clones A39, A44, and A45 to OvCAR3 cells, an MSLN+cell line, with varying amounts of soluble MSLN present and using a constant amount of anti-MSLN scFv clone. Binding was measured by flow cytometry.

[0043] FIG. 5F shows the results of a competition assay performed to measure the binding of anti-MSLN scFv Clone A46 and negative control antibody to OvCAR3 cells, an MSLN+cell line, with varying amounts of soluble MSLN present and using a constant amount of anti-MSLN scFv clone. Binding was measured by flow cytometry.

[0044] FIG. 6A shows the results of flow cytometry experiments used to test the binding of anti-MSLN scFv Clones A05, A09, and A10 to MSLN+(Pancl-M, BxPC3, HepG2-M, CF- PAC1, CaPan2, AsPCl) and MSLN" (Panc-1, HepG2, 293F) cell lines.

[0045] FIG. 6B shows the results of flow cytometry experiments used to test the binding of anti-MSLN scFv Clones A13 and A14 to MSLN+(Pancl-M, BxPC3, HepG2-M, CF-PAC1, CaPan2, AsPCl) and MSLN" (Panc-1, HepG2, 293F) cell lines.

[0046] FIG. 6C shows the results of flow cytometry experiments used to test the binding of anti-MSLN scFv Clones A15, A16 and A17 to MSLN+(Pancl-M, BxPC3, HepG2-M, CF- PAC1, CaPan2, AsPCl) and MSLN' (Panc-1, HepG2, 293F) cell lines.

[0047] FIG. 6D shows the results of flow cytometry experiments used to test the binding of anti-MSLN scFv Clone A24 and positive control antibody to MSLN+(Pancl-M, BxPC3, HepG2-M, CF-PAC1, CaPan2, AsPCl) and MSLN' (Panc-1, HepG2, 293F) cell lines.

[0048] FIG. 6E shows the results of flow cytometry experiments used to test the binding of anti-MSLN scFv Clones A39, A44 and A45 to MSLN+(Pancl-M, BxPC3, HepG2-M, CF- PAC1, CaPan2, AsPCl) and MSLN" (Panc-1, HepG2, 293F) cell lines.

[0049] FIG. 6F shows the results of flow cytometry experiments used to test the binding of anti-MSLN scFv Clone A46 and negative control antibody to MSLN+(Pancl-M, BxPC3, HepG2-M, CF-PAC1, CaPan2, AsPCl) and MSLN' (Panc-1, HepG2, 293F) cell lines.

[0050] FIG. 7A shows the results of Bio-Layer Interferometry (BLI) experiments performed to measure the binding kinetics of anti-MSLN scFv Clones A05, A09, A10, A13, A14, and A15 to MSLN. Biotinylated MSLN peptide fragments were immobilized on streptavidin coated sensors, and anti-MSLN scFv clones were in solution to measure association and dissociation.

[0051] FIG. 7B shows the results of Bio-Layer Interferometry (BLI) experiments performed to measure the binding kinetics of anti-MSLN scFv Clones A16, A17, A24, A39, A44, A45, and A46 to MSLN. Biotinylated MSLN peptide fragments were immobilized on streptavidin coated sensors, and anti-MSLN scFv clones were in solution to measure association and dissociation.

[0052] FIG. 8A shows the results of an interferon-gamma (IFN-y) release assay to assess the amount of IFN-y released from effector T cells from donor R200 transduced with select anti- MSLN clones in scFv format, upon engagement with target cancer cells Hap 1 -KO (cells with a knockout of the MSLN locus) and Hapl engineered to express MSLN (Hapl-MSLN). A positive control scFv (MSLN +) and mock transduced T cells were used as controls.

[0053] FIG. 8B shows the results of an interferon-gamma (IFN-y) release assay to assess the amount of IFN-y released from effector T cells from donor R256 transduced with select anti- MSLN clones in scFv format, upon engagement with target cancer cells Hapl -KO (cells with a knockout of the MSLN locus) and Hapl engineered to express MSLN (Hapl-MSLN). A positive control scFv (MSLN +) and mock transduced T cells were used as controls.

[0054] FIG. 9A shows the results of a long-term killing assay that was performed to measure the killing efficacy of effector T cells from donor R254 transduced with select anti-MSLNclones in scFv format on OvCAR3 and AsPCl target cells. Both target cell lines are MSLN+, and express luciferase (Luc). Effector cells were mixed with target cells at an effector to target ratio (E:T ratio) of 1:1, and the number of remaining target cells and total T cells were quantified by bioluminescent imaging after 7 days. A positive control scFv (MSLN +) and mock transduced T cells were used as controls.

[0055] FIG. 9B shows the results of a long-term killing assay that was performed to measure the killing efficacy of effector T cells from donor R256 transduced with select anti-MSLN clones in scFv format on OvCAR3 and AsPCl target cells. Both target cell lines are MSLN+, and express luciferase (Luc). Effector cells were mixed with target cells at an effector to target ratio (E:T ratio) of 1:1, and the number of remaining target cells and total T cells were quantified by bioluminescent imaging after 7 days. A positive control scFv (MSLN +) and mock transduced T cells were used as controls.

[0056] FIG. 10A shows the results of a long-term killing assay that was performed to measure the killing efficacy of effector T cells from donor R254 transduced with select anti-MSLN clones in scFv format on OvCAR3 and AsPCl target cells. Both target cell lines are MSLN+, and express luciferase (Luc). Effector cells were mixed with target cells at an effector to target ratio (E:T ratio) of 1:4, and the number of remaining target cells and total T cells were quantified by bioluminescent imaging after 7 days. A positive control scFv (MSLN +) and mock transduced T cells were used as controls.

[0057] FIG. 10B shows the results of a long-term killing assay that was performed to measure the killing efficacy of effector T cells from donor R256 transduced with select anti-MSLN clones in scFv format on OvCAR3 and AsPCl target cells. Both target cell lines are MSLN+, and express luciferase (Luc). Effector cells were mixed with target cells at an effector to target ratio (E:T ratio) of 1:4, and the number of remaining target cells and total T cells were quantified by bioluminescent imaging after 7 days. A positive control scFv (MSLN +) and mock transduced T cells were used as controls.

[0058] FIG. 11A shows the results of a long-term killing assay that was performed to measure the killing efficacy of effector T cells from donor R254 transduced with select anti-MSLN clones in scFv format on OvCAR3 and AsPCl target cells. Both target cell lines are MSLN+, and express luciferase (Luc). Effector cells were mixed with target cells at an effector to target ratio (E:T ratio) of 1:8, and the number of remaining target cells and total T cells were quantifiedby bioluminescent imaging after 7 days. A positive control scFv (MSLN +) and mock transduced T cells were used as controls.

[0059] FIG. 11B shows the results of a long-term killing assay that was performed to measure the killing efficacy of effector T cells from donor R256 transduced with select anti-MSLN clones in scFv format on OvCAR3 and AsPCl target cells. Both target cell lines are MSLN+, and express luciferase (Luc). Effector cells were mixed with target cells at an effector to target ratio (E:T ratio) of 1:8, and the number of remaining target cells and total T cells were quantified by bioluminescent imaging after 10 days. A positive control scFv (MSLN +) and mock transduced T cells were used as controls.

[0060] FIG. 12A shows the results of a flow cytometry experiment that was performed to demonstrate MSLN expression levels in three MSLN+pancreatic adenocarcinoma cell lines, BxPC3 (low MSLN expression), CaPan2 (moderate MSLN expression), and AsPCl (high MSLN expression).

[0061] FIG. 12B shows the results of a lactate dehydrogenase (LDH) release assay that was performed to measure the specific killing of target cell lines BxPC3, CaPan2 and AsPCl using effector T cells from two donors, R82 and R305, transduced with select anti-MSLN clones in caTCR format. Mock transduced effector cells served as controls.

[0062] FIG. 12C shows the results of an interferon-gamma (IFN-y) release assay to assess the amount of IFN-y released from effector T cells from two donors, R82 and R305 transduced with select anti-MSLN clones in caTCR format, when co-cultured with target cell lines BxPC3, CaPan2 and AsPCl. Mock transduced effector cells served as controls.

[0063] FIG. 13A shows the results of a long-term killing assay performed to measure the killing of AsPCl target cells by effector T cells from donor R259 transduced with select anti- MSLN clones in caTCR format + select anti-MSLN clones in CSR format. Target cell viability was measured using crystal violet staining on day 7 following the first E:T cell co-culture, and again on day 4 following a further infusion of target cells. An anti-MSLN CSR derived from a positive control anti-MSLN scFv clone (CSR (C)) was used as a control.

[0064] FIG. 13B shows the results of a long-term killing assay performed to measure the killing of AsPCl target cells by effector T cells from donor R305 transduced with select anti- MSLN clones in caTCR format + select anti-MSLN clones in CSR format. Target cell viability was measured using crystal violet staining on day 7 following the first E:T cell co-culture, andagain on day 4 following a further infusion of target cells. An anti-MSLN CSR derived from a positive control anti-MSLN scFv clone (CSR (C)) was used as a control.

[0065] FIG. 13C shows the results of a long-term killing assay performed to measure the killing of BxPC3 target cells by effector T cells from donor R259 transduced with select anti- MSLN clones in caTCR format + select anti-MSLN clones in CSR format. Target cell viability was measured using crystal violet staining on day 7 following the first E:T cell co-culture, and again on day 4 following a further infusion of target cells. An anti-MSLN CSR derived from a positive control anti-MSLN scFv clone (CSR (C)) was used as a control.

[0066] FIG. 13D shows the results of a long-term killing assay performed to measure the killing of BxPC3 target cells by effector T cells from donor R305 transduced with select anti- MSLN clones in caTCR format + select anti-MSLN clones in CSR format. Target cell viability was measured using crystal violet staining on day 7 following the first E:T cell co-culture, and again on day 4 following a further infusion of target cells. A CSR derived from a positive control anti-MSLN scFv clone (CSR (C)) was used as a control.

[0067] FIG. 14A shows the results of a long-term killing assay performed to measure the killing of AsPCl target cells by effector T cells from donor R259 transduced with select anti- MSLN clones in caTCR format + select anti-MSLN clones in CSR format. Samples were quantified for remaining effector CD3+T cells on day 7 following the first E:T cell co-culture, and again on day 4 following a further infusion of target cells. A CSR derived from a positive control anti-MSLN scFv clone (CSR (C)) was used as a control.

[0068] FIG. 14B shows the results of a long-term killing assay performed to measure the killing of AsPCl target cells by effector T cells from donor R305 transduced with select anti- MSLN clones in caTCR format + select anti-MSLN clones in CSR format. Samples were quantified for remaining effector CD3+T cells on day 7 following the first E:T cell co-culture, and again on day 4 following a further infusion of target cells. A CSR derived from a positive control anti-MSLN scFv clone (CSR (C)) was used as a control.

[0069] FIG. 14C shows the results of a long-term killing assay performed to measure the killing of BxPC3 target cells by effector T cells from donor R259 transduced with select anti- MSLN clones in caTCR format + select anti-MSLN clones in CSR format. Samples were quantified for remaining effector CD3+T cells on day 7 following the first E:T cell co-culture, and again on day 4 following a further infusion of target cells. A CSR derived from a positive control anti-MSLN scFv clone (CSR (C)) was used as a control.

[0070] FIG. 14D shows the results of a long-term killing assay performed to measure the killing of BxPC3 target cells by effector T cells from donor R305 transduced with select anti- MSLN clones in caTCR format + select anti-MSLN clones in CSR format. Samples were quantified for remaining effector CD3+T cells on day 7 following the first E:T cell co-culture, and again on day 4 following a further infusion of target cells. A CSR derived from a positive control anti-MSLN scFv clone (CSR (C)) was used as a control.

[0071] FIG. 15A presents a schematic of an in vivo tumor regression study. Mice were implanted with ST V-cxprcssing tumor cells and 15 days later were treated with T cells that express anti-MSLN Clone A CAR + CSR constructs. Tumor volumes were measured every 2-3 days until the study’s end.

[0072] FIG. 15B shows the mean tumor volume of each group of treated mice. At day 21, mice treated with all anti-MSLN Clone A CAR + CSR-expressing T cells showed evidence of tumor regression, while the tumors of the Mock-treated group of mice continued to grow.DETAILED DESCRIPTION

[0073] It is to be appreciated that certain aspects, modes, embodiments, variations and features of the present methods are described below in various levels of detail in order to provide a substantial understanding of the present technology. It is to be understood that the present disclosure is not limited to particular uses, methods, reagents, compounds, compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0074] The present application provides constructs (referred to herein as “anti-MSLN constructs”) that comprise an antibody moiety (referred to herein as an “anti-MSLN antibody moiety”) that specifically binds to a mesothelin (MSLN) extracellular domain (ECD) (referred to herein as an “MSLN ECD”).

[0075] Using phage display technology, multiple monoclonal antigen-binding antibody fragments that are specific and exhibit high affinity to an MSLN ECD were generated. Flow cytometry assays demonstrated that the antibodies specifically recognized MSLN+cells (e.g., cells expressing MSLN). The data presented herein demonstrate that antibodies against MSLN ECD can be effective therapeutic agents for a cancer (such as, e.g., pancreatic cancer, ovarian cancer, breast cancer, or mesothelioma) characterized by aberrant expression of a target protein.For example, the data presented herein surprisingly shows that T cells co-expressing anti-MSLN ECD CAR + CSR combination constructs were able to significantly reduce tumor volume in an in vivo mouse model.

[0076] The anti-MSLN constructs allow for specific targeting of cells expressing MSLN, such as disease cells expressing (or overexpressing) MSLN. When present in a chimeric antigen receptor (CAR) or chimeric antibody-T cell receptor construct (caTCR) expressed by a T cell, the anti-MSLN antibody moiety specifically redirects human T cells to kill target cells (e.g., cancer cells) expressing MSLN. Furthermore, when fused to a detectable label, the anti-MSLN antibody moiety may be used to visualize changes in the number and localization of MSLN- expressing cells. Such information can, in turn, be used to diagnose and / or prognose target- associated diseases or disorders.

[0077] The present application provides constructs comprising an antibody moiety that specifically binds to an MSLN. Exemplary constructs include, but are not limited to, e. g-, full- length anti-MSLN antibodies, multispecific anti-MSLN constructs (such as a bispecific anti- MSLN antibodies), anti-MSLN CARs, anti-MSLN caTCRs, anti-MSLN chimeric signaling receptors (CSRs), anti-MSLN immunoconjugates, as well as other constructs, as described in further detail below. Each of the anti-MSLN constructs described herein demonstrates high specificity for MSLN ECD.

[0078] The present application also provides nucleic acids that encode the anti-MSLN constructs described herein (or the polypeptide portion(s) thereof).

[0079] Also provided herein are compositions (such as pharmaceutical compositions or formulations) comprising an anti-MSLN construct described herein, or an effector cell expressing or associated with an anti-MSLN construct described herein (such as a T cell expressing an anti-MSLN CAR, an anti-MSLN caTCR, or an anti-MSLN CSR).

[0080] The present application also provides methods of making and using the anti-MSLN constructs (or effector cells expressing or associated with the anti-MSLN constructs) for treatment, for diagnostic purposes, for prognostic purposes, and for inclusion into kits and articles of manufacture useful for the treatment, diagnosis, and / or prognosis of MSLN-associated diseases and disorders.

[0081] Disclosed herein is the development of anti-MSLN constructs (such as full length anti- MSLN antibodies), multispecific anti-MSLN constructs (such as a bispecific anti-MSLN antibodies) that specifically bind mesothelin-positive cells. Also disclosed herein is thedevelopment of anti-MSLN CARs, anti-MSLN caTCRs, and anti-MSLN chimeric signaling receptors that demonstrate enhanced cytotoxic properties. Also disclosed herein is the development of effector cells that demonstrate specific killing of target cells when they comprise, express, or are associated with the anti-MSLN CARs, anti-MSLN caTCRs, and anti- MSLN CSRs of the present disclosure.Definitions

[0082] Before describing the disclosed embodiments in detail, it is to be understood that the present disclosure is not limited to particular compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0083] Unless defined otherwise, all technical and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art to which this technology belongs. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to “a molecule” optionally includes a combination of two or more such molecules, and the like.

[0084] As used herein, the term “about” in reference to a number is generally taken to include numbers that fall within a range of 1%, 5%, or 10% in either direction (greater than or less than) of the number unless otherwise stated or otherwise evident from the context (except where such number would be less than 0% or exceed 100% of a possible value).

[0085] As used herein, the “administration” of an agent or drug to a subject gene name includes any route of introducing or delivering to a subject a compound to perform its intended function. Administration can be carried out by any suitable route, including but not limited to, orally, intranasally, parenterally (intravenously, intramuscularly, intraperitoneally, or subcutaneously), rectally, intrathecally, intratumorally or topically. Administration includes self-administration and the administration by another.

[0086] The terms “cancer” or “tumor” are used interchangeably and refer to the presence of cells possessing characteristics typical of cancer-causing cells, such as uncontrolled proliferation, immortality, metastatic potential, rapid growth and proliferation rate, and certain characteristic morphological features. Cancer cells are often in the form of a tumor, but suchcells can exist alone within an animal, or can be a non-tumorigenic cancer cell. As used herein, the term “cancer” includes premalignant as well as malignant cancers.

[0087] As used herein “mesothelin” or “MSLN” refers to any naturally occurring MSLN from any vertebrate source, including mammals such as primates (e.g., humans, non-human primates (e.g., cynomolgus or rhesus monkeys)) and rodents (e.g., mice and rats), unless otherwise indicated. The term also encompasses naturally occurring variants of MSLN, e.g., allelic variants, and isoforms. The term “mesothelin extracellular domain,” “MSLN extracellular domain,” or “MSLN ECD” refers to any naturally occurring MSLN ECD from any vertebrate source, including mammals such as primates (e.g., humans, non-human primates (e.g., cynomolgus or rhesus monkeys)) and rodents (e.g., mice and rats), unless otherwise indicated. A MSLN ECD may comprise the amino acid sequence of SEQ ID NO: 2 (e.g., amino acids 296- 580 of human MSLN). The term “anti-MSLN antibody moiety” as used herein specifically refers to an antibody moiety that specifically binds to an MSLN ECD. The anti-MSLN antibody moieties may bind different regions of MSLN ECD or may bind the same region of an MSLN ECD but binds a non-overlapping epitope.

[0088] As used herein, “treatment” or “treating” is an approach for obtaining beneficial or desired results, including clinical results. For purposes of the present application, beneficial or desired clinical results include, but are not limited to, one or more of the following: alleviating one or more symptoms resulting from the disease, diminishing the extent of the disease, stabilizing the disease (e.g., preventing or delaying the worsening of the disease), preventing or delaying the spread (e.g., metastasis) of the disease, preventing or delaying the recurrence of the disease, delay or slowing the progression of the disease, ameliorating the disease state, providing a remission (partial or total) of the disease, decreasing the dose of one or more other medications required to treat the disease, delaying the progression of the disease, increasing or improving the quality of life, increasing weight gain, and / or prolonging survival. Also encompassed by “treatment” is a reduction of pathological consequence of cancer (such as, for example, tumor volume). The methods provided herein contemplate any one or more of these aspects of treatment.

[0089] ‘ ‘Activation,” as used herein in relation to T cells, refers to the state of a T cell that has been sufficiently stimulated to induce detectable cellular proliferation. Activation can also be associated with induced cytokine production, and detectable effector functions.

[0090] The term “antibody moiety” includes full-length antibodies and antigen-binding fragments thereof. A full-length antibody comprises two heavy chains and two light chains. The variable regions of the light and heavy chains are responsible for antigen binding. The variable regions in each chain generally comprise three highly variable loops called the complementarity determining regions (CDRs) (light chain (LC) CDRs including LC-CDR1, LC-CDR2, and LC- CDR3, heavy chain (HC) CDRs including HC-CDR1, HC-CDR2, and HC-CDR3). CDR boundaries for the antibodies and antigen-binding fragments disclosed herein may be defined or identified by the conventions of Kabat, Chothia, or Al-Lazikani (Al-Lazikani 1997; Chothia 1985; Chothia 1987; Chothia 1989; Kabat 1987; Kabat 1991). The three CDRs of the heavy or light chains are interposed between flanking stretches known as framework regions (FRs), which are more highly conserved than the CDRs and form a scaffold to support the hypervariable loops. The constant regions of the heavy and light chains are not involved in antigen binding but exhibit various effector functions. Antibodies are assigned to classes based on the amino acid sequence of the constant region of their heavy chain. The five major classes or isotypes of antibodies are IgA, IgD, IgE, IgG, and IgM, which are characterized by the presence of a, 5, a, y, and p heavy chains, respectively. Several of the major antibody classes are divided into subclasses such as IgGl (yl heavy chain), IgG2 (y2 heavy chain), IgG3 (y3 heavy chain), IgG4 (y4 heavy chain), IgAl (al heavy chain), or IgA2 (a2 heavy chain).

[0091] The term “antigen-binding fragment” as used herein refers to an antibody fragment including, but not limited to, e.g., a diabody, a Fab, a Fab', a F(ab')2, an Fv fragment, a disulfide stabilized Fv fragment (dsFv), a (dsFv , a bispecific dsFv (dsFv-dsFv'), a disulfide stabilized diabody (ds diabody), a single-chain antibody molecule (scFv), an scFv dimer (bivalent diabody), a multispecific antibody formed from a portion of an antibody comprising one or more CDRs, a camelized single domain antibody, a nanobody, a domain antibody, a bivalent domain antibody, or any other antibody fragment that binds to an antigen but does not comprise a complete antibody structure. An antigen-binding fragment is capable of binding to the same antigen to which the parent antibody or a parent antibody fragment e.g., a parent scFv) binds. In some embodiments, an antigen-binding fragment may comprise one or more CDRs from a particular human antibody grafted to a framework region from one or more different human antibodies.

[0092] The term “epitope” as used herein refers to the specific group of atoms or amino acids on an antigen to which an antibody or antibody moiety binds. Two antibodies or antibodymoieties may bind the same epitope (or overlapping epitopes) within an antigen if they exhibit competitive binding for the antigen.

[0093] As used herein, a first antibody moiety “competes” for binding to MSLN with a second antibody moiety when the first antibody moiety inhibits binding of the second antibody moiety to MSLN by at least about 50% (such as at least about any of 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98% or 99%) in the presence of an equimolar concentration of the first antibody moiety, or vice versa. A high throughput process for “binning” antibodies based upon their cross-competition is described in PCT Publication No. WO 03 / 48731.

[0094] As use herein, the term “specifically binds,” “specifically recognizes” or “is specific for” refers to measurable and reproducible interactions (such as binding between a target and an antibody or an antibody moiety) that are determinative of the presence of the target in the presence of a heterogeneous population of molecules, including biological molecules. For example, an antibody or antibody moiety that specifically binds to a target (which can be an epitope) is an antibody or antibody moiety that binds the target with greater affinity, avidity, more readily, and / or with greater duration than it binds to other targets. In some embodiments, an antibody or antibody moiety that specifically binds to an antigen reacts with one or more antigenic determinants of the antigen (for example an epitope on the extracellular domain of MSLN) with a binding affinity that is at least about 10 times its binding affinity for other targets.

[0095] An “isolated” anti-MSLN construct as used herein refers to an anti-MSLN construct that (1) is not associated with proteins found in nature, (2) is free of other proteins from the same source, (3) is expressed by a cell from a different species, or (4) does not occur in nature.

[0096] The term “isolated nucleic acid” as used herein is intended to mean a nucleic acid of genomic, cDNA, or synthetic origin or some combination thereof, which by virtue of its origin the “isolated nucleic acid” (1) is not associated with all or a portion of a polynucleotide in which the “isolated nucleic acid” is found in nature, (2) is operably linked to a polynucleotide which it is not linked to in nature, or (3) does not occur in nature as part of a larger sequence.

[0097] As used herein, the term “CDR” or “complementarity determining region” is intended to mean the non-contiguous antigen combining sites found within the variable region of both heavy and light chain polypeptides. These particular regions have been described by Kabat et al., J. Biol. Chem. 252:6609-6616 (1977); Kabat et al., U.S. Dept, of Health and Human Services, “Sequences of proteins of immunological interest” (1991); by Chothia et al., J. Mol. Biol. 196:901-917 (1987); and MacCallum et al., J. Mol. Biol. 262:732-745 (1996), where thedefinitions include overlapping or subsets of amino acid residues when compared against each other. Nevertheless, application of either definition to refer to a CDR of an antibody or grafted antibodies or variants thereof is intended to be within the scope of the term as defined and used herein. The amino acid residues which encompass the CDRs as defined by each of the above cited references are set forth below in Table 7 as a comparison.Table 1. CDR Definitions' Residue numbering follows the nomenclature of Kabat et al., J. Biol. Chem. 252:6609-6616 (1977); Kabat et al., U.S. Dept, of Health and Human Services, “Sequences of proteins of immunological interest” (1991).2Residue numbering follows the nomenclature of Chothia et al., J. Mol. Biol. 196:901-917 (1987); Al-Lazikani B. et al., J. Mol. Biol., ITS 927-948 (1997).3Residue numbering follows the nomenclature of MacCallum et al., J. Mol. Biol. 262:732-745 (1996); Abhinandan and Martin, Mol. Immunol., 45: 3832-3839 (2008).4Residue numbering follows the nomenclature of Lefranc M.P. et al., Dev. Comp. Immunol., 27: 55-77 (2003); and Honegger and Pliickthun, J. Mol. Biol., 309:657-670 (2001).5Residue numbering follows the nomenclature of Honegger and Pliickthun, J. Mol. Biol., 309:657-670 (2001).

[0098] The term “chimeric antibodies” refer to antibodies in which a portion of the heavy and / or light chain is identical or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit a biological activity of interest (e.g.,binding to MSLN) (see U.S. Patent No. 4,816,567; and Morrison et al., Proc. Natl. Acad. Sci. USA, 81:6851-6855 (1984)).

[0099] The term “semi-synthetic” in reference to an antibody or antibody moiety means that the antibody or antibody moiety has one or more naturally occurring sequences and one or more non-naturally occurring (i.e., synthetic) sequences or amino acids.

[0100] ‘ ‘Fv” is the minimum antibody fragment which contains a complete antigen-recognition and antigen-binding site. This fragment consists of a dimer of one heavy- and one light- chain variable region domain in tight, non-covalent association. From the folding of these two domains emanate six hypervariable loops (3 loops each from the heavy and light chain) that contribute the amino acid residues for antigen binding and confer antigen binding specificity to the antibody. However, even a single variable domain (or half of an Fv comprising only three CDRs specific for an antigen) has the ability to recognize and bind antigen, although at a lower affinity than the entire binding site.

[0101] “Single-chain Fv,” also abbreviated as “sFv” or “scFv,” are antibody fragments that comprise the VH and VL connected into a single polypeptide chain. In some embodiments, the scFv polypeptide further comprises a polypeptide linker between the VH and VL which permits the scFv to form the desired structure for antigen binding. For a review of scFv, see Pluckthiin in The Pharmacology of Monoclonal Antibodies, vol. 113, Rosenburg and Moore eds., Springer- Verlag, New York, pp. 269-315 (1994).

[0102] The term “diabodies” refers to small antibody fragments prepared by constructing scFv fragments (see preceding paragraph) typically with short linkers (such as about 5 to about 10 residues) between the VH and VL such that inter-chain but not intra-chain pairing of the variable domains is achieved, resulting in a bivalent fragment, i.e., fragment having two antigen-binding sites. Bispecific diabodies are heterodimers of two “crossover” scFv fragments in which the VH and VL of the two antibodies are present on different polypeptide chains. Diabodies are described more fully in, for example, EP 404,097; WO 93 / 11161; and Hollinger et al., Proc. Natl. Acad. Sci. USA, 90:6444-6448 (1993).

[0103] ‘ ‘Humanized” forms of non-human (e.g., rodent) antibodies are chimeric antibodies that contain minimal sequence derived from the non-human antibody. For the most part, humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a CDR of the recipient are replaced by residues from a CDR of a non-human species (donor antibody) such as mouse, rat, rabbit or non-human primate having the desired antibody specificity, affinity, andcapability. In some instances, FR residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, humanized antibodies can comprise residues that are not found in the recipient antibody or in the donor antibody. These modifications are made to further refine antibody performance (e.g., affinity for the target antigen). In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervariable loops correspond to those of a non-human immunoglobulin and all or substantially all of the FRs are those of a human immunoglobulin sequence. The humanized antibody optionally also will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. For further details, see Jones et al., Nature 321:522-525 (1986); Riechmann et al., Nature 332:323-329 (1988); and Presta, Curr. Op. Struct. Biol. 2:593-596 (1992).

[0104] ‘ ‘Percent (%) amino acid sequence identity” with respect to the polypeptide and antibody sequences identified herein is defined as the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in the polypeptide being compared, after aligning the sequences considering any conservative substitutions as part of the sequence identity. Alignment for purposes of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software such as BLAST, BLAST-2, ALIGN, MegAlign (DNASTAR), or MUSCLE software. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the full-length of the sequences being compared. For purposes herein, however, % amino acid sequence identity values are generated using the sequence comparison computer program MUSCLE (Edgar, R.C., Nucleic Acids Research 32(5): 1792- 1797 , 2004; Edgar, R.C., BMC Bioinformatics 5(1): 113, 2004).

[0105] The terms “Fc receptor” or “FcR” are used to describe a receptor that binds to the Fc region of an antibody. In some embodiments, an FcR is one that binds an IgG antibody (a y receptor) and includes receptors of the FcyRI, FcyRII, and FcyRIII subclasses, including allelic variants and alternatively spliced forms of these receptors. FcyRII receptors include FcyRIIA (an “activating receptor”) and FcyRIIB (an “inhibiting receptor”), which have similar amino acid sequences that differ primarily in the cytoplasmic domains thereof. Activating receptor FcyRIIA contains an immunoreceptor tyrosine-based activation motif (IT AM) in its cytoplasmic domain. Inhibiting receptor FcyRIIB contains an immunoreceptor tyrosine-based inhibition motif (ITIM)in its cytoplasmic domain (see review Daeron, M., Annu. Rev. Immunol. 15:203-234 (1997)). The term includes allotypes, such as FcyRIIIA allotypes: FcyRIIIA-Phel58, FcyRIIIA-Vall58, FcyRIIA-R131 and / or FcyRIIA-H131. FcRs are reviewed in Ravetch and Kinet, Annu. Rev. Immunol 9:457-92 (1991); Capel et al., Immunomethods 4:25-34 (1994); and de Haas et al., J. Lab. Clin. Med. 126:330-41 (1995). Other FcRs, including those to be identified in the future, are encompassed by the term “FcR” herein. The term also includes the neonatal receptor, FcRn, which is responsible for the transfer of maternal IgGs to the fetus (Guyer et al., J. Immunol. 117:587 (1976) and Kim et al., J. Immunol. 24:249 (1994)).

[0106] The term “FcRn” refers to the neonatal Fc receptor (FcRn). FcRn is structurally similar to the proteins of the MHC and consists of an cx-chain noncovalently bound to |32-microglobulin. The multiple functions of the neonatal Fc receptor FcRn are reviewed in Ghetie and Ward (2000) Annu. Rev. Immunol. 18, 739-766. FcRn plays a role in the passive delivery of immunoglobulin IgGs from mother to young and the regulation of serum IgG levels. FcRn can act as a salvage receptor, binding and transporting pinocytosed IgGs in intact form both within and across cells, and rescuing them from a default degradative pathway.

[0107] The “CHI domain” of a human IgG Fc region (also referred to as “Cl” of “Hl” domain) usually extends from about amino acid 118 to about amino acid 215 (EU numbering system).

[0108] The “hinge region” is generally defined as stretching from Glu216 to Pro230 of human IgGl (Burton, Molec. Immunol.22:161-2Q6 (1985)). Hinge regions of other IgG isotypes may be aligned with the IgGl sequence by placing the first and last cysteine residues forming interheavy chain S-S bonds in the same positions.

[0109] The “CH2 domain” of a human IgG Fc region (also referred to as “C2” of “H2” domain) usually extends from about amino acid 231 to about amino acid 340. The CH2 domain is unique in that it is not closely paired with another domain. Rather, two N-linked branched carbohydrate chains are interposed between the two CH2 domains of an intact native IgG molecule. It has been speculated that the carbohydrate may provide a substitute for the domain-domain pairing and help stabilize the CH2 domain. Burton, Molec Immunol. 22:161-206 (1985).

[0110] The “CH3 domain” (also referred to as “C2” or “H3” domain) comprises the stretch of residues C-terminal to a CH2 domain in an Fc region (i.e. from about amino acid residue 341 to the C-terminal end of an antibody sequence, typically at amino acid residue 446 or 447 of an IgG).

[0111] A “functional Fc fragment” possesses an “effector function” of a native sequence Fc region. Exemplary “effector functions” include Clq binding; complement dependent cytotoxicity (CDC); Fc receptor binding; antibody-dependent cell-mediated cytotoxicity (ADCC); phagocytosis; down regulation of cell surface receptors (e.g., B cell receptor; BCR), etc. Such effector functions generally require the Fc region to be combined with a binding domain (e.g., an antibody variable domain) and can be assessed using various assays known in the art.

[0112] An antibody with a variant IgG Fc with “altered” FcR binding affinity or ADCC activity is one which has either enhanced or diminished FcR binding activity (e.g., FcyR or FcRn) and / or ADCC activity compared to a parent polypeptide or to a polypeptide comprising a native sequence Fc region. The variant Fc which “exhibits increased binding” to an FcR binds at least one FcR with higher affinity (e.g., lower apparent Kd or IC50 value) than the parent polypeptide or a native sequence IgG Fc. According to some embodiments, the improvement in binding compared to a parent polypeptide is about 3-fold, such as about any of 5, 10, 25, 50, 60, 100, 150, 200, or up to 500-fold, or about 25% to 1000% improvement in binding. The polypeptide variant which “exhibits decreased binding” to an FcR, binds at least one FcR with lower affinity (e.g., higher apparent Kd or higher IC50 value) than a parent polypeptide. The decrease in binding compared to a parent polypeptide may be about 40% or more decrease in binding.

[0113] “Antibody-dependent cell-mediated cytotoxicity” or “ADCC” refers to a form of cytotoxicity in which secreted Ig bound to Fc receptors (FcRs) present on certain cytotoxic cells (e.g., Natural Killer (NK) cells, neutrophils, and macrophages) enable these cytotoxic effector cells to bind specifically to an antigen-bearing target cell and subsequently kill the target cell with cytotoxins. The antibodies “arm” the cytotoxic cells and are absolutely required for such killing. The primary cells for mediating ADCC, NK cells, express FcyRIII only, whereas monocytes express FcyRI, FcyRII and FcyRIII. FcR expression on hematopoietic cells is summarized in Table 3 on page 464 of Ravetch and Kinet, Annu. Rev. Immunol 9:457-92 (1991). To assess ADCC activity of a molecule of interest, an in vitro ADCC assay, such as that described in US Patent No. 5,500,362 or 5,821,337 may be performed. Useful effector cells for such assays include peripheral blood mononuclear cells (PBMC) and NK cells. Alternatively, or additionally, ADCC activity of the molecule of interest may be assessed in vivo, e.g., in an animal model such as that disclosed in Clynes et al. PNAS (USA) 95:652-656 (1998).

[0114] The polypeptide comprising a variant Fc region which “exhibits increased ADCC” or mediates ADCC in the presence of human effector cells more effectively than a polypeptide having wild-type IgG Fc or a parent polypeptide is one which in vitro or in vivo is substantially more effective at mediating ADCC, when the amounts of polypeptide with variant Fc region and the polypeptide with wild- type Fc region (or the parent polypeptide) in the assay are essentially the same. Generally, such variants will be identified using any in vitro ADCC assay known in the art, such as assays or methods for determining ADCC activity, e.g., in an animal model etc. In some embodiments, the variant is from about 5-fold to about 100-fold, e.g., from about 25- fold to about 50-fold, more effective at mediating ADCC than the wild-type Fc (or parent polypeptide).

[0115] “Complement dependent cytotoxicity” or “CDC” refers to the lysis of a target cell in the presence of complement. Activation of the classical complement pathway is initiated by the binding of the first component of the complement system (Clq) to antibodies (of the appropriate subclass) which are bound to their cognate antigen. To assess complement activation, a CDC assay, e.g., as described in Gazzano-Santoro et al., J. Immunol. Methods 202:163 (1996), may be performed. Polypeptide variants with altered Fc region amino acid sequences and increased or decreased Clq binding capability are described in US patent No. 6, 194,55 IB 1 and WO99 / 51642. The contents of those patent publications are specifically incorporated herein by reference. See, also, Idusogie et al. J. Immunol. 164: 4178-4184 (2000).

[0116] Unless otherwise specified, a “nucleotide sequence encoding an amino acid sequence” includes all nucleotide sequences that are degenerate versions of each other and that encode the same amino acid sequence. The phrase nucleotide sequence that encodes a protein or an RNA may also include introns to the extent that the nucleotide sequence encoding the protein may, in some version, contain an intron(s).

[0117] The term “operably linked” refers to functional linkage between a regulatory sequence and a heterologous nucleic acid sequence resulting in expression of the latter. For example, a first nucleic acid sequence is operably linked with a second nucleic acid sequence when the first nucleic acid sequence is placed in a functional relationship with the second nucleic acid sequence. For instance, a promoter is operably linked to a coding sequence if the promoter affects the transcription or expression of the coding sequence. Generally, operably linked DNA sequences are contiguous and, where necessary to join two protein coding regions, in the same reading frame.

[0118] “Homologous” refers to the sequence similarity or sequence identity between two polypeptides or between two nucleic acid molecules. When a position in both of the two compared sequences is occupied by the same base or amino acid monomer subunit, e.g., if a position in each of two DNA molecules is occupied by adenine, then the molecules are homologous at that position. The percent homology between two sequences is a function of the number of matching or homologous positions shared by the two sequences divided by the number of positions compared times 100. For example, if 6 of 10 of the positions in two sequences are matched or homologous then the two sequences are 60% homologous. By way of example, the DNA sequences ATTGCC and TATGGC share 50% homology. Generally, a comparison is made when two sequences are aligned to give maximum homology.

[0119] An “effective amount” of an anti-MSLN construct or composition as disclosed herein, is an amount sufficient to carry out a specifically stated purpose. An “effective amount” can be determined empirically and by known methods relating to the stated purpose.

[0120] The term “therapeutically effective amount” refers to an amount of an anti-MSLN construct or composition as disclosed herein, effective to “treat” a disease or disorder in an individual. In the case of cancer, the therapeutically effective amount of the anti-MSLN construct or composition as disclosed herein can reduce the number of cancer cells; reduce the tumor size or weight; inhibit (z.e., slow to some extent and preferably stop) cancer cell infiltration into peripheral organs; inhibit (z.e., slow to some extent and preferably stop) tumor metastasis; inhibit, to some extent, tumor growth; and / or relieve to some extent one or more of the symptoms associated with the cancer. To the extent the anti-MSLN construct or composition as disclosed herein can prevent growth and / or kill existing cancer cells, it can be cytostatic and / or cytotoxic. In some embodiments, the therapeutically effective amount is a growth inhibitory amount. In some embodiments, the therapeutically effective amount is an amount that extends the survival of a patient. In some embodiments, the therapeutically effective amount is an amount that improves progression free survival of a patient.

[0121] As used herein, by “pharmaceutically acceptable” or “pharmacologically compatible” is meant a material that is not biologically or otherwise undesirable, e.g., the material may be incorporated into a pharmaceutical composition administered to a patient without causing any significant undesirable biological effects or interacting in a deleterious manner with any of the other components of the composition in which it is contained. Pharmaceutically acceptable carriers or excipients have preferably met the required standards of toxicological andmanufacturing testing and / or are included on the Inactive Ingredient Guide prepared by the U.S. Food and Drug administration.

[0122] The term “label” when used herein refers to a detectable compound or composition which can be conjugated directly or indirectly to the anti-MSLN antibody moiety. The label may be detectable by itself (e.g., radioisotope labels or fluorescent labels) or, in the case of an enzymatic label, may catalyze chemical alteration of a substrate compound or composition which is detectable.

[0123] The term "specific binding" or "specifically binds to" or is "specific for" a particular polypeptide or an epitope on a particular polypeptide target as used herein can be exhibited, for example, by a molecule having a Kd for the target of at least about 10'4M, alternatively at least about 10'5M, alternatively at least about 10'6M, alternatively at least about 10'7M, alternatively at least about 10'8M, alternatively at least about 10'9M, alternatively at least about IO'10M, alternatively at least about 10'11M, alternatively at least about 10'12M, or less. In some embodiments, the term "specific binding" refers to binding where a molecule binds to a particular antigen (e.g., an MSLN ECD) without substantially binding to any other polypeptide or polypeptide epitope.

[0124] The term “chimeric antigen receptor (CAR)”, as used herein, refers to an artificially constructed hybrid single-chain protein or single-chain polypeptide containing an extracellular target-binding (e.g., antigen-binding) domain, linked directly or indirectly to a transmembrane domain (“TM domain”, e.g., the transmembrane domain of a costimulatory molecule), which is in turn linked directly or indirectly to an intracellular signaling domain (ISD) comprising a primary immune cell signaling domain (e.g., one involved in T cell or NK cell activation). The extracellular target-binding domain can be a single-chain variable fragment derived from an antibody (scFv). In addition to scFvs, other single chain antigen binding domains can be used in CAR, e.g., tandem scFvs, single-domain antibody fragments (VHHS or sdAbs), single domain bispecific antibodies (BsAbs), intrabodies, nanobodies, immunokines in a single chain format, and Fab, Fab’, or (Fab’ in single chain formats. The extracellular target-binding domain can be joined to the TM domain via a flexible hinge / spacer region. The ISD comprises a primary signaling sequence, or primary immune cell signaling sequence, which can be from an antigendependent, TCR-associated T cell activation molecule, e.g., a portion of the intracellular domain of CD3^ (TCRQ, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, or CD66d. The ISD can further comprise a costimulatory signaling sequence; e.g., a portion of the intracellulardomain of an antigen-independent, costimulatory molecule such as CD27, CD28, 4- IBB (CD137), 0X40, CD30, CD40, PD-1, ICOS, lymphocyte function- associated antigen-1 (LFA-1), CD2, CD7, LIGHT, NKG2C, B7-H3, a ligand that specifically binds CD83, DaplO, or the like. Characteristics of CARs include their ability to redirect immune cell (e.g., T cell or NK cell) specificity and reactivity toward a selected target in either MHC-restricted (in cases of TCR- mimic antibodies) or non-MHC-restricted (in cases of antibodies against cell surface proteins) manners, exploiting the antigen-binding properties of monoclonal antibodies. The non-MHC- restricted antigen recognition gives immune cells (e.g., T cells or NK cells) expressing CARs the ability to recognize antigen independent of antigen processing, thus bypassing a major mechanism of tumor escape.

[0125] There are currently three generations of CARs. The “first generation” CARs are typically single-chain polypeptides composed of an scFv as the antigen-binding domain fused to a transmembrane domain fused to the cytoplasmic / intracellular domain, which comprises a primary immune cell signaling sequence such as the intracellular domain from the CD3(^ chain, which is the primary transmitter of signals from endogenous TCRs. The “first generation” CARs can provide de novo antigen recognition and cause activation of both CD4+and CD8+T cells through their CD3(^ chain signaling domain in a single fusion molecule, independent of HLA- mediated antigen presentation. The “second generation” CARs add intracellular domains from various costimulatory molecules (e.g., CD28, 4- IBB, ICOS, 0X40) to the primary immune cell signaling sequence of the CAR to provide additional signals to the T cell. Thus, the “second generation” CARs comprise fragments that provide costimulation (e.g., CD28 or 4-IBB) and activation (e.g., CD3Q. Preclinical studies have indicated that the “second generation” CARs can improve the antitumor activity of T cells.

[0126] The “third generation” CARs comprise those that provide multiple costimulation (e.g., CD28 and 4- IBB) and activation (e.g., CD3Q.

[0127] Examples of CAR T therapies are described, see, e.g., US Patent No. 10,221,245 describing CAR CTL019 which has an anti-CD19 extracellular target-binding domain, a transmembrane domain from CD8, a costimulatory domain from 4- IBB, and a primary signaling domain from CD3^, as well as US Patent No. 9,855,298 which describes a CAR having an anti- CD19 extracellular target-binding domain, a costimulatory domain from CD28, and a primary signaling domain from CD3^.

[0128] As used herein, the term “chimeric antibody-T cell receptor” or “caTCR” construct refers to a functional multi-chain polypeptide complex comprising one or more antibody moieties linked to a T cell receptor module (TCRM) derived from transmembrane domains and optionally intracellular domains of T cell receptor (TCR) chains, such as TCRcx / p or TCRy / 8 chains. Upon binding of the one or more antibody moieties to the target(s), the TCRM associates with at least one TCR-associated signaling module, such as CD3y, CD35, CD3s, and / or CD3(^. caTCRs can be monospecific or multispecific. Suitable antibody moieties include, but are not limited to, an Fv, a Fab, and an scFv. Various constructs of caTCRs have been described, for example, see US 10822413, which is incorporated herein by reference in its entirety. In some embodiments, a caTCR comprises a first polypeptide chain comprising an antibody heavy chain variable region (VH), a first transmembrane domain and a first intracellular domain derived from a first T cell receptor chain, and a second polypeptide chain comprising an antibody light chain variable region (VL), a second transmembrane domain and a second intracellular domain derived from a second TCR chain, wherein the VH and the VL associate with each other to form an antigen binding domain that specifically binds a target. In some embodiments, the first polypeptide comprises a first antibody constant region (e.g., CHI) and the second polypeptide comprises a second antibody constant region (e.g., CL). In some embodiments, the first polypeptide and the second polypeptide do not comprise antibody constant regions. In some embodiments, a caTCR does not comprise a primary immune cell signaling sequence (e.g., a portion of the intracellular domain of CD3y, CD35, CD3s, or CD3Q. In some embodiments, a caTCR does not include a functional primary immune cell signaling sequence. In some embodiments, an anti-MSLN caTCR comprises a) an extracellular domain comprising an anti- MSLN antibody moiety that specifically binds to an MSLN ECD, such as an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2, and b) a TCRM capable of associating with at least one TCR-associated signaling module. The terms “chimeric antibody-T cell receptor” (caTCR) and “antibody-T cell receptor” or “antibody / T-cell receptor” chimeric molecule or construct (abTCR or AbTCR) are used interchangeably herein. Further descriptions and examples of caTCR and abTCR may be found in, e.g., US 2019 / 0248865 and US 2021 / 0101954, the contents of which are incorporated by reference herein in their entirety.

[0129] The terms “chimeric stimulatory receptor” or “CSR” refers to an artificially constructed receptor comprising a target-binding domain linked directly or indirectly to a transmembrane domain, and an intracellular signaling domain derived from one or more co-stimulatorymolecules of an immune cell, wherein the intracellular signaling domain does not comprise a primary immune cell signaling sequence or a functional primary immune cell signaling sequence, such as a CD3^ signaling sequence or a functional CD3^ signaling sequence. In some embodiments, the transmembrane domain of a CSR is not a transmembrane domain of a TCR or a derivative thereof. In nature, activation of effector immune cells (e.g., T cells) typically require a primary signal through antigen- specific receptors (e.g., TCR) on the effector immune cell and a secondary signal provided by the interaction between co- stimulatory molecules expressed on the membrane of antigen presenting cells and effector immune cells. Upon target binding, a CSR can send a secondary signal that regulates activation of immune cells, e.g., T cells. The targetbinding domain in a CSR may be an antibody moiety or an extracellular domain of a receptor.

[0130] As used herein, “primary immune cell signaling sequences” refer to sequences that act in a stimulatory manner may contain signaling motifs which are known as immunoreceptor tyrosine-based activation motifs or IT AMs. Examples of ITAM-containing primary immune cell signaling sequences include those derived from CD3(^ (TCRQ, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, and CD66d. A “functional” primary immune cell signaling sequence is a sequence that is capable of transducing an immune cell activation signal when operably coupled to an appropriate receptor. “Non-functional” primary immune cell signaling sequences, which may comprise fragments or variants of primary immune cell signaling sequences, are unable to transduce an immune cell activation signal.

[0131] It is understood that embodiments of the present application described herein include “consisting of’ and / or “consisting essentially of’ embodiments.

[0132] Reference to “about” a value or parameter herein includes (and describes) variations that are directed to that value or parameter per se. For example, description referring to “about X” includes description of “X”.

[0133] As used herein, reference to “not” a value or parameter generally means and describes “other than” a value or parameter. For example, the method is not used to treat cancer of type X means the method is used to treat cancer of types other than X.

[0134] As used herein, a "control" is an alternative sample used in an experiment for comparison purpose. A control can be "positive" or "negative." For example, where the purpose of the experiment is to determine a correlation of the efficacy of a therapeutic agent for the treatment for a particular type of disease, a positive control (a compound or composition knownto exhibit the desired therapeutic effect) and a negative control (a subject or a sample that does not receive the therapy or receives a placebo) are typically employed.

[0135] As used herein, the terms “subject”, “patient”, or “individual” can be an individual organism, a vertebrate, a mammal, or a human. In some embodiments, the subject, patient or individual is a human.Anti-MSLN Constructs

[0136] In one aspect, the present application provides MSLN ECD-specific constructs (anti- MSLN constructs) that comprise an antibody moiety that specifically binds to a mesothelin (MSLN) extracellular domain (ECD) (anti-MSLN antibody). In some embodiments, the anti- MSLN construct is an isolated anti-MSLN construct. The specificity of the anti-MSLN construct derives from an anti-MSLN antibody moiety, such as a full-length antibody or antigen-binding fragment thereof that specifically binds to MSLN. In some embodiments, the MSLN ECD comprises the amino acid sequence of SEQ ID NO: 2.

[0137] Anti-MSLN constructs within the scope of the present application include, without limitation, e.g., full-length anti-MSLN antibodies, multispecific anti-MSLN constructs, anti- MSLN chimeric antigen receptors (CARs), anti-MSLN chimeric antibody-T cell receptor constructs (caTCRs), anti-MSLN chimeric signaling receptors (CSRs), anti-MSLN immunoconjugates, and others, as described herein below. In some embodiments, the anti- MSLN construct is bispecific.

[0138] Lor example, in some embodiments, the anti-MSLN construct comprises an anti-MSLN antibody moiety that specifically binds to an MSLN ECD expressed on the surface of a cell, such as a cancer cell. In some embodiments, the extent of binding of the anti-MSLN antibody to a non-target polypeptide is less than about 10% of the binding of the anti-MSLN antibody moiety to an MSLN as determined by methods known in the art, such as enzyme-linked immunosorbent assay (ELISA), fluorescence activated cell sorting (LACS) analysis, a radioimmunoprecipitation assay (RIA), bio-layer interferometry (BLI) or surface plasmon resonance (SPR) Specific binding can be measured, for example, by determining binding of a molecule compared to binding of a control molecule, which generally is a molecule of similar structure that does not have binding activity. Lor example, specific binding can be determined by competition with a control molecule that is similar to the target, for example, an excess ofunlabeled target. In this case, specific binding is indicated if the binding of the labeled target to a probe is competitively inhibited by excess unlabeled target.

[0139] For example, in some embodiments, there is provided an anti-MSLN construct comprising an anti-MSLN antibody moiety that specifically binds to an MSLN ECD. In some embodiments, the MSLN ECD comprises (such as consists of) the amino acid sequence of SEQ ID NO: 2. In some embodiments, the anti-MSLN construct is non-naturally occurring. In some embodiments, the anti-MSLN construct is or comprises an anti-MSLN antibody moiety, wherein the anti-MSLN antibody moiety is a full-length antibody. In some embodiments, the anti-MSLN construct is a multispecific (such as bispecific) molecule. In some embodiments, the anti-MSLN construct is a chimeric receptor (e.g., a CAR, caTCR, CSR). In some embodiments, the anti- MSLN construct is an immunoconjugate. In some embodiments, the anti-MSLN construct binds the MSLN with a Kd between about 0.1 pM to about 500 nM (such as about any of 0.1 pM, 1.0 pM, 10 pM, 50 pM, 100 pM, 500 pM, 1 nM, 10 nM, 50 nM, 100 nM, or 500 nM, including any ranges between these values).

[0140] In some embodiments, the anti-MSLN construct comprises any one of the anti-MSLN antibody moieties described in the “Anti-MSLN antibody moieties” section below. In some embodiments, the anti-MSLN construct is non-naturally occurring. In some embodiments, the anti-MSLN construct is or comprises an anti-MSLN antibody moiety, wherein the anti-MSLN antibody moiety is a full-length antibody. In some embodiments, the anti-MSLN construct is a multispecific (such as bispecific) molecule. In some embodiments, the anti-MSLN construct is a chimeric receptor (e.g., an anti-MSLN CAR, caTCR, CSR). In some embodiments, the anti- MSLN construct is an immunoconjugate.

[0141] In some embodiments, the anti-MSLN the anti-MSLN antibody moiety is a first anti- MSLN antibody moiety, and wherein the anti-MSLN construct further comprises a second anti- MSLN antibody moiety. In some embodiments, the first anti-MSLN antibody moiety specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2. In some embodiments, the second anti-MSLN antibody moiety specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2. In some embodiments, the second anti-MSLN antibody moiety is identical to the first anti-MSLN antibody moiety. In some embodiments, the second anti-MSLN antibody moiety is different from the first anti-MSLN antibody moiety. In some embodiments, the second anti-MSLN antibody moiety specifically binds to a different region of an MSLN ECD (e.g., an MSLN ECD that comprises the aminoacid sequence of SEQ ID NO: 2) than the region of the MSLN ECD that is specifically bound by the first anti-MSLN antibody moiety. In some embodiments, the second anti-MSLN antibody moiety specifically binds to the same region of an MSLN ECD (e.g., an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2) as the region of the MSLN ECD that is specifically bound by the first anti-MSLN antibody moiety, but specifically binds an epitope that is non-overlapping with the epitope specifically bound by the first anti-MSLN antibody moiety.

[0142] In some embodiments, the anti-MSLN construct comprises an anti-MSLN antibody moiety that specifically binds an MSLN ECD (e.g. , an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2), and further comprises at least one other antibody moiety that specifically binds to at least one other target which is not MSLN ECD. Lor example, in some embodiments the anti-MSLN construct comprises any one of the anti-MSLN antibody moieties described in the “Anti-MSLN antibody moieties” section below, and further comprises at least one other antibody moiety that specifically binds to at least one other target which is not MSLN ECD. In some embodiments, the at least one other target is expressed on a cancer cell. In some embodiments, the at least one other target is expressed on a mesothelioma, epithelioid mesothelioma, malignant pleural mesothelioma, pancreatic cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, ovarian cancer, ovarian serous adenocarcinoma, endometrial cancer, cervical cancer, lung adenocarcinoma, non- small cell lung cancer, AML, CLL, melanoma, gastrointestinal cancer, breast cancer (including metastatic breast cancer), glioma, prostate cancer, or a biliary cancer cell. In some embodiments, the at least one other target is a cell-surface antigen selected from the group consisting of ROR1, ROR2, EpCAM, MUC1, MUC16, ERa, RORA, EGER, GPRC5D, GPC3, HER2, HER3, DLL3, c-Met, BCMA, CD19, CD22, EGPRvIII, PSMA, and p53. In some embodiments, the at least one other target is complex comprising an antigenic peptide and an MHC class I protein (an antigenic peptide / MHC class I complex), wherein the antigenic peptide is derived from a protein selected from the group consisting of MSLN, WT1, NDC80, KRAS, ALP, NY-ESO-1, HPV16-E7, PRAME, PSA, and Histone H3.3.Anti-MSLN Antibody Moieties

[0143] The anti-MSLN constructs comprise an anti-MSLN antibody moiety that specifically binds to an MSLN ECD (e.g., SEQ ID NO: 2).

[0144] In some embodiments, the anti-MSLN antibody moiety specifically binds to an MSLN ECD present on the surface of a cell. In some embodiments, the cell is a cancer cell. In some embodiments, the cancer cell is in a solid tumor. In some embodiments, the cancer cell is in a liquid tumor. In some embodiments, the cancer cell is a metastatic cancer cell.

[0145] In some embodiments, the anti-MSLN antibody moiety is a full-length antibody. In some embodiments, the anti-MSLN antibody moiety is an antigen-binding fragment, for example an antigen-binding fragment selected from the group consisting of a Lab, a Lab', a E(ab')2, an Ev fragment, a disulfide stabilized Ev fragment (dsFv), and a single-chain antibody molecule (scFv). In some embodiments, the anti-MSLN antibody moiety is an scFv. In some embodiments, the anti-MSLN antibody moiety is human, humanized, or semi-synthetic.

[0146] In some embodiments, the anti-MSLN antibody moiety of the anti-MSLN construct is fused to an Fc fragment, optionally via a linker. In some embodiments, the Fc fragment is an IgG Fc fragment. In some embodiments, the IgG is an IgGl, IgG2, IgG3, or IgG4.

[0147] In some embodiments, the anti-MSLN antibody moiety of the anti-MSLN construct is an antigen-binding fragment of an anti-MSLN antibody, for example, an antigen-binding fragment selected from the group consisting of a Fab, a Fab', a F(ab')2, an Fv fragment, a dsFv, and an scFv. In some embodiments, the anti-MSLN antibody moiety of the anti-MSLN construct is an scFv. In some embodiments, the anti-MSLN antibody moiety is human, humanized, or semi- synthetic.

[0148] In some embodiments, the anti-MSLN construct comprises an anti-MSLN antibody moiety that binds a human MSLN ECD, a mouse MSLN ECD, a rat MSLN ECD, a cynomolgus monkey MSLN ECD, and / or a rhesus MSLN ECD. In some embodiments, the anti-MSLN construct comprises an anti-MSLN antibody moiety that specifically binds a human MSLN ECD. In some embodiments, the anti-MSLN construct comprises an anti-MSLN antibody moiety that specifically binds to an MSLN ECD present on or expressed on the surface of a cell. In some embodiments, the cell is a cancer cell. In some embodiments, the cell expresses significantly higher levels of MSLN (e.g., an MSLN ECD) as compared to a reference cell. In some embodiments, the reference cell is a cell obtained from or derived from non-diseased (such as non-cancerous) tissue. In some embodiments, the cell that expresses abnormally high levels of MSLN is a cancer cell. In some embodiments, the cancer cell is a solid tumor cancer cell or a hematological cancer cell. In some embodiments, the solid tumor cancer cell is a mesothelioma, epithelioid mesothelioma, malignant pleural mesothelioma, pancreatic cancer, pancreaticadenocarcinoma, pancreatic ductal adenocarcinoma, ovarian cancer, ovarian serous adenocarcinoma, endometrial cancer, cervical cancer, lung adenocarcinoma, non-small cell lung cancer, melanoma, gastrointestinal cancer, breast cancer (including metastatic breast cancer), glioma, prostate cancer, or biliary cancer cell. In some embodiments, the hematological cancer cell is leukemia, such as AML or CLL. In some embodiments, the cancer cell is a metastatic cancer cell.

[0149] In some embodiments, the anti-MSLN antibody moiety (or the anti-MSLN construct comprising the anti-MSLN antibody moiety) binds to an MSLN ECD with a Kd between about 0.1 pM to about 500 nM (such as about any of 0.1 pM, 1.0 pM, 10 pM, 50 pM, 100 pM, 500 pM, 1 nM, 10 nM, 50 nM, 100 nM, or 500 nM, including any ranges between these values). In some embodiments, the anti-MSLN antibody moiety (or the anti-MSLN construct comprising the anti- MSLN antibody moiety) binds to an MSLN ECD with a Kd between about 1 pM to about 250 pM (such as about any of 1, 10, 25, 50, 75, 100, 150, 200, or 250 pM, including any ranges between these values). In some embodiments, the anti-MSLN antibody moiety (or the anti- MSLN construct comprising the anti-MSLN antibody moiety) binds to an MSLN ECD with a Kd between about 1 nM to about 500 nM (such as about any of 1, 10, 25, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, or 500 nM, including any ranges between these values).

[0150] In some embodiments, the anti-MSLN antibody moiety is a semi-synthetic antibody moiety comprising fully human sequences and one or more synthetic regions. In some embodiments, the anti-MSLN antibody moiety is a semi- synthetic antibody moiety comprising a fully human VL and a semi- synthetic VH comprising fully human FR1, HC-CDR1, FR2, HC- CDR2, FR3, and FR4 regions and a synthetic HC-CDR3. In some embodiments, the semisynthetic VH comprises a fully synthetic HC-CDR3 having a sequence from about 5 to about 25 (such as about any of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25) amino acids in length. In some embodiments, the semi-synthetic VH or the synthetic HC-CDR3 is obtained from a semi-synthetic library (such as a semi-synthetic human library) comprising fully synthetic HC-CDR3s having a sequence from about 5 to about 25 (such as about any of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25) amino acids in length, wherein each amino acid in the sequence is randomly selected from the standard human amino acids, minus cysteine. In some embodiments, the synthetic HC-CDR3 is from about 7 to about 15 (such as about any of 7, 8, 9, 10, 11, 12, 13, 14, or 15) amino acids in length.

[0151] The anti-MSLN antibody moieties in some embodiments comprise specific sequences or certain variants of such sequences. In some embodiments, the amino acid substitutions in the variant sequences do not substantially reduce the ability of the anti-MSLN antibody moiety to bind the MSLN ECD. For example, alterations that do not substantially reduce MSLN ECD- binding affinity may be made. Alterations that substantially improve MSLN CD-binding affinity or affect some other property, such as specificity and / or cross -reactivity with related variants of the MSLN ECD, are also contemplated.

[0152] In some embodiments, the anti-MSLN antibody moiety specifically binds to an MSLN ECD (e.g., an MLSN ECD comprising the amino acid sequence of SEQ ID NO: 2 expressed on the surface of a cell, such as a cancer cell) and competes for binding to an MSLN ECD with a second anti-MSLN antibody (or anti-MSLN antibody moiety) comprising: (a) an HC-CDR1 comprising the amino acid sequence of any one SEQ ID NOs: 3, 19, 35, 51, 69, 85, 117, 134, 150, and 242, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 20, 36, 52, 70, 86, 102, 118, 135, 151, and 166, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 5, 21, 37, 53, 71, 87, 103, 119, 136, 152, 153, 167, and 364, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) a LC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 6, 22, 38, 54, 72, 88, 104, 120, 137, and 365, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC- CDR2 comprising the amino acid sequence of any one of GAS, GNN, RNN, STT, DAS, SAS, HNS, AAS, and NNN, or a variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 7, 23, 39, 55, 73, 89, 105, 121, 138, 154, 168, 244, and 366, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions.

[0153] In some embodiments, the anti-MSLN antibody moiety specifically binds to a MSLN and competes for binding to MSLN with a second anti-MSLN antibody (or anti-MSLN antibody moiety) that specifically binds an MSLN ECD (e.g., an MLSN ECD comprising the amino acid sequence of SEQ ID NO: 2 expressed on the surface of a cell, such as a cancer cell) and comprises: (a) an HC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 3, 19, 35, 51, 69, 85, 117, 134, 150, and 242; (b) an HC-CDR2 comprising the amino acidsequence of any one of SEQ ID NOs: 4, 20, 36, 52, 70, 86, 102, 118, 135, 151, and 166; (c) an HC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 5, 21, 37, 53, 71, 87, 103, 119, 136, 152, 153, 167, and 364; (d) a LC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 6, 22, 38, 54, 72, 88, 104, 120, 137, and 365; (e) an LC-CDR2 comprising the amino acid sequence of any one of GAS, GNN, RNN, STT, DAS, SAS, HNS, AAS, and NNN; and (f) an LC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 7, 23, 39, 55, 73, 89, 105, 121, 138, 154, 168, 244, and 366.

[0154] In some embodiments, the anti-MSLN antibody moiety comprises one, two, three, four, five, or six CDR sequences selected from the group consisting of: (a) an HC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 3, 19, 35, 51, 69, 85, 117, 134, 150, and 242, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 20, 36, 52, 70, 86, 102, 118, 135, 151, and 166, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 5, 21, 37, 53, 71, 87, 103, 119, 136, 152, 153, 167, and 364, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 6, 22, 38, 54, 72, 88, 104, 120, 137, and 365, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of any one of GAS, GNN, RNN, STT, DAS, SAS, HNS, AAS, and NNN, or a variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 7, 23, 39, 55, 73, 89, 105, 121, 138, 154, 168, 244, and 366, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions.

[0155] In some embodiments, the anti-MSLN construct comprises an anti-MSLN antibody moiety that comprises (a) an HC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 3, 19, 35, 51, 69, 85, 117, 134, 150, and 242, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 20, 36, 52, 70, 86, 102, 118, 135, 151, and 166, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 5, 21, 37, 53, 71, 87, 103, 119, 136, 152, 153, 167, and 364, or a variant thereofcomprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC- CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 6, 22, 38, 54, 72, 88, 104, 120, 137, and 365, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of any one of GAS, GNN, RNN, STT, DAS, SAS, HNS, AAS, and NNN, or a variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 7, 23, 39, 55, 73, 89, 105, 121, 138, 154, 168, 244, and 366, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions.

[0156] In some embodiments, the anti-MSLN antibody moiety comprises one, two, three, four, five, or six CDR sequences selected from the group consisting of: (a) an HC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 3, 19, 35, 51, 69, 85, 117, 134, 150, and 242; (b) an HC-CDR2 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 20, 36, 52, 70, 86, 102, 118, 135, 151, and 166; (c) an HC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 5, 21, 37, 53, 71, 87, 103, 119, 136, 152, 153, 167, and 364; (d) an LC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 6, 22, 38, 54, 72, 88, 104, 120, 137, and 365; (e) an LC-CDR2 comprising the amino acid sequence of any one of GAS, GNN, RNN, STT, DAS, SAS, HNS, AAS, and NNN; and (f) an LC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 7, 23, 39, 55, 73, 89, 105, 121, 138, 154, 168, 244, and 366.

[0157] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 3, 19, 35, 51, 69, 85, 117, 134, 150, and 242; (b) an HC-CDR2 comprising the amino acid sequence of any one of SEQ ID NOs: 4, 20, 36, 52, 70, 86, 102, 118, 135, 151, and 166; (c) an HC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 5, 21, 37, 53, 71, 87, 103, 119, 136, 152, 153, 167, and 364; (d) an LC-CDR1 comprising the amino acid sequence of any one of SEQ ID NOs: 6, 22, 38, 54, 72, 88, 104, 120, 137, and 365; (e) an LC-CDR2 comprising the amino acid sequence of any one of GAS, GNN, RNN, STT, DAS, SAS, HNS, AAS, and NNN; and (f) an LC-CDR3 comprising the amino acid sequence of any one of SEQ ID NOs: 7, 23, 39, 55, 73, 89, 105, 121, 138, 154, 168, 244, and 366.

[0158] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, or a variant thereof comprising up toabout 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 5, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 6, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of GAS, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 7, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 3; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 4; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 5; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 6; (e) an LC-CDR2 comprising the amino acid sequence of GAS; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 7, and is alternatively referred to herein as a “Clone A05 anti-MSLN antibody moiety”.

[0159] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 19, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 20, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 21, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 22, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of GNN, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 23, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 19; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 20; (c) an HC-CDR3 comprising the amino acid sequence of SEQ IDNO: 21; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 22; (e) an LC- CDR2 comprising the amino acid sequence of GNN; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 23, and is alternatively referred to herein as a “Clone A09 anti- MSLN antibody moiety”.

[0160] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 35, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 36, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 37, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 38, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of RNN, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 39, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 35; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 36; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 37; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 38; (e) an LC- CDR2 comprising the amino acid sequence of RNN; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 39, and is alternatively referred to herein as a “Clone A10 anti- MSLN antibody moiety”.

[0161] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 52, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 53, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 54, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of STT, orvariant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 55, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 52; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 53; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 54; (e) an LC- CDR2 comprising the amino acid sequence of STT; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 55, and is alternatively referred to herein as a “Clone A13 anti- MSLN antibody moiety”.

[0162] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 69, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 71, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 72, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of DAS, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 73, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 69; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 71; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 72; (e) an LC- CDR2 comprising the amino acid sequence of DAS; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 73, and is alternatively referred to herein as a “Clone A14 anti- MSLN antibody moiety”.

[0163] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 85 or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprisingthe amino acid sequence of SEQ ID NO: 86, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 87, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 88, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of RNN, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 89, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 85; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 86; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 87; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 88; (e) an LC- CDR2 comprising the amino acid sequence of RNN; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 89, and is alternatively referred to herein as a “Clone A15 anti- MSLN antibody moiety”.

[0164] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 69, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 103, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 104, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of SAS, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 105, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 69; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 103; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 104; (e) an LC-CDR2 comprising the amino acid sequence of SAS; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 105, and is alternatively referred to herein as a “Clone A16 anti- MSLN antibody moiety”.

[0165] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 117, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 118, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 119, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 120, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of HNS, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 121, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 117; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 118; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 119; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 120; (e) an LC- CDR2 comprising the amino acid sequence of HNS; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 121, and is alternatively referred to herein as a “Clone A17 anti- MSLN antibody moiety”.

[0166] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 134, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 135, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 136, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of GAS, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions;and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 138, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 134; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 135; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 136; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137; (e) an LC- CDR2 comprising the amino acid sequence of GAS; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 138, and is alternatively referred to herein as a “Clone A24 anti- MSLN antibody moiety”.

[0167] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 150, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 151, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 152, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of AAS, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 154, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 150; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 151; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 152; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137; (e) an LC- CDR2 comprising the amino acid sequence of AAS; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 154, and is alternatively referred to herein as a “Clone A39 anti- MSLN antibody moiety”.

[0168] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 166, or a variant thereof comprising up to about 3 (suchas about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 167, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of AAS, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 168, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 166; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 167; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137; (e) an LC- CDR2 comprising the amino acid sequence of AAS; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 168, and is alternatively referred to herein as a “Clone A44 anti- MSLN antibody moiety”.

[0169] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 242, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 102, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 153, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of AAS, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 244, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 242; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 102; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 153; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137; (e) an LC- CDR2 comprising the amino acid sequence of AAS; and (f) an LC-CDR3 comprising the aminoacid sequence of SEQ ID NO: 244, and is alternatively referred to herein as a “Clone A45 anti- MSLN antibody moiety”.

[0170] In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 52, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 364, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 365, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions; (e) an LC-CDR2 comprising the amino acid sequence of NNN, or variant thereof comprising up to about 2 (such as about any of 1 or 2) amino acid substitutions; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 366, or a variant thereof comprising up to about 3 (such as about any of 1, 2, or 3) amino acid substitutions. In some embodiments, the anti-MSLN antibody moiety comprises: (a) an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51; (b) an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 52; (c) an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 364; (d) an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 365; (e) an LC- CDR2 comprising the amino acid sequence of NNN; and (f) an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 366, and is alternatively referred to herein as a “Clone A46 anti- MSLN antibody moiety”.

[0171] In some embodiments, the anti-MSLN antibody moiety comprises one, two, three, four five, or six CDRs of any one of antibody Clones A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, or A46, as shown in Tables 2A-2B. The sequences of the HC-CDRs from exemplary anti-MSLN antibody Clones A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, and A46 are provided in Table 2A below and the LC-CDRs from exemplary anti- MSLN antibody Clones A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, and A46 are provided in Table 2B below.Table 2A. Anti-MSLN antibody moiety HC-CDR sequences.Table 2B. Anti-MSLN antibody moiety LC-CDR sequences.

[0172] In some embodiments, the anti-MSLN antibody moiety comprises a heavy chain framework region (FR1) comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 8, 24, 40, 56, 74, 90, 106, 122, 139, 155, 169, 245, and 367, a heavy chain FR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 9, 25, 41, 57, 75, 91, 107, 123, 140, 156, 170, 246, and 368, a heavy chain FR3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 10, 26, 42, 58, 76, 92, 108, 124, 141, 157, 171, 247, and 369, and / or a heavy chain FR4 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 11, 27, 43, 59, 77, 93, 109, 125, 142, 158,172, 248, and 370. In some embodiments, the anti-MSLN antibody moiety comprises a light chain FR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 12, 28, 44, 60, 78, 94, 110, 126, 143, 159, 173, 249, and 371, a light chain FR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 13, 29, 45, 61, 79, 95, 111, 127, 144, 160, 174, 250, and 372, a light chain FR3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 14, 30, 46, 62, 80, 96, 112, 128, 145, 161, 175, 251, and 373, and / or a light chain FR4 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 15, 31, 47, 63, 81, 97, 113, 129, 146, 162, 176, 252, and 374.

[0173] In some embodiments, the anti-MSLN antibody moiety comprises one, two, three, four five, six, seven, or eight FRs of any one of antibody Clones A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, or A46. The anti-MSLN antibody moiety FRs of antibody Clones A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, and A46 are shown in Table 3.Table 3. Anti-MSLN antibody moiety FR sequences.

[0174] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an amino acid sequence that is at least about 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence of any one of SEQ ID NOs: 16, 32, 48, 64, 82, 98, 114, 130, 147, 163, 177, 361, and 375, and / or a VL comprising an amino acid sequence that is at least about 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the amino acid sequence of any one of SEQ ID NOs: 17, 33, 49, 65, 83, 99, 115, 131, 148, 164, 178, 362, and 376. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of any one of SEQ ID NOs: 16, 32, 48, 64, 82, 98, 114, 130, 147, 163, 177, 361, and 375, and / or a VL comprising the amino acid sequence of any one of SEQ ID NOs: 17, 33, 49, 65, 83, 99, 115, 131, 148, 164, 178, 362, and 376.

[0175] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 16, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 17. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 16, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 16; and a VL comprising the amino acid sequence of SEQ ID NO: 17, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 17. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 16; and a VL comprising the amino acid sequence of SEQ ID NO: 17, and is alternatively referred to herein as a “Clone A05 anti-MSLN antibody moiety”.

[0176] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 32, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 33. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 32, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 32; and a VL comprising the amino acid sequence of SEQ ID NO: 33, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 33. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 32; and a VL comprising the amino acid sequence of SEQ ID NO: 33, and is alternatively referred to herein as a “Clone A09 anti-MSLN antibody moiety”.

[0177] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 48, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 49. In someembodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 48, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 48; and a VL comprising the amino acid sequence of SEQ ID NO: 49, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 49. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 48; and a VL comprising the amino acid sequence of SEQ ID NO: 49, and is alternatively referred to herein as a “Clone A10 anti-MSLN antibody moiety”.

[0178] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 64, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 65. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 64, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 64; and a VL comprising the amino acid sequence of SEQ ID NO: 65, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 65. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 64; and a VL comprising the amino acid sequence of SEQ ID NO: 65, and is alternatively referred to herein as a “Clone A13 anti-MSLN antibody moiety”.

[0179] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 82, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 83. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 82, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 82; and a VL comprisingthe amino acid sequence of SEQ ID NO: 83, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 83. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 82; and a VL comprising the amino acid sequence of SEQ ID NO: 83, and is alternatively referred to herein as a “Clone A14 anti-MSLN antibody moiety”.

[0180] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 98, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 99. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 98, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 98; and a VL comprising the amino acid sequence of SEQ ID NO: 99, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 99. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 98; and a VL comprising the amino acid sequence of SEQ ID NO: 99, and is alternatively referred to herein as a “Clone A15 anti-MSLN antibody moiety”.

[0181] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 114, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 115. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 114, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 114; and a VL comprising the amino acid sequence of SEQ ID NO: 115, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 115. In some embodiments, the anti-MSLN antibody moiety comprises a VHcomprising the amino acid sequence of SEQ ID NO: 114; and a VL comprising the amino acid sequence of SEQ ID NO: 115, and is alternatively referred to herein as a “Clone A16 anti- MSLN antibody moiety”.

[0182] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 130, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 131. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 130, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 130; and a VL comprising the amino acid sequence of SEQ ID NO: 131, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 131. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 130; and a VL comprising the amino acid sequence of SEQ ID NO: 131, and is alternatively referred to herein as a “Clone A17 anti- MSLN antibody moiety”.

[0183] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 147, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 148. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 147, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 147; and a VL comprising the amino acid sequence of SEQ ID NO: 148, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 148. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 147; and a VL comprising the amino acidsequence of SEQ ID NO: 148, and is alternatively referred to herein as a “Clone A24 anti- MSLN antibody moiety”.

[0184] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 163, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 164. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 163, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 163; and a VL comprising the amino acid sequence of SEQ ID NO: 164, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 164. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 163; and a VL comprising the amino acid sequence of SEQ ID NO: 164, and is alternatively referred to herein as a “Clone A39 anti- MSLN antibody moiety”.

[0185] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 177, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 178. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 177, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 177; and a VL comprising the amino acid sequence of SEQ ID NO: 178, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 178. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 177; and a VL comprising the amino acid sequence of SEQ ID NO: 178, and is alternatively referred to herein as a “Clone A44 anti- MSLN antibody moiety”.

[0186] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 361, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 362. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 361, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 361; and a VL comprising the amino acid sequence of SEQ ID NO: 362, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 362. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 361; and a VL comprising the amino acid sequence of SEQ ID NO: 362, and is alternatively referred to herein as a “Clone A45 anti- MSLN antibody moiety”.

[0187] In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 375, and a VL comprising an LC-CDR1, an LC-CDR2, and an LC- CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 376. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 375, or a variant thereof having at least 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 375; and a VL comprising the amino acid sequence of SEQ ID NO: 376, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 376. In some embodiments, the anti-MSLN antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 375; and a VL comprising the amino acid sequence of SEQ ID NO: 376, and is alternatively referred to herein as a “Clone A46 anti- MSLN antibody moiety”.

[0188] In some embodiments, the anti-MSLN antibody moiety comprises the VH and / or VL of any one of antibody Clones A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, orA46. The anti-MSLN antibody moiety VH and VL of Clones A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, and A46 are shown in Table 4.Table 4. Anti-MSLN antibody moiety VH / VL sequences.

[0189] The VH and VL can be combined in pair-wise combinations to generate additional anti- MSLN antibody moieties that can be incorporated into and / or used with the anti-MSLN constructs of the present disclosure.

[0190] In some embodiments according to any of the anti-MSLN constructs described above, the anti-MSLN antibody moiety can be chimeric, humanized, partially human, fully human, or semi- synthetic. In some embodiments, the anti-MSLN antibody moiety is a full-length antibody, a Fab, a Fab’, a F(ab’)2, an Fv, or an scFv. In some embodiments, the anti-MSLN antibody moiety is an scFv. Exemplary scFv amino acid sequences include, but are not limited to, SEQ IDNOs: 18, 34, 50, 66, 84, 100, 101, 116, 132, 149, 165, 363, and 377. A person of ordinary skill in the art would understand that the VH and VL can be combined in different pair- wise combinations, different orders and linker sequences to generate additional anti-MSLN scFvs that can be incorporated into and / or used with the anti-MSLN constructs of the present disclosure.

[0191] The anti-MSLN antibodies or anti-MSLN antibody moieties may be identified by screening combinatorial libraries for antibodies with the desired activity or activities. For example, a variety of methods are known in the art for generating phage display libraries and screening such libraries for antibodies possessing the desired binding characteristics. Such methods are reviewed, e.g., in Hoogenboom et al., Methods in Molecular Biology 178:1-37 (O'Brien et al., ed., Human Press, Totowa, N.J. (2001)) and further described, e.g., in McCafferty et al., Nature 348:552-554; Clackson et al., Nature 352: 624-628 (1991); Marks et al., J. Mol. Biol. 111'. 581-597 (1992); Marks and Bradbury, Methods in Molecular Biology 248:161-175 (Lo, ed., Human Press, Totowa, N.J., 2003); Sidhu et al., J. Mol. Biol. 338(2): 299- 310 (2004); Lee et al., J. Mol. Biol. 340(5): 1073-1093 (2004); Fellouse, Proc. Natl. Acad. Sci. USA 101(34): 12467-12472 (2004); and Lee et al., J. Immunol. Methods 284(1-2): 119- 132(2004).

[0192] In certain phage display methods, repertoires of VH and VL genes are separately cloned by polymerase chain reaction (PCR) and recombined randomly in phage libraries, which can then be screened for antigen-binding phage as described in Winter et al. , Ann. Rev. Immunol. , 12: 433-455 (1994). Phages typically display antibody fragments, either as scFv fragments or as Fab fragments. Libraries from immunized sources provide high-affinity antibodies to the immunogen without the requirement of constructing hybridomas. Alternatively, the naive repertoire can be cloned e.g., from human) to provide a single source of antibodies to a wide range of non- self and also self antigens without any immunization as described by Griffiths et al., EMBO J, 12: 725-734 (1993). Finally, naive libraries can also be made synthetically by cloning unrearranged V-gene segments from stem cells and using PCR primers containing random sequence to encode the highly variable CDR3 regions and to accomplish rearrangement in vitro, as described by Hoogenboom and Winter, J. Mol. Biol., 227: 381-388 (1992). Patent publications describing human antibody phage libraries include, for example: U.S. Pat. No. 5,750,373, and US Patent Publication Nos. 2005 / 0079574, 2005 / 0119455, 2005 / 0266000, 2007 / 0117126, 2007 / 0160598, 2007 / 0237764, 2007 / 0292936, and 2009 / 0002360.

[0193] The antibodies or antigen-binding fragments thereof can be prepared using phage display to screen libraries for antibodies specific to an MSLN ECD (e.g., an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2). The library can be a human scFv phage display library having a diversity of at least 1 x 109(such as at least about any of 1 x 109, 2.5 x 109, 5 x 109, 7.5 x 109, 1 x IO10, 2.5 x IO10, 5 x IO10, 7.5 x IO10, or 1 x 1011) unique human antibody fragments. In some embodiments, the library is a naive human library constructed from DNA extracted from human PMBCs and spleens from healthy donors, encompassing all human heavy and light chain subfamilies. In some embodiments, the library is a naive human library constructed from DNA extracted from PBMCs isolated from patients with various diseases, such as patients with autoimmune diseases, cancer patients, and patients with infectious diseases. In some embodiments, the library is a semi- synthetic human library, wherein heavy chain CDR3 is completely randomized, with all amino acids (with the exception of cysteine) equally likely to be present at any given position (see, e.g., Hoet, R.M. et al., Nat. Biotechnol. 23(3):344-348, 2005). In some embodiments, the heavy chain CDR3 of the semi-synthetic human library has a length from about 5 to about 24 (such as about any of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24) amino acids. In some embodiments, the library is a non-human phage display library.

[0194] Phage clones that bind to MSLN ECD with high affinity can be selected by iterative binding of phage to MSLN ECD, which is bound to a solid support (such as, for example, beads for solution panning or mammalian cells for cell panning), followed by removal of non-bound phage and by elution of specifically bound phage. In an example of solution panning, the MSLN can be biotinylated for immobilization to a solid support. The biotinylated MSLN is mixed with the phage library and a solid support, such as streptavidin-conjugated Dynabeads® M-280 (Thermo Fisher), and then MSLN-phage-bead complexes are isolated. The bound phage clones are then eluted and used to infect an appropriate host cell, such as E. coli XL 1 -Blue, for expression and purification. In an example of cell panning, cells loaded with human MSLN are mixed with the phage library, after which the cells are collected, and the bound clones are eluted and used to infect an appropriate host cell for expression and purification. The panning can be performed for multiple (such as about any of 2, 3, 4, 5, 6 or more) rounds with either solution panning, cell panning, or a combination of both, to enrich for phage clones binding specifically to MSLN ECD. Enriched phage clones can be tested for specific binding to MSLN ECD by any methods known in the art, including for example ELISA and FACS.Monoclonal Anti-MSLN Antibodies and Antibody Moieties

[0195] In some embodiments, an anti-MSLN construct of the present disclosure comprises a monoclonal anti-MSLN antibody or a monoclonal anti-MSLN antibody moiety. Monoclonal antibodies can be prepared, e.g., using hybridoma methods, such as those described by Kohler and Milstein, Nature, 256:495 (1975) and Sergeeva et al., Blood, 117(16): 4262-4272 (2011), using the phage display methods described herein and in the Examples below, or using recombinant DNA methods (see, e.g., US Patent No. 4,816,567).

[0196] In a hybridoma method, a hamster, mouse, or other appropriate host animal is typically immunized with an immunizing agent to elicit lymphocytes that produce or are capable of producing antibodies that will specifically bind to the immunizing agent. Alternatively, the lymphocytes can be immunized in vitro. The immunizing agent can include a polypeptide or a fusion protein of the protein of interest, or a complex comprising at least two molecules.Generally, peripheral blood lymphocytes (“PBLs”) are used if cells of human origin are desired, or spleen cells or lymph node cells are used if non-human mammalian sources are desired. The lymphocytes are then fused with an immortalized cell line using a suitable fusing agent, such as polyethylene glycol, to form a hybridoma cell. See, e.g., Goding, Monoclonal Antibodies: Principles and Practice (New York: Academic Press, 1986), pp. 59-103. Immortalized cell lines are usually transformed mammalian cells, particularly myeloma cells of rodent, bovine, and human origin. Usually, rat or mouse myeloma cell lines are employed. The hybridoma cells can be cultured in a suitable culture medium that preferably contains one or more substances that inhibit the growth or survival of the unfused, immortalized cells. For example, if the parental cells lack the enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT or HPRT), the culture medium for the hybridomas typically will include hypoxanthine, aminopterin, and thymidine (“HAT medium”), which prevents the growth of HGPRT-deficient cells.

[0197] In some embodiments, the immortalized cell lines fuse efficiently, support stable high- level expression of antibody by the selected antibody-producing cells, and are sensitive to a medium such as HAT medium. In some embodiments, the immortalized cell lines are murine myeloma lines, which can be obtained, for instance, from the Salk Institute Cell Distribution Center, San Diego, California and the American Type Culture Collection, Manassas, Virginia. Human myeloma and mouse-human heteromyeloma cell lines have also been described for the production of human monoclonal antibodies. Kozbor, J. Immunol., 133:3001 (1984); Brodeur etal. Monoclonal Antibody Production Techniques and Applications (Marcel Dekker, Inc. New York, 1987) pp. 51-63.

[0198] The culture medium in which the hybridoma cells are cultured can then be assayed for the presence of monoclonal antibodies directed against the polypeptide. The binding specificity of monoclonal antibodies produced by the hybridoma cells can be determined by immunoprecipitation or by an in vitro binding assay, such as RIA or ELISA. Such techniques and assays are known in the art. The binding affinity of the monoclonal antibody can, for example, be determined by the Scatchard analysis of Munson and Pollard, Anal. Biochem., 107:220 (1980).

[0199] After the desired hybridoma cells are identified, the clones can be sub-cloned by limiting dilution procedures and grown by standard methods. Goding, supra. Suitable culture media for this purpose include, for example, Dulbecco's Modified Eagle's Medium and RPML 1640 medium. Alternatively, the hybridoma cells can be grown in vivo as ascites in a mammal.

[0200] The monoclonal antibodies secreted by the sub clones can be isolated or purified from the culture medium or ascites fluid by conventional immunoglobulin purification procedures such as, for example, protein A-Sepharose, hydroxylapatite chromatography, gel electrophoresis, dialysis, or affinity chromatography.

[0201] In certain embodiments, the anti-MSLN antibody or antibody moiety is monovalent. Methods for preparing monovalent antibodies are known in the art. One exemplary method involves recombinant expression of immunoglobulin light chain and modified heavy chain. The heavy chain is truncated generally at any point in the Fc region so as to prevent heavy-chain crosslinking. Alternatively, the relevant cysteine residues are substituted with another amino acid residue or are deleted so as to prevent crosslinking.

[0202] In vitro methods are also suitable for preparing monovalent antibodies. Digestion of antibodies to produce fragments thereof, particularly Fab fragments, can be accomplished using any method known in the art.

[0203] Antibody variable domains with the desired binding specificities (antibody-antigen combining sites) can be fused to immunoglobulin constant-domain sequences. The fusion preferably is with an immunoglobulin heavy-chain constant domain, comprising at least part of the hinge, CH2, and CH3 regions. In some embodiments, the first heavy-chain constant region (CHI) containing the site necessary for light-chain binding is present in at least one of the fusions. DNAs encoding the immunoglobulin heavy-chain fusions and, if desired, theimmunoglobulin light chain, are inserted into separate expression vectors, and are co-transfected into a suitable host organism. For further details of generating bispecific antibodies, see, for example, Suresh et al., Methods in Enzymology, 121: 210 (1986).

[0204] Monoclonal antibodies can also be made by recombinant DNA methods, such as those described in U.S. Patent No. 4,816,567. DNA encoding the monoclonal anti-MSLN antibodies can be readily isolated and sequenced using conventional procedures (e.g., by using oligonucleotide probes that are capable of binding specifically to genes encoding the heavy and light chains of murine antibodies). Hybridoma cells as described above or MSLN-specific phage clones can serve as a source of such DNA. Once isolated, the DNA can be placed into expression vectors, which are then transfected into host cells such as simian COS cells, Chinese hamster ovary (CHO) cells, or myeloma cells that do not otherwise produce immunoglobulin protein, to obtain the synthesis of monoclonal antibodies in the recombinant host cells. The DNA also can be modified, for example, by substituting the coding sequence for human heavy- and light-chain constant domains and / or framework regions in place of the homologous nonhuman sequences (U.S. Patent No. 4,816,567; Morrison et al., supra) or by covalently joining to the immunoglobulin coding sequence all or part of the coding sequence for a nonimmunoglobulin polypeptide. Such a non-immunoglobulin polypeptide can be substituted for the constant domains of an anti-MSLN antibody or can be substituted for the variable domains of one antigen-combining site of an anti-MSLN antibody to create a chimeric bivalent antibody.Human and Humanized Anti-MSLN Antibodies and Antibody Moieties, and Preparation Thereof

[0205] The anti-MSLN antibodies or anti-MSLN antibody moieties can be humanized antibodies or human antibodies. Humanized forms of non-human (e.g., murine) antibodies are chimeric immunoglobulins, immunoglobulin chains, or fragments thereof (such as Fv, Fab, Fab’, F(ab’)2, scFv, or other antigen-binding subsequences of antibodies) that typically contain minimal sequence derived from non-human immunoglobulin. Humanized antibodies include human immunoglobulins (recipient antibody) in which residues from a CDR of the recipient are replaced by residues from a CDR of a non-human species (donor antibody) such as mouse, rat, or rabbit having the desired specificity, affinity, and capacity. In some instances, Fv framework residues of the human immunoglobulin are replaced by corresponding non-human residues. Humanized antibodies can also comprise residues that are found neither in the recipient antibody nor in the imported CDR or framework sequences. In general, the humanized antibody cancomprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin, and all or substantially all of the FR regions are those of a human immunoglobulin consensus sequence. In some embodiments, the humanized antibody will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. See, e.g., Jones et al., Nature, 321: 522-525 (1986); Riechmann et al., Nature, 332: 323-329 (1988); Presta, Curr. Op. Struct. Biol., 2:593-596 (1992).

[0206] Generally, a humanized antibody has one or more amino acid residues introduced into it from a source that is non-human. These non-human amino acid residues are often referred to as “import” residues, which are typically taken from an “import” variable domain. According to some embodiments, humanization can be essentially performed following the method of Winter and co-workers (Jones et al., Nature, 321: 522-525 (1986); Riechmann et al., Nature, 332: 323- 327 (1988); Verhoeyen et al., Science, 239: 1534-1536 (1988)), by substituting rodent CDRs or CDR sequences for the corresponding sequences of a human antibody. Accordingly, such “humanized” antibodies are antibodies (U.S. Patent No. 4,816,567), wherein substantially less than an intact human variable domain has been substituted by the corresponding sequence from a non-human species. In practice, humanized antibodies are typically human antibodies in which some CDR residues and possibly some FR residues are substituted by residues from analogous sites in rodent antibodies.

[0207] As an alternative to humanization, human antibodies can be generated. For example, it is now possible to produce transgenic animals (e.g., mice) that are capable, upon immunization, of producing a full repertoire of human antibodies in the absence of endogenous immunoglobulin production. For example, it has been described that the homozygous deletion of the antibody heavy-chain joining region (JH) gene in chimeric and germ-line mutant mice results in complete inhibition of endogenous antibody production. Transfer of the human germ-line immunoglobulin gene array into such germ-line mutant mice will result in the production of human antibodies upon antigen challenge. See, e.g., Jakobovits et al., PNAS USA, 90:2551 (1993); Jakobovits et al., Nature, 362:255-258 (1993); Bruggemann et al., Year in Immunol., 7:33 (1993); U.S. Patent Nos. 5,545,806, 5,569,825, 5,591,669; 5,545,807; and WO 97 / 17852. Alternatively, human antibodies can be made by introducing human immunoglobulin loci into transgenic animals, e.g., mice in which the endogenous immunoglobulin genes have been partially or completely inactivated. Upon challenge, human antibody production is observed thatclosely resembles that seen in humans in all respects, including gene rearrangement, assembly, and antibody repertoire. This approach is described, for example, in U.S. Patent Nos. 5,545,807; 5,545,806; 5,569,825; 5,625,126; 5,633,425; and 5,661,016, and Marks et al., Bio / Technology, 10: 779-783 (1992); Lonberg et al., Nature, 368: 856-859 (1994); Morrison, Nature, 368: 812- 813 (1994); Fishwild et al., Nature Biotechnology, 14: 845-851 (1996); Neuberger, Nature Biotechnology, 14: 826 (1996); Lonberg and Huszar, Intern. Rev. Immunol., 13: 65-93 (1995).

[0208] Human antibodies may also be generated by in vitro activated B cells (see U.S. Patents 5,567,610 and 5,229,275) or by using various techniques known in the art, including phage display libraries. Hoogenboom and Winter, J. Mol. Biol., 227:381 (1991); Marks et al., J. Mol. Biol., 222:581 (1991). The techniques of Cole et al. and Boerner et al. are also available for the preparation of human monoclonal antibodies. Cole et al., Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, p. 77 (1985) and Boerner et al., J. Immunol., 147(1): 86-95 (1991).Full-Length Anti-MSLN Antibodies

[0209] In some embodiments, the anti-MSLN construct provided herein is or comprises a full- length antibody, e.g., a full-length anti-MSLN antibody moiety or a full-length antibody comprising an anti-MSLN antibody moiety, also referred to herein as a “full-length anti-MSLN antibody.” In some embodiments, the full-length anti-MSLN antibody is a monoclonal antibody, as described in further detail elsewhere herein.

[0210] In some embodiments, the full-length anti-MSLN antibody comprises an Fc sequence from an immunoglobulin, e.g., a human immunoglobulin such as IgA, IgD, IgE, IgG, or IgM. In some embodiments, the full-length anti-MSLN antibody comprises an Fc sequence of IgG, e.g., a human IgG, such as any of IgGl, IgG2, IgG3, or IgG4. In some embodiments, the full-length anti-MSLN antibody comprises an Fc sequence of a rabbit, rat, or mouse immunoglobulin. In some embodiments, the full-length anti-MSLN antibody comprises an Fc sequence of a nonhuman primate (e.g., a rhesus monkey or cynomolgus monkey). In some embodiments, the full- length anti-MSLN antibody comprises an Fc sequence that has been altered or otherwise changed so that it has enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) function and / or enhanced complement dependent cytotoxicity (CDC) effector function, as described in further detail elsewhere herein.

[0211] Thus, for example, in some embodiments, there is provided a full-length anti-MSLN antibody comprising a) any one of the anti-MSLN antibody moieties described herein thatspecifically binds to MSLN ECD, and b) an Fc region. In some embodiments, the MSLN ECD comprises the amino acid sequence of SEQ ID NO: 2. In some embodiments, the Fc region comprises an IgGl Fc sequence. In some embodiments, the Fc region comprises a human IgGl Fc sequence. In some embodiments, the Fc region comprises a mouse IgGl Fc sequence.

[0212] In some embodiments, there is provided a full-length anti-MSEN antibody comprising any one of the anti-MSEN antibody moieties provided herein. In some embodiments, the full- length anti-MSEN antibody comprises the anti-MSEN antibody moiety of Clone A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, or A46. In some embodiments, there is provided a full-length anti-MSEN antibody comprising a) the anti-MSLN antibody moiety of Clone A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, or A46, and b) an Fc region. In some embodiments, the Fc region comprises an IgGl Fc sequence. In some embodiments, the Fc region comprises a human IgGl Fc sequence. In some embodiments, the Fc region comprises a mouse IgGl Fc sequence.

[0213] In some embodiments, the full-length anti-MSEN antibody binds to MSEN with a Kd between about 0.1 pM to about 500 nM (such as about any of 0.1 pM, 1.0 pM, 10 pM, 50 pM, 100 pM, 500 pM, 1 nM, 10 nM, 50 nM, 100 nM, or 500 nM, including any ranges between these values). In some embodiments, the full-length anti-MSEN antibody binds to MSEN with a Kd between about 1 pM to about 250 pM (such as about any of 1, 10, 25, 50, 75, 100, 150, 200, or 250 pM, including any ranges between these values).Multispecific Anti-MSLN Molecules

[0214] The anti-MSEN constructs in some embodiments comprise a multispecific anti-MSEN molecule comprising an anti-MSEN antibody moiety and a second binding moiety (such as a second antigen-binding moiety). In some embodiments, the multispecific anti-MSLN molecule comprises an anti-MSLN antibody moiety and a second antigen-binding moiety.

[0215] Multispecific molecules are molecules that have binding specificities for at least two different antigens or epitopes (e.g., bispecific antibodies have binding specificities for two antigens or epitopes). Multispecific molecules with more than two valencies and / or specificities are also contemplated. For example, trispecific antibodies can be prepared. Tutt et al. J. Immunol. 147: 60 (1991). It is to be appreciated that one of skill in the art could select appropriate features of individual multispecific molecules described herein to combine with one another to form a multispecific anti-MSLN molecule of the present application.

[0216] Thus, for example, in some embodiments, there is provided a multispecific (e.g., bispecific) anti-MSLN molecule comprising: a) a first binding moiety (such as a first antigenbinding moiety) comprising one of the anti-MSLN antibody moieties described herein that specifically binds to an MSLN ECD (e.g., a first anti-MSLN antibody moiety), and b) a second binding moiety (such as a second antigen-binding moiety). In some embodiments, the first binding moiety is a first scFv and the second binding moiety is a second scFv. In some embodiments, the second binding moiety specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2 (e.g., a second anti-MSLN antibody moiety). In some embodiments, the second anti-MSLN antibody moiety is identical to the first anti-MSLN antibody moiety. In some embodiments, the second anti-MSLN antibody moiety is different from the first anti-MSLN antibody moiety. In some embodiments, the second anti-MSLN antibody moiety specifically binds to a different region of an MSLN ECD (e.g., SEQ ID NO: 2) than the region of the MSLN ECD that is specifically bound by the first anti-MSLN antibody moiety. In some embodiments, the second anti-MSLN antibody moiety specifically binds to the same region of an MSLN ECD (e.g., SEQ ID NO: 2) as the region of the MSLN ECD that is specifically bound by the first anti-MSLN antibody moiety, but specifically binds an epitope that is non-overlapping with the epitope specifically bound by the first anti-MSLN antibody moiety. In some embodiments, the second binding moiety specifically binds to an antigen that is not MSLN (e.g., a non-MSLN-ECD target). In some embodiments, the second binding moiety specifically binds to an antigen on the surface of a cell, such as a cytotoxic cell (e.g., a cellsurface antigen). In some embodiments, the second binding moiety specifically binds to an antigen on the surface of a lymphocyte, such as a T cell, an NK cell, a neutrophil, a monocyte, a macrophage, or a dendritic cell. In some embodiments, the second binding moiety specifically binds to an effector T cell, such as a cytotoxic T cell (also known as cytotoxic T lymphocyte (CTL) or T killer cell). In some embodiments, the second binding moiety specifically binds to an antigenic peptide / MHC class I complex.

[0217] In some embodiments, there is provided a multispecific anti-MSLN molecule comprising a) an anti-MSLN antibody moiety, and b) a second antigen-binding moiety that binds specifically to CD3. In some embodiments, the second antigen -binding moiety specifically binds to CD3s. In some embodiments, the second antigen-binding moiety specifically binds to an agonistic epitope of CD3s. The term “agonistic epitope”, as used herein, means (a) an epitope that, upon binding of the multispecific molecule, optionally upon binding of severalmultispecific molecules on the same cell, allows said multispecific molecules to activate T cell receptor signaling and induce T cell activation, and / or (b) an epitope that is solely composed of amino acid residues of the epsilon chain of CD3 and is accessible for binding by the multispecific molecule, when presented in its natural context on T cells (i.e. surrounded by the TCR, the CD3y chain, etc.), and / or (c) an epitope that, upon binding of the multispecific molecule, does not lead to stabilization of the spatial position of CD3s relative to CD3y.

[0218] In some embodiments, there is provided a multispecific anti-MSLN molecule comprising a) an anti-MSLN antibody moiety, and b) a second antigen-binding moiety that binds specifically to an antigen on the surface of an effector cell, including for example CD3y, CD35, CD3s, CD3 , CD28, CD16a, CD56, CD68, and GDS2D.

[0219] In some embodiments, there is provided a multispecific anti-MSLN molecule comprising a) an anti-MSLN antibody moiety, and b) a second antigen-binding moiety that binds specifically to a component of the complement system, such as Clq. Clq is a subunit of the Cl enzyme complex that activates the serum complement system.

[0220] In some embodiments, the second antigen-binding moiety specifically binds to an Fc receptor. In some embodiments, the second antigen-binding moiety specifically binds to an Fey receptor (FcyR). The FcyR may be an FcyRIII present on the surface of natural killer (NK) cells or one of FcyRI, FcyRIIA, FcyRIIBI, FcyRIIB2, and FcyRIIIB present on the surface of macrophages, monocytes, neutrophils and / or dendritic cells. In some embodiments, the second antigen-binding moiety is an Fc region or functional fragment thereof. A “functional fragment” as used in this context refers to a fragment of an antibody Fc region that is still capable of binding to an FcR, in particular to an FcyR, with sufficient specificity and affinity to allow an FcyR bearing effector cell, in particular a macrophage, a monocyte, a neutrophil and / or a dendritic cell, to kill the target cell by cytotoxic lysis or phagocytosis. A functional Fc fragment is capable of competitively inhibiting the binding of the original, full-length Fc portion to an FcR such as the activating FcyRI. In some embodiments, a functional Fc fragment retains at least 30%, 40%, 50%, 60%, 70%, 80%, 90% or 95% of its affinity to an activating FcyR. In some embodiments, the Fc region or functional fragment thereof is an enhanced Fc region or functional fragment thereof. The term “enhanced Fc region”, as used herein, refers to an Fc region that is modified to enhance Fc receptor-mediated effector- functions, in particular ADCC, CDC, and antibody-mediated phagocytosis. This can be achieved as known in the art, for example by altering the Fc region in a way that leads to an increased affinity for an activatingreceptor (e.g., FcyRIIIA (CD16A) expressed on NK cells) and / or a decreased binding to an inhibitory receptor (e.g., FcyRIIBl / B2 (CD32B)). In yet other embodiments, the second antigenbinding moiety is an antibody or antigen-binding fragment thereof that specifically binds to an FcR, in particular to an FcyR, with sufficient specificity and affinity to allow an FcyR bearing effector cell, in particular a macrophage, a monocyte, a neutrophil and / or a dendritic cell, to kill the target cell by cytotoxic lysis or phagocytosis.

[0221] In some embodiments, the multispecific anti-MSLN molecule allows killing of MSLN- presenting target cells and / or can effectively redirect CTLs to lyse MSLN-presenting target cells. In some embodiments, the multispecific (e.g., bispecific) anti-MSLN molecule of the present application shows an in vitro EC50 ranging from 10 to 500 ng / mL and is able to induce redirected lysis of about 50% of the target cells through CTLs at a ratio of CTLs to target cells of from about 1:1 to about 50:1 (such as from about 1:1 to about 15:1, or from about 2:1 to about 10:1).

[0222] In some embodiments, the multispecific (e.g., bispecific) anti-MSLN molecule is capable of cross-linking a stimulated or unstimulated CTL and the target cell in such a way that the target cell is lysed. This offers the advantage that no generation of target- specific T cell clones or common antigen presentation by dendritic cells is required for the multispecific anti- MSLN molecule to exert its desired activity. In some embodiments, the multispecific anti- MSLN molecule of the present application is capable of redirecting CTLs to lyse the target cells in the absence of other activating signals. In some embodiments, the second antigen-binding moiety of the multispecific anti-MSLN molecule specifically binds to CD3 (e.g., specifically binds to CD3s), and signaling through CD28 and / or IL-2 is not required for redirecting CTLs to lyse the target cells.

[0223] Methods for measuring the preference of the multispecific anti-MSLN molecule to simultaneously bind to two antigens (e.g., antigens on two different cells) are within the normal capabilities of a person skilled in the art. For example, when the second binding moiety specifically binds to CD3, the multispecific anti-MSLN molecule may be contacted with a mixture of CD3+ / MSLN" cells and CD37MSLN+cells. The number of multispecific anti-MSLN molecule-positive single cells and the number of cells cross-linked by multispecific anti-MSLN molecules may then be assessed by microscopy or FACS as known in the art.

[0224] For example, in some embodiments, there is provided a multispecific anti-MSLN molecule comprising: a) a first antigen-binding moiety comprising any one of the anti-MSLNantibody moieties described herein that specifically binds to an MSLN ECD (e.g., an anti-MSLN antibody moiety, such as first anti-MSLN antibody moiety), and b) a second antigen-binding moiety. In some embodiments, the MSLN ECD comprises the amino acid sequence of SEQ ID NO: 2. In some embodiments, the anti-MSLN antibody moiety is human, humanized, or semisynthetic. In some embodiments, the second antigen-binding moiety is an antibody moiety. In some embodiments, the second antigen-binding moiety is a human, humanized, or semisynthetic antibody moiety. In some embodiments, the first antigen-binding moiety is a first scFv and the second antigen-binding moiety is a second scFv. In some embodiments, the second antigen-binding moiety specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2 (e.g., a second anti-MSLN antibody moiety). In some embodiments, the second anti-MSLN antibody moiety is identical to the first anti-MSLN antibody moiety. In some embodiments, the second anti-MSLN antibody moiety is different from the first anti- MSLN antibody moiety. In some embodiments, the second anti-MSLN antibody moiety specifically binds to a different region of an MSLN ECD (e.g., SEQ ID NO: 2) than the region of the MSLN ECD that is specifically bound by the first anti-MSLN antibody moiety. In some embodiments, the second anti-MSLN antibody moiety specifically binds to the same region of an MSLN ECD (e.g., SEQ ID NO: 2) as the region of the MSLN ECD that is specifically bound by the first anti-MSLN antibody moiety, but specifically binds an epitope that is nonoverlapping with the epitope specifically bound by the first anti-MSLN antibody moiety. In some embodiments, the second antigen-binding moiety specifically binds to an antigen that is not MSLN (e.g., a non-MSLN-ECD target). In some embodiments, the second antigen-binding moiety specifically binds to an antigen on the surface of a cell (e.g., a cell-surface antigen), such as an MSLN-presenting cell. In some embodiments, the second antigen-binding moiety specifically binds to an antigen on the surface of a cell that does not express an MSLN. In some embodiments, the second antigen-binding moiety specifically binds to an antigen on the surface of a cytotoxic cell. In some embodiments, the second antigen-binding moiety specifically binds to an antigen on the surface of a lymphocyte, such as a T cell, an NK cell, a neutrophil, a monocyte, a macrophage, or a dendritic cell. In some embodiments, the second antigen-binding moiety specifically binds to an antigen on the surface of an effector T cell, such as a cytotoxic T cell. In some embodiments, the second antigen-binding moiety specifically binds to an antigen on the surface of an effector cell, including for example CD3y, CD35, CD3s, CD3^, CD28, CD16a, CD56, CD68, and GDS2D. In some embodiments, the second binding moietyspecifically binds to an antigenic peptide / MHC class I complex. In some embodiments, the multispecific anti-MSLN molecule further comprises at least one (such as at least about any of 2, 3, 4, 5, or more) additional antigen-binding moieties.

[0225] In some embodiments, there is provided a multispecific anti-MSLN molecule comprising: a) a first antigen-binding moiety comprising any one of the anti-MSLN antibody moieties described herein that specifically binds to an MSLN ECD (e.g., an anti-MSLN antibody moiety, such as first anti-MSLN antibody moiety), and b) a second antigen-binding moiety. In some embodiments, the second antigen-binding moiety specifically binds CD3. In some embodiments, the second antigen-binding moiety specifically binds CD3e. In some embodiments, the second antigen-binding moiety is a CD3e antibody that specifically binds CD3e. For additional description of CD3e antibodies, see, for example, US 10968276, the contents of which are herein incorporated by reference in its entirety.

[0226] In some embodiments, the second antigen-binding moiety comprises a full-length antibody, a Fab, a Fab’, a F(ab’)2, an Fv, or an scFv.

[0227] In some embodiments, the multispecific anti-MSEN construct is, for example, a bispecific antibody, a diabody (Db), a single-chain diabody (scDb), a tandem scDb (TandAb), a linear dimeric scDb (ED-scDb), a circular dimeric scDb (CD-scDb), a di-diabody, a tandem scFv, a tandem di-scFv, a tandem tri-scFv, a tri(a)body, a bispecific Fab2, a di-miniantibody, a tetrabody, an scFv-Fc-scFv fusion, a dual-affinity retargeting (DART) antibody, a dual variable domain (DVD) antibody, an IgG-scFab, an scFab-ds-scFv, an Fv2-Fc, an IgG-scFv fusion, a dock and lock (DNE) antibody, a knob-into-hole (KiH) antibody (bispecific IgG prepared by the KiH technology), a DuoBody (bispecific IgG prepared by the DuoBody technology), a heteromultimeric antibody, or a heteroconjugate antibody. In some embodiments, the multispecific anti-MSEN molecule is a tandem scFv (e.g., a tandem di-scFv). It is to be appreciated that one of ordinary skill in the art could select appropriate features of various multispecific constructs known in the art and combine them with one another to form a further multispecific anti-MSEN construct within the scope of this disclosure.

[0228] Suitable methods for making multispecific constructs (e.g., bispecific antibodies) are well known in the art. For example, the production of bispecific antibodies can be based on the co-expression of two immunoglobulin heavy-chain / light-chain pairs, where the two pairs each have different specificities, and upon association result in a heterodimeric antibody (see, e.g., Milstein and Cuello, Nature, 305: 537-539 (1983); WO 93 / 08829, and Traunecker et al., EMBOJ. 10: 3655 (1991)). Because of the random assortment of immunoglobulin heavy and light chains, these hybridomas (quadromas) produce a potential mixture of ten different antibody molecules, of which only one has the correct bispecific structure. The purification of the correct molecule is usually accomplished by affinity chromatography steps. Similar procedures are disclosed in WO 93 / 08829 and in Traunecker et al., EMBO, 10: 3655-3659 (1991). Alternatively, the combining of heavy and light chains can be directed by taking advantage of species-restricted pairing (see, e.g., Lindhofer et al., J. Immunol., 155:219-225 (1995)) and the pairing of heavy chains can be directed by use of “knob-into hole” engineering of CH3 domains (see, e.g., U.S. Pat. No. 5,731,168; Ridgway et al., Protein Eng., 9(7):617-621 (1996)). Multispecific antibodies may also be made by engineering electrostatic steering effects for making antibody Fc-heterodimeric molecules (see, e.g., WO 2009 / 089004A1). In yet another method, stable bispecific antibodies can be generated by controlled Fab-arm exchange, where two parental antibodies having distinct antigen specificity and matched point mutations in the CH3 domains are mixed in reducing condition to allow for separation, reassembly, and reoxidation to form highly pure bispecific antibodies. Labrigin et al., Proc. Natl. Acad. Sci., 110(13):5145-5150 (2013). Such antibodies, comprising a mixture of heavy-chain / light-chain pairs, are also referred to herein as “heteromultimeric antibodies.”

[0229] Antibodies or antigen-binding fragments thereof having different specificities can also be chemically cross-linked to generate multispecific heteroconjugate antibodies. For example, two F(ab’)2 molecules, each having specificity for a different antigen, can be chemically linked. Pullarkat et al., Trends Biotechnol., 48:9-21 (1999). Such antibodies have, for example, been proposed to target immune-system cells to unwanted cells (U.S. Patent No. 4,676,980), and for treatment of HIV infection (WO 91 / 00360; WO 18 / 125813). It is contemplated that the antibodies can be prepared in vitro using known methods in synthetic protein chemistry, including those involving crosslinking agents. For example, immunotoxins can be constructed using a disulfide-exchange reaction or by forming a thioether bond. Examples of suitable reagents for this purpose include iminothiolate and methyl-4-mercaptobutyrimidate and those disclosed, for example, in U.S. Patent No. 4,676,980.

[0230] In some embodiments, multispecific anti-MSLN constructs can be prepared using recombinant DNA techniques. For example, a bispecific antibody can be engineered by fusing two scFvs, such as by fusing them through a peptide linker, resulting in a tandem scFv (such as a tandem di-scFv). The terms “anti-MSLN tandem di-scFv” and “bispecific anti-MSLN antibody”are used interchangeably herein. In some embodiments, the tandem scFv comprises an anti-CD3 scFv to an scFv comprising an anti-MSLN-binding moiety described herein, resulting in the redirection of T cells to target cells that express (such as overexpress) the target. Additional details regarding the construction and expression of tandem scFvs are provided in, e.g., Mack et al., Proc. Natl. Acad. Sci., 92:7021-7025 (1995); Brischwein et al., Mol. Immunol., 43(8):1129- 1143 (2006). Additional details regarding tandem scFvs of the present disclosure are provided elsewhere herein.

[0231] By shortening the length of a peptide linker between two variable domains, the variable domains can be prevented from self-assembling and forced to pair with domains on a second polypeptide, resulting in a compact bispecific antibody called a diabody (Db). Holliger et al., Proc. Natl. Acad. Sci., 90:6444-6448 (1993). The two polypeptides of a Db each comprise a VH connected to a VL by a linker which is too short to allow pairing between the two domains on the same chain. Accordingly, the VH and VL of one polypeptide are forced to pair with the complementary VL and VH of another polypeptide, thereby forming two antigen-binding sites. In a modification of this format, the two polypeptides are linked by another peptide linker, resulting in a single chain diabody (scDb). In yet another modification of the Db format, dual-affinity retargeting (DART) bispecific antibodies can be generated by introducing a disulfide linkage between cysteine residues at the C-terminus of each polypeptide, optionally including domains prior to the C-terminal cysteine residues that drive assembly of the desired heterodimeric structure. Veri et al., Arthritis Rheum., 62(7): 1933- 1943 (2010). Dual-variable-domain immunoglobulins (DVD-Ig™), in which the target-binding variable domains of two monoclonal antibodies are combined via naturally occurring linkers to yield a tetravalent, bispecific antibody, are also known in the art. Gu and Ghayur, Methods Enzymol., 502:25-41 (2012). In yet another format, Dock and Lock (DNL), bispecific antibodies are prepared by taking advantage of the dimerization of a peptide (DDD2) derived from the regulatory subunit of human cAMP- dependent protein kinase (PKA) with a peptide (AD2) derived from the anchoring domains of human A kinase anchor proteins (AKAPs). Rossi et al., Proc. Natl. Acad. Sci., 103:6841-6846 (2006).

[0232] Various techniques for making and isolating bispecific antibody fragments directly from recombinant cell culture have also been described. For example, bispecific antibodies have been produced using leucine zippers. Kostelny et al., J. Immunol., 148(5): 1547- 1553 (1992). This method can also be utilized for the production of antibody homodimers.Tandem scFv Constructs

[0233] In some embodiments, the multispecific anti-MSLN construct is a tandem scFv construct (“anti-MSLN tandem scFv”) comprising a first scFv that comprises an anti-MSLN antibody moiety (such as described herein, e.g., a first anti-MSLN antibody moiety) and a second scFv that binds to a second target (e.g., a second target antigen, such as a cell-surface antigen or an antigenic peptide / MHC class I complex). In some embodiments, the tandem scFv is a di-scFv (comprising two scFvs) or a tandem tri-scFv (comprising three scFvs). In some embodiments, the anti-MSLN tandem scFv further comprises at least 3, 4, 5, 6, 7, 8, 9, 10, or more scFvs. In some embodiments, the first scFv specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2. In some embodiments, the second scFv comprises a second anti-MSLN antibody moiety that specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2. In some embodiments, the second scFv is identical to the first scFv. In some embodiments, the second scFv is different from the first scFv. In some embodiments, the second scFv specifically binds to a different region of an MSLN ECD e.g., SEQ ID NO: 2) than the region of the MSLN ECD that is specifically bound by the first scFv. In some embodiments, the second scFv specifically binds to the same region of an MSLN ECD (e.g., SEQ ID NO: 2) as the region of the MSLN ECD that is specifically bound by the first scFv, but specifically binds an epitope that is non-overlapping with the epitope specifically bound by the first scFv. In some embodiments, the second scFv specifically binds to another antigen (i.e., an antigen other than MSLN). In some embodiments, the second scFv binds to a target antigen other than an MSLN ECD. In some embodiments, the second scFv specifically binds to an antigen on the surface of a cell (e.g., a cell-surface antigen), such as a cell that expresses an MSLN (e.g., a cancer cell). In some embodiments, the second scFv specifically binds to an antigen on the surface of a cell that does not express an MSLN. In some embodiments, the second scFv specifically binds to an antigen on the surface of a cytotoxic cell. In some embodiments, the second scFv specifically binds to an antigen on the surface of a lymphocyte, such as a T cell, an NK cell, a neutrophil, a monocyte, a macrophage, or a dendritic cell. In some embodiments, the second scFv specifically binds to an antigen on the surface of an effector T cell, such as a cytotoxic T cell. In some embodiments, the second scFv specifically binds to an antigen on the surface of an effector cell, including for example CD3y, CD35, CD3s, CD3(^, CD28, CD16a, CD56, CD68, and GDS2D. In some embodiments, the second scFvspecifically binds to an antigenic peptide / MHC class I complex. In some embodiments, the first scFv and / or the second scFv is human, humanized, or semi-synthetic.

[0234] In some embodiments, there is provided a tandem scFv multispecific (e.g., bispecific) anti-MSLN antibody comprising: a) a first scFv comprising an anti-MSLN antibody moiety (such as described herein, e.g., a first anti-MSLN antibody moiety) that specifically binds to a an MSLN ECD, and b) a second scFv. In some embodiments, the first scFv specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2. In some embodiments, the second scFv comprises a second anti-MSLN antibody moiety that specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2. In some embodiments, the second scFv is identical to the first scFv. In some embodiments, the second scFv is different from the first scFv. In some embodiments, the second scFv specifically binds to a different region of an MSLN ECD (e.g., SEQ ID NO: 2) than the region of the MSLN ECD that is specifically bound by the first scFv. In some embodiments, the second scFv specifically binds to the same region of an MSLN ECD (e.g., SEQ ID NO: 2) as the region of the MSLN ECD that is specifically bound by the first scFv, but specifically binds an epitope that is non-overlapping with the epitope specifically bound by the first scFv. In some embodiments, the second scFv specifically binds to another antigen (i.e., an antigen other than MSLN). In some embodiments, the second scFv binds to a target antigen other than an MSLN ECD. In some embodiments, the second scFv specifically binds to an antigen on the surface of a cell (e.g., a cell-surface antigen), such as a cell that expresses an MSLN (e.g., a cancer cell), e.g., an MSLN-presenting cell. In some embodiments, the second scFv specifically binds to an antigen on the surface of a cell that does not express MSLN. In some embodiments, the second scFv specifically binds to an antigen on the surface of a cytotoxic cell. In some embodiments, the second scFv specifically binds to an antigen on the surface of a lymphocyte, such as a T cell, an NK cell, a neutrophil, a monocyte, a macrophage, or a dendritic cell. In some embodiments, the second scFv specifically binds to an antigen on the surface of an effector T cell, such as a cytotoxic T cell. In some embodiments, the second scFv specifically binds to an antigen on the surface of an effector cell, including for example CD3y, CD35, CD3s, CD3^, CD28, CD16a, CD56, CD68, and GDS2D. In some embodiments, the second scFv specifically binds to an antigenic peptide / MHC complex. In some embodiments, the first scFv is human, humanized, or semi- synthetic. In some embodiments, the second scFv is human, humanized, or semi-synthetic. In some embodiments, both the first scFv and the second scFv are human, humanized, or semi- synthetic. In some embodiments, thetandem scFv multispecific anti-MSLN antibody further comprises at least one (such as at least about any of 2, 3, 4, 5, or more) additional scFv. In some embodiments, the anti-MSLN antibody moiety cross-reacts with at least one (such as at least any of 2, 3, 4, 5, or 6) variant of the MSLN ECD having one or more amino acid substitutions (such as a conservative amino acid substitution).

[0235] In some embodiments, there is provided a tandem scFv multispecific (e.g., bispecific) anti-MSLN antibody comprising: a) a first scFv comprising an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties described herein, that specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2, and b) a second scEv.

[0236] In some embodiments, there is provided a tandem scEv multispecific (e.g., bispecific) anti-MSLN antibody comprising: a) a first scFv comprising an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties described herein, that specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2, and b) a second scFv, wherein the tandem scFv multispecific anti-MSLN antibody is a tandem di-scFv or a tandem tri- scFv. In some embodiments, the tandem scFv multispecific anti-MSLN antibody is a tandem di- scFv. In some embodiments, the tandem scFv multispecific anti-MSLN antibody is a bispecific T-cell engager.

[0237] For example, in some embodiments, there is provided a tandem di-scFv bispecific anti- MSLN antibody comprising: a) a first scFv comprising an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties described herein, that specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2, and b) a second scFv that specifically binds to an antigen on the surface of a T cell (e.g., a cell-surface antigen). In some embodiments, the second scFv specifically binds to an antigen on the surface of an effector T cell, such as a cytotoxic T cell. In some embodiments, the second scFv specifically binds to an antigen selected, for example, from the group consisting of CD3, CD3y, CD35, CD3s, CD3^, CD28, 0X40, GITR, CD 137, CD27, CD40L, and HVEM. In some embodiments, the second scFv specifically binds to an agonistic epitope on an antigen on the surface of a T cell, wherein the binding of the second scFv to the antigen enhances T cell activation. In some embodiments, the first scFv is human, humanized, or semi-synthetic. In some embodiments, the second scFv is human, humanized, or semi- synthetic. In some embodiments, both the first scFv and the second scFv are human, humanized, or semi-synthetic.

[0238] In some embodiments, there is provided a tandem di-scFv bispecific anti-MSLN antibody comprising: a) a first scFv comprising an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties described herein, that specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2, and b) a second scFv that specifically binds to an antigenic peptide / MHC class I complex. In some embodiments, the first scFv is human, humanized, or semi- synthetic. In some embodiments, the second scFv is human, humanized, or semi- synthetic. In some embodiments, both the first scFv and the second scFv are human, humanized, or semi- synthetic.

[0239] In some embodiments, there is provided a tandem di-scFv bispecific anti-MSLN antibody comprising: a) a first scFv comprising an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties described herein, that specifically binds to an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2, and b) a second scFv that specifically binds to CD3s. In some embodiments, the first scFv is fused to the second scFv through linkage with a peptide linker. In some embodiments, the peptide linker is between about 5 to about 20 (such as about any of 5, 10, 15, or 20, including any ranges between these values) amino acids in length. In some embodiments, the peptide linker comprises (and in some embodiments consists of) the amino acid sequence SRGGGGSGGGGSGGGGSLEMA (SEQ ID NO: 215). In some embodiments, the first scFv is human, humanized, or semi- synthetic. In some embodiments, the second scFv is human, humanized, or semi-synthetic. In some embodiments, both the first scFv and the second scFv are human, humanized, or semi- synthetic.

[0240] In some embodiments, the tandem di-scFv bispecific anti-MSLN antibody binds to MSLN with a Kd between about 0.1 pM to about 500 nM (such as about any of 0.1 pM, 1.0 pM, 10 pM, 50 pM, 100 pM, 500 pM, 1 nM, 10 nM, 50 nM, 100 nM, or 500 nM, including any ranges between these values). In some embodiments, the tandem di-scFv bispecific anti-MSLN antibody binds to MSLN with a Kd between about 1 nM to about 500 nM (such as about any of 1, 10, 25, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, or 500 nM, including any ranges between these values).

[0241] In some embodiments, the multispecific anti-MSLN molecule (such as di-scFv) comprises an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties described herein. In some embodiments, multispecific anti-MSLN molecule comprises the anti- MSLN antibody moiety of Clone A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, or A46.Chimeric Receptors and Effector Cells

[0242] In some aspects, the anti-MSLN construct provided herein is a chimeric receptor comprising an anti-MSLN antibody moiety (such as any one of the anti-MSLN antibody moieties described in the “Anti-MSLN Antibody Moieties” section). As described in further detail elsewhere herein, the present disclosure also provides chimeric receptor effector cells (e.g., T cells) that comprise, express, or are associated with an anti-MSLN chimeric receptor. Such effector cells are also referred to herein as “anti-MSLN effector cells”. Anti-MSLN chimeric receptors and / or effector cells within the scope of the present application include, without limitation, e.g., anti-MSLN CARs, anti-MSLN caTCRs, anti-MSLN CSRs, and others, as described herein below.Chimeric Antigen Receptors (CARs)

[0243] The present application in some embodiments provides chimeric antigen receptors (CARs). In some embodiments, the present disclosure also provides CAR effector cells (e.g., T cells) that comprise, express, or are associated with a CAR. Such effector cells are also referred to herein as “CAR effector cells”, e.g., “CAR immune cells” or “CAR T cells”. In some embodiments, the anti-MSLN construct provided herein is a CAR (also referred to herein as an “anti-MSLN CAR”) comprising an anti-MSLN antibody moiety (such as any one of the anti- MSLN antibody moieties described in the “Anti-MSLN Antibody Moieties” section). In some embodiments, the present disclosure also provides CAR effector cells (e.g., T cells) that comprise, express, or are associated with an anti-MSLN CAR. Such effector cells are also referred to herein as “anti-MSLN CAR effector cells”, e.g., “anti-MSLN CAR immune cells” or “anti-MSLN CAR T cells”. In some embodiments, the anti-MSLN CAR provided herein is a bispecific anti-MSLN CAR (e.g., a dual-targeting CAR) that further comprises at least one other antibody moiety that specifically binds to at least one other target. The features of CARs described in this section apply to anti-MSLN CARs, bispecific anti-MSLN CARs, and CARs that do not target MSLN.

[0244] In some embodiments, the chimeric receptor is a CAR, such as an anti-MSLN CAR. In some embodiments, the CAR is a bispecific CAR (e.g., a dual-targeting CAR). In some embodiments, the CAR comprises a) an extracellular domain comprising an antibody moiety that specifically binds to a target and b) an intracellular signaling domain. In some embodiments, the CAR comprises a transmembrane domain between the extracellular domain and theintracellular domain. In some embodiments, the CAR further comprises a spacer. In some embodiments, the spacer connects the extracellular domain and the transmembrane domain of the CAR. In some embodiments, the spacer connects the intracellular domain and the transmembrane domain of the CAR. In some embodiments, the spacer domain is any oligo- or polypeptide that functions to link the transmembrane domain to the extracellular domain or the intracellular domain in the polypeptide chain. For example, a spacer domain may comprise up to about 300 amino acids, including for example between about 10 and about 100 amino acids, or between about 25 and about 50 amino acids.

[0245] In some embodiments, the CAR comprises a transmembrane domain that naturally is associated with one of the sequences in the CAR’s intracellular domain. For example, if a CAR intracellular domain comprises a CD28 co-stimulatory sequence, the transmembrane domain of the CAR is derived from the CD28 transmembrane domain. In some embodiments, the CAR comprises a transmembrane domain that has been selected or modified by amino acid substitution to minimize interactions with other members of the receptor complex and / or to avoid binding to the transmembrane domains of the same or different surface membrane proteins.

[0246] The intracellular signaling domain of the CAR is responsible for activation of at least one of the normal effector functions of the immune cell in which the CAR is expressed. Effector function of a T cell, for example, may be cytolytic activity or helper activity, including the secretion of cytokines. Thus, in some embodiments, the term “intracellular signaling domain” refers to the portion of a CAR that transduces the effector function signal and directs the cell to perform a specialized function.

[0247] It is known that signals generated through the TCR alone are insufficient for full activation of the T cell and that a secondary or co-stimulatory signal is also required. Thus, T cell activation can be said to be mediated by two distinct classes of intracellular signaling sequences: those that initiate antigen-dependent primary activation through the TCR (primary signaling sequences or primary immune cell signaling sequences) and those that act in an antigen-independent manner to provide a secondary or co-stimulatory signal (co-stimulatory signaling sequences).

[0248] Primary signaling sequences, or primary immune cell signaling sequences, regulate primary activation of the TCR complex in a stimulatory way or in an inhibitory way. Primary signaling sequences that act in a stimulatory manner may contain signaling motifs which areknown as immunoreceptor tyrosine-based activation motifs (or IT AMs). Thus, in some embodiments, the CAR comprises one or more IT AMs. In some embodiments, the CAR comprises a primary immune cell signaling sequence derived from, without limitation, TCR^, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, and CD66d. In some embodiments, the CAR further comprises a costimulatory signaling sequence. In some embodiments, the costimulatory signaling sequence is a portion of the intracellular domain of a costimulatory molecule including, for example, CD27, CD28, 4-1BB (CD137), 0X40, CD30, CD40, PD-1, ICOS, lymphocyte function-associated antigen-1 (LFA-1), CD2, CD7, LIGHT, NKG2C, B7-H3, a ligand that specifically binds with CD83, and the like. In some embodiments, the CAR comprises more than one costimulatory signaling sequence.

[0249] In some embodiments, the CAR comprises a primary immune cell signaling sequence derived from CD3^. In some embodiments, the CAR comprises a primary immune cell signaling sequence derived from CD3^ by itself or combined with any other desired intracellular signaling sequence(s) useful in the context of the CAR provided herein. For example, in some embodiments, the CAR comprises an intracellular domain that comprises a primary immune cell signaling sequence derived from CD3^ and a costimulatory signaling sequence. In some embodiments, the costimulatory signaling sequence is a portion of the intracellular domain of a costimulatory molecule including, for example, CD27, CD28, 4-1BB (CD137), 0X40, CD30, CD40, PD-1, ICOS, lymphocyte function-associated antigen- 1 (LFA-1), CD2, CD7, LIGHT, NKG2C, B7-H3, a ligand that specifically binds with CD83, and the like. In some embodiments, the costimulatory signaling sequence is derived from CD28 and 0X40 or CD28 and ICOS. In some embodiments, the intracellular signaling domain of the CAR comprises a primary immune cell signaling sequence derived from CD3(^ and co stimulatory signaling sequences derived from at least one of CD27, CD28, 4-1BB (CD137), 0X40, CD30, CD40, PD-1, ICOS, LFA-1, CD2, CD7, LIGHT, NKG2C, B7-H3, a ligand that specifically binds with CD83, and the like. In some embodiments, the CAR comprises more than one costimulatory signaling sequence.

[0250] In some embodiments, the CAR comprises the intracellular signaling domain that comprises a primary immune cell signaling sequence derived from CD3(^ and a costimulatory signaling sequence derived from CD28. In some embodiments, the CAR comprises the intracellular signaling domain that comprises a primary immune cell signaling sequence derived from CD3(^ and a costimulatory signaling sequence derived from CD30. In some embodiments, the CAR comprises the intracellular signaling domain that comprises a primary immune cellsignaling sequence derived from CD3^ and a costimulatory signaling sequence derived from 4- 1BB. In some embodiments, the intracellular signaling domain of the CAR comprises a primary immune cell signaling sequence derived from CD3^ and costimulatory signaling sequences derived from CD28 and 4-1BB. In some embodiments, the intracellular signaling domain of the CAR comprises a primary immune cell signaling sequence derived from CD3^ and costimulatory signaling sequences derived from CD30.

[0251] In some embodiments, the CAR comprises a target-binding domain (e.g., an antibody moiety) that specifically binds an MSLN. In some embodiments, the CAR comprises a targetbinding domain (e.g., an antibody moiety) that does not specifically bind an MSLN. In some embodiments, the CAR comprises two or more target-binding domains (e.g., antibody moieties) that specifically bind to the same or different targets. In some embodiments, the CAR is monospecific. In some embodiments, the CAR is multispecific, such as bispecific.

[0252] In some embodiments, the target-binding domain is a single-chain antibody moiety, such as an scFv. In some embodiments, the target-binding domain is an extracellular domain of a receptor or a ligand. In some embodiments, the target-binding domain is monospecific. In some embodiments, the target-binding domain is multispecific, e.g., bispecific. In some embodiments, the target-binding domain specifically binds an MSLN ECD. In some embodiments, the targetbinding domain specifically binds an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the target-binding domain specifically binds a cell-surface antigen. In some embodiments, the target-binding domain specifically binds an antigenic peptide / MHC class I complex.

[0253] In some embodiments, the target-binding domain specifically binds a target expressed or present on a cancer cell. In some embodiments, the target-binding domain specifically binds a target expressed or present on a mesothelioma, epithelioid mesothelioma, malignant pleural mesothelioma, pancreatic cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, ovarian cancer, ovarian serous adenocarcinoma, endometrial cancer, cervical cancer, lung adenocarcinoma, non- small cell lung cancer, AML / CLL, melanoma, gastrointestinal cancer, breast cancers (including metastatic breast cancer), glioma, prostate cancer, or a biliary cancer cell. In some embodiments, the target-binding domain specifically binds an MSLN ECD. In some embodiments, the anti-MSLN CAR comprises a first target-binding domain that specifically binds an MSLN ECD (e.g., an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2) and a second target-binding domain that specifically binds to a different regionof the MSLN ECD than the region of the MSLN ECD that is specifically bound by the first target-binding domain. In some embodiments, the second target-binding domain specifically binds to the same region of the MSLN ECD as the region of the MSLN ECD that is specifically bound by the first target-binding domain, but specifically binds an epitope that is nonoverlapping with the epitope specifically bound by the first target-binding domain. In some embodiments, the anti-MSLN CAR comprises a first target-binding domain that specifically binds an MSLN ECD and a second target-binding domain that specifically binds a different target (e.g., a non-MSLN-ECD target). In some embodiments, the anti-MSLN CAR comprises a first target-binding domain that specifically binds an MSLN ECD and a second target-binding domain that specifically binds a cell-surface antigen. In some embodiments, the anti-MSLN CAR comprises a second target-binding domain that specifically binds an MSLN ECD and a first target-binding domain that specifically binds a cell-surface antigen. In some embodiments, the cell-surface antigen is selected from the group consisting of ROR1, ROR2, EpCAM, MUC1, MUC16, ERa, RORA, EGFR, GPRC5D, GPC3, HER2, HER3, DLL3, c-Met, BCMA, CD19, CD22, EGFRvIII, PSMA, and p53. In some embodiments, the anti-MSLN CAR comprises a first target-binding domain that specifically binds an MSLN ECD and a second target-binding domain that specifically binds an antigenic peptide / MHC class I complex. In some embodiments, the anti-MSLN CAR comprises a second target-binding domain that specifically binds an MSLN ECD and a first target-binding domain that specifically binds an antigenic peptide / MHC class I complex. In some embodiments, the antigenic peptide is derived from a protein selected from the group consisting of MSLN, WT1, NDC80, KRAS, AFP, NY-ESO-1, HPV16-E7, PRAME, PSA, and Histone H3.3.

[0254] In some embodiments, there is provided an anti-MSLN CAR comprising a) an extracellular domain comprising any one of the anti-MSLN antibody moieties described herein (e.g., scFv) that specifically binds to an MSLN ECD, b) a transmembrane domain, and c) an intracellular signaling domain. In some embodiments, the MSLN ECD comprises the amino acid sequence of SEQ ID NO: 2. In some embodiments, the intracellular signaling domain is capable of activating an immune cell. In some embodiments, the intracellular signaling domain comprises a primary signaling sequence and a co- stimulatory signaling sequence. In some embodiments, the primary signaling sequence comprises a CD3^ intracellular signaling sequence. In some embodiments, the co- stimulatory signaling sequence comprises a CD28 and / or 4- IBB intracellular signaling sequence. In some embodiments, the intracellular domaincomprises a CD3^ intracellular signaling sequence and a CD28 and / or 4- IBB intracellular signaling sequence.

[0255] In some embodiments, the anti-MSLN CAR comprises an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties provided herein. In some embodiments, the anti-MSLN CAR comprises the anti-MSLN antibody moiety of Clone A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, or A46. In some embodiments, the anti-MSLN CAR comprises: a) any one of the anti-MSLN antibody moieties of Clone A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, or A46; b) a transmembrane module; and c) an intracellular signaling domain.

[0256] In some embodiments, the CAR comprises an intracellular signaling domain that comprises a primary immune cell signaling sequence derived from CD3^ and a costimulatory signaling sequence derived from CD28. In some embodiments, the CAR comprises the intracellular signaling domain that comprises a primary immune cell signaling sequence derived from CD3(^ and a costimulatory signaling sequence derived from CD30. In some embodiments, the CAR comprises the intracellular signaling domain that comprises a primary immune cell signaling sequence derived from CD3^ and a costimulatory signaling sequence derived from 4- 1BB. In some embodiments, the intracellular signaling domain of the CAR comprises a primary immune cell signaling sequence derived from CD3^ and costimulatory signaling sequences derived from CD28 and 4-1BB. In some embodiments, the intracellular signaling domain of the CAR comprises a primary immune cell signaling sequence derived from CD3^ and costimulatory signaling sequences derived from CD28 and 0X40 or CD28 and ICOS. In some embodiments, the intracellular signaling domain of the CAR comprises a primary immune cell signaling sequence derived from CD3^ and costimulatory signaling sequences derived from at least one of CD27, CD28, 4-1BB (CD137), 0X40, CD30, CD40, PD-1, ICOS, LFA-1, CD2, CD7, LIGHT, NKG2C, B7-H3, a ligand that specifically binds with CD83, and the like.

[0257] In some embodiments, the anti-MSLN CAR comprises an anti-MSLN antibody moiety comprising VH and VL comprising the amino acid sequence of SEQ ID NOs: 16 and 17, respectively, SEQ ID NOs: 32 and 33, respectively, SEQ ID NOs: 48 and 49, respectively, SEQ ID NOs: 64 and 65, respectively, SEQ ID NOs: 82 and 83, respectively, SEQ ID NOs: 98 and 99, respectively, SEQ ID NOs: 114 and 115, respectively, SEQ ID NOs: 130 and 131, respectively, SEQ ID NOs: 147 and 148, respectively, SEQ ID NOs: 163 and 164, respectively, SEQ ID NOs: 177 and 178, respectively, SEQ ID NOs: 361 and 362, respectively, or SEQ IDNOs: 375 and 376, respectively; or variants thereof having, individually, at least about 95% (for example at least about any of 96%, 97%, 98%, or 99%) sequence identity. In some embodiments, the anti-MSLN CAR comprises an anti-MSLN antibody moiety comprising VH and VL comprising the amino acid sequence of SEQ ID NOs: 16 and 17, respectively, SEQ ID NOs: 32 and 33, respectively, SEQ ID NOs: 48 and 49, respectively, SEQ ID NOs: 64 and 65, respectively, SEQ ID NOs: 82 and 83, respectively, SEQ ID NOs: 98 and 99, respectively, SEQ ID NOs: 114 and 115, respectively, SEQ ID NOs: 130 and 131, respectively, SEQ ID NOs: 147 and 148, respectively, SEQ ID NOs: 163 and 164, respectively, SEQ ID NOs: 177 and 178, respectively, SEQ ID NOs: 361 and 362, respectively, or SEQ ID NOs: 375 and 376, respectively.

[0258] In some embodiments, the anti-MSLN CAR is a bispecific anti-MSLN CAR. In some embodiments, the bispecific anti-MSLN CAR specifically binds an MSLN ECD, such as an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2, and at least one other target. In some embodiments, the bispecific anti-MSLN CAR comprises an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties provided herein, and an antibody moiety that specifically binds to the at least one other target. In some embodiments, the at least one other target is a different region of an MSLN ECD, such as an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the at least one other target is the same region of an MSLN ECD, such as an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2, but a non-overlapping epitope. In some embodiments, the at least one other target is not an MSLN ECD (e.g., a non-MSLN-ECD target). In some embodiments, the at least one other target is expressed on a cancer cell. In some embodiments, the at least one other target is expressed on a mesothelioma, epithelioid mesothelioma, malignant pleural mesothelioma, pancreatic cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, ovarian cancer, ovarian serous adenocarcinoma, endometrial cancer, cervical cancer, lung adenocarcinoma, non- small cell lung cancer, AML, CLL, melanoma, gastrointestinal cancer, breast cancer (including metastatic breast cancer), glioma, prostate cancer, or a biliary cancer cell. In some embodiments, the at least one other target is a cell-surface antigen. In some embodiments, the cell-surface antigen is ROR1, ROR2, EpCAM, MUC1, MUC16, FRa, RORA, EGFR, GPRC5D, GPC3, HER2, HER3, DLL3, c-Met, BCMA, CD19, CD22, EGFRvIII, PSMA, or p53. In some embodiments, the at least one other target is a complex comprising an antigenic peptide and an MHC class I protein (an antigenic peptide / MHC class I complex). Insome embodiments, the antigenic peptide is derived from MSLN, WT1, NDC80, KRAS, AFP, NY-ESO-1, HPV16-E7, PRAME, PSA, or Histone H3.3.Chimeric Antibody-T Cell Receptor (TCR) Constructs (caTCRs)

[0259] In some embodiments, provided herein is a chimeric antibody-T cell receptor construct (caTCR). Such construct is also referred to herein as a “caTCR.” Exemplary caTCRs are discussed in US 10098951B2, the contents of which are incorporated herein by reference in their entirety. In some embodiments, the caTCR specifically bind to a target and is capable of associating with at least one TCR-associated signaling molecule (such as CD35s, CD3ys, and / or CD3( ). In some embodiments, the caTCR does not comprise a variable domain of a TCR. In some embodiments, the caTCR does not comprise a constant domain of a TCR.

[0260] As described in further detail below, the present disclosure also provides an effector cell (e.g., T cell) that comprises, expresses, or is associated with a caTCR, such as an anti-MSLN caTCR. Such effector cells are also referred to herein as “caTCR effector cells” (e.g., “caTCR T cells”), including “anti-MSLN caTCR effector cells” (e.g., “anti-MSLN caTCR T cells”). In some embodiments, the anti-MSLN caTCR is a bispecific anti-MSLN caTCR (e.g., a dualtargeting caTCR) that further comprises at least one other antibody moiety that specifically binds to at least one other target. The features of caTCRs described in this section apply to anti-MSLN caTCRs, bispecific anti-MSLN caTCRs, and caTCRs that do not target MSLN.

[0261] In some embodiments, the caTCR comprises a) an antigen-binding module, and b) a T cell receptor module (TCRM) comprising a first TCR domain (TCRD) comprising a first TCR transmembrane domain (TCR-TM) derived from one of the transmembrane domains of a naturally occurring TCR (such as an aPTCR or a ySTCR) and a second TCRD comprising a second TCR-TM derived from the other transmembrane domain of the naturally occurring TCR (such as an aPTCR or a ySTCR), wherein the TCRM is capable of associating with at least one TCR-associated signaling molecule (such as CD35s, CD3ys, and / or CD3( ), and wherein the antibody moiety is linked to the first and / or second TCRDs. In some embodiments, the first TCR-TM and the second TCR-TM are derived from a y / 8 TCR. In some embodiments, the first TCR-TM is derived from TCRy and the second TCR-TM is derived from TCR5. In some embodiments, the first TCR-TM is derived from a TCR 5 chain and the second TCR-TM is derived from TCRy. In some embodiments, the first TCR-TM and the second TCR-TM are derived from an oc / TCR. In some embodiments, the first TCR-TM is derived from TCRoc chainand the second TCR-TM is derived from TCR|3. In some embodiments, the first TCR-TM is derived from TCR|3 and the second TCR-TM is derived from TCRoc. In some embodiments, the caTCR comprises naturally occurring TCR domains. In some embodiments, the caTCR comprises at least one non-naturally occurring TCR domain. For example, the y / 8 TCR, the oc / |3 TCR, the TCRy chain, the TCR8 chain, the TCRoc chain, and / or the TCR|3 chain may be naturally occurring or non-naturally occurring. The antigen-binding module of the anti-MSLN caTCR provides the antigen specificity and a TCRM that allows for CD3 recruitment and signaling. In some embodiments, the antigen-binding module is not a naturally occurring T cell receptor antigen-binding moiety. In some embodiments, the antigen-binding module is linked to the N-terminus of a polypeptide chain in the TCRM. In some embodiments, the antigen binding module is an antibody moiety selected from the group consisting of a Fab, a Fab’, a F(ab’)2, an Fv, and an scFv. The TCRM comprises a transmembrane module derived from the transmembrane domains of one or more TCRs (TCR-TMs), such as an a / p and / or y / 8 TCR, and optionally further comprises one or both of the connecting peptides or fragments thereof of a TCR and / or one or more TCR intracellular domains or fragments thereof. In some embodiments, the TCRM comprises two polypeptide chains, each polypeptide chain comprising, from N- terminus to C-terminus, a connecting peptide, a transmembrane domain, and optionally a TCR intracellular domain. In some embodiments, the TCRM comprises one or more non-naturally occurring TCR domains. For example, in some embodiments, the TCRM comprises one or two non-naturally occurring TCR transmembrane domains. A non-naturally occurring TCR domain may be a corresponding domain of a naturally occurring TCR modified by substitution of one or more amino acids, and / or by replacement of a portion of the corresponding domain with a portion of an analogous domain from another TCR. In some embodiments, the anti-MSLN caTCR comprises a first polypeptide chain and a second polypeptide chain, wherein the first and second polypeptide chains together form the antigen -binding module and the TCRM. In some embodiments, the first and second polypeptide chains are separate polypeptide chains, and the caTCR is a multimer, such as a dimer. In some embodiments, the first and second polypeptide chains are covalently linked, such as by a peptide linkage, or by another chemical linkage, such as a disulfide linkage. In some embodiments, the first polypeptide chain and the second polypeptide chain are linked by at least one disulfide bond. In some embodiments, the caTCR further comprises one or more T cell co- stimulatory signaling sequences. The one or more costimulatory signaling sequences can be, individually, all or a portion of the intracellular domainof a co- stimulatory molecule including, for example, CD27, CD28, 4-1BB (CD137), 0X40, CD30, CD40, ICOS, lymphocyte function- associated antigen- 1 (LFA-1), CD2, CD7, LIGHT, NKG2C, B7-H3, a ligand that specifically binds with CD83, and the like. In some embodiments, the one or more co- stimulatory signaling sequences are between the first TCR-TM and the first TCR intracellular domain and / or between the second TCR-TM and the second TCR intracellular domain. In some embodiments, the one or more co- stimulatory signaling sequences are C- terminal to the first TCRD and / or the second TCRD. In some embodiments, the caTCR lacks a T cell co- stimulatory signaling sequence. In some embodiments, the caTCR lacks a functional primary immune cell signaling domain of a TCR-associated T cell activation molecule selected from the group consisting of CD3(^ (TCRQ, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, and CD66d. In some embodiments, the caTCR lacks a functional primary immune cell signaling domain. In some embodiments, the caTCR lacks any primary immune cell signaling sequences. In some embodiments, the caTCR further comprises a stabilization module comprising a first stabilization domain and a second stabilization domain, wherein the first and second stabilization domains have a binding affinity for each other that stabilizes the caTCR. In some embodiments, the stabilization module is located between the antigen-binding module and the TCRM. In some embodiments, the stabilization module comprises an antibody constant domain or a TCR constant domain, or a fragment thereof. In some embodiments, the stabilization module comprises a pair of antibody constant domains selected from the group consisting of CHI-CL, CH2-CH2, CH3-CH3, and CH4-CH4, or fragments thereof. In some embodiments, the stabilization module comprises a pair of TCR constant domains selected from the group consisting of Ca-CP and Cy-C5, or fragments thereof. In some embodiments, the caTCR further comprises a spacer module between any two caTCR modules or domains. In some embodiments, the spacer module comprises one or more peptide linkers connecting two caTCR modules or domains.

[0262] In some embodiments, a caTCR comprises a first polypeptide chain and a second polypeptide chain, in which the first polypeptide chain comprises an antibody VH fused to a first antibody constant domain (e.g., CHI) fused to a transmembrane domain and an intracellular immune cell signaling domain, and the second polypeptide comprises a second antibody VL fused to an antibody constant domain (e.g., CL) fused to a transmembrane domain and an intracellular immune cell signaling domain. In some embodiments, the first and second polypeptide chains are linked, such as by a covalent linkage (e.g., peptide or other chemicallinkage) or non-covalent linkage. In some embodiments, the caTCR is a heterodimer comprising the first polypeptide chain and the second polypeptide chain. In some embodiments, the first polypeptide chain and the second polypeptide chain are linked by at least one disulfide bond. A caTCR as used herein is non-naturally occurring. In some embodiments, the first antibody constant domain and the second antibody constant domain are selected from the group consisting of CH1-CL, CH2-CH2, CH3-CH3, and CH4-CH4. In some embodiments, the caTCR does not comprise variable domains of a TCR.

[0263] In some embodiments, the caTCR comprises: a) a first polypeptide chain comprising a first antigen-binding domain comprising a Vn, a first stabilization domain comprising a CHI, and a TCRD comprising a first transmembrane domain of a first TCR subunit; and b) a second polypeptide chain comprising a second antigen-binding domain comprising a VL, a second stabilization domain comprising a CL, and a second TCRD comprising a second transmembrane domain of a second TCR subunit, wherein the VH of the first antigen-binding domain and the VL of the second antigen-binding domain form an antigen-binding module that specifically binds to a target (e.g., an MSLN), wherein the CHI of the first stabilization domain and the CL of the second stabilization domain form a stabilization module, and wherein the first TCRD and the second TCRD form a TCRM that is capable of associating with at least one TCR-associated signaling module. In some embodiments, the stabilization module comprises a disulfide bond between a residue in the CHI and a residue in the CL. In some embodiments, the CHI is fused to the first TCRD via a first hinge region, and the CL is fused to the second TCRD via a second hinge region. In some embodiments, the CHI is fused to the first TCRD via a first peptide linker, and the CL is fused to the second TCRD via a second peptide linker.

[0264] In some embodiments, the caTCR comprises: a) a first polypeptide chain comprising a first antigen-binding domain comprising a VH and a first TCRD comprising a first transmembrane domain of a first TCR subunit; and b) a second polypeptide chain comprising a second antigen-binding domain comprising a VL and a second TCRD comprising a second transmembrane domain of a second TCR subunit, wherein the VH of the first antigen-binding domain and the VL of the second antigen-binding domain form an antigen-binding module, wherein the first TCRD and the second TCRD form a TCRM that is capable of associating with at least one TCR-associated signaling module. In some embodiments, the caTCR does not comprise an antibody constant domain.

[0265] In some embodiments, the caTCR comprises: a) a first polypeptide chain comprising a first antigen-binding domain comprising a first VH, a first stabilization domain comprising a first CHI, and a first TCRD comprising a first transmembrane domain of a first TCR subunit; b) a second polypeptide chain comprising a second antigen-binding domain comprising a first VL, and a second stabilization domain comprising a first CL; C) a third polypeptide chain comprising a third antigen-binding domain comprising a second VH, a third stabilization domain comprising a second CHI, and a second TCRD comprising a second transmembrane domain of a second TCR subunit; and d) a fourth polypeptide chain comprising a fourth antigen-binding domain comprising a second VL, and a fourth stabilization domain comprising a second CL, wherein the first VH of the first antigen-binding domain and the first VL of the second antigen-binding domain form a first antigen-binding module that specifically binds to a first target, wherein the second VH of the third antigen-binding domain and the second VL of the fourth antigen-binding domain form a second antigen-binding module that specifically binds to a second target, wherein the first CHI of the first stabilization domain and the first CL of the second stabilization domain form a first stabilization module, wherein the second CHI of the third stabilization domain and the second CL of the fourth stabilization domain form a second stabilization module, and wherein the first TCRD and the second TCRD form a TCRM that is capable of associating with at least one TCR-associated signaling module. In some embodiments, the first CHI is fused to the first TCRD via a first hinge region, and the second CHI is fused to the second TCRD via a second hinge region.

[0266] In some embodiments, the caTCR comprises: a) a first polypeptide chain comprising a first antigen-binding domain comprising an scFv domain and a first TCRD comprising a first transmembrane domain of a first TCR subunit; and b) a second polypeptide chain comprising a second TCRD comprising a second transmembrane domain of a second TCR subunit, wherein the first TCRD and the second TCRD form a TCRM that is capable of associating with at least one TCR-associated signaling module.

[0267] In some embodiments, the caTCR comprises: a) a first polypeptide chain comprising a first antigen-binding domain comprising a first scFv domain and a first TCRD comprising a first transmembrane domain of a first TCR subunit; and b) a second polypeptide chain comprising a second scFv domain and a second TCRD comprising a second transmembrane domain of a second TCR subunit, wherein the first TCRD and the second TCRD form a TCRM that is capable of associating with at least one TCR-associated signaling module. In someembodiments, the first scFv and the second scFv bind to the same target. In some embodiments, the first scFv and the second scFv bind to different targets.

[0268] In some embodiments, the caTCR comprises a TCRM that comprises a) a first TCRD comprising a first TCR-TM and b) a second TCRD comprising a second TCR-TM, wherein the TCRM is capable of associating with at least one TCR-associated signaling molecule. In some embodiments, both of the TCR-TMs are naturally occurring. In some embodiments, at least one of the TCR-TMs is non-naturally occurring. In some embodiments, both of the TCR-TMs are non-naturally occurring. In some embodiments, the first TCR-TM is derived from one of the transmembrane domains of a T cell receptor (such as an aPTCR or a ySTCR) and the second TCR-TM is derived from the other transmembrane domain of the T cell receptor. In some embodiments, the TCRM allows for enhanced association with the at least one TCR-associated signaling molecule as compared to a TCRM comprising the transmembrane domains of the T cell receptor. Association or recruitment of TCR-associated signaling molecules can be determined by methods known in the art, such as FACS analysis for TCR-CD3 complex surface expression or co-immunoprecipitation of CD3 subunits with the caTCR.

[0269] In some embodiments, the caTCR comprises an antigen-binding module that comprises a first antigen-binding domain comprising a VH (e.g., a VH of an anti-MSLN antibody moiety described herein) and a second antigen-binding domain comprising a VL (e.g., a VL of an anti- MSLN antibody moiety described herein). In some embodiments, the VH and VL CDRS are derived from the same anti-MSLN antibody moiety. In some embodiments, some of the VH and VL CDRS are derived from different antibody moieties. In some embodiments, the VH and / or VL are human, humanized, chimeric, semi-synthetic, or fully synthetic.

[0270] In some embodiments, the caTCR comprises an antigen-binding module linked to a TCRM described herein, optionally including a stabilization module. For example, in some embodiments, the caTCR comprises the antigen-binding module linked to the N-terminus of one or both of the TCRDs. In some embodiments, the caTCR comprises a stabilization module between a TCRM and an antigen-binding module. In some embodiments, the caTCR further comprises a spacer module between any two caTCR modules or domains. In some embodiments, the spacer module comprises one or more peptide linkers between about 5 to about 70 (such as about any of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70, including any ranges between these values) amino acids in length. In some embodiments, the caTCR further comprises one or more accessory intracellular domains. In some embodiments, the one or more accessoryintracellular domains are carboxy-terminal to the first and / or second TCRD. In some embodiments, the one or more accessory intracellular domains are between the first TCR-TM and the first TCR intracellular domain and / or between the second TCR-TM and the second TCR intracellular domain. In some embodiments, the one or more accessory intracellular domains comprise, individually, a T-cell costimulatory domain. In some embodiments, the T-cell costimulatory domain comprises all or a portion of the intracellular domain of an immune costimulatory molecule (such as CD27, CD28, 4-1BB (CD137), 0X40, CD30, CD40, ICOS, lymphocyte function-associated antigen-1 (LFA-1), CD2, CD7, LIGHT, NKG2C, B7-H3, a ligand that specifically binds with CD83, and the like).

[0271] In some embodiments, the caTCR comprises a) an antigen-binding module comprising an antibody moiety, and b) a TCRM comprising a first TCRD comprising a first TCR-TM derived from one of the transmembrane domains of a naturally occurring TCR (such as an aPTCR or a ySTCR) and a second TCRD comprising a second TCR-TM derived from the other transmembrane domain of the naturally occurring TCR (such as an aPTCR or a ySTCR), wherein the TCRM is capable of associating with at least one TCR-associated signaling molecule (such as CD35s, CD3ys, and / or CD3( ), and wherein the antibody moiety is linked to the first and / or second TCRDs.

[0272] In some embodiments, the anti-MSLN construct is an anti-MSLN caTCR comprising an anti-MSLN antibody moiety (such as any one of the anti-MSLN antibody moieties described in the “Anti-MSLN Antibody Moieties” section). Such construct is also referred to herein as an “anti-MSLN caTCR.” In some embodiments, the anti-MSLN caTCR specifically binds to an MSLN and is capable of associating with at least one TCR-associated signaling molecule (such as CD35s, CD3ys, and / or CD3( ). In some embodiments, the caTCR does not comprise a constant domain of a TCR.

[0273] In some embodiments, the anti-MSLN caTCR comprises a first polypeptide chain and a second polypeptide chain, in which the first polypeptide chain comprises an antibody VH fused to an antibody CHI fused to a transmembrane domain and an intracellular immune cell signaling domain, and the second polypeptide comprises an antibody VL fused to an antibody CL fused to a transmembrane domain and an intracellular immune cell signaling domain. In some embodiments, the first and second polypeptide chains are linked, such as by a covalent linkage (e.g., peptide or other chemical linkage) or non-covalent linkage. In some embodiments, the anti-MSLN caTCR is a heterodimer comprising the first polypeptide chain and the secondpolypeptide chain. In some embodiments, the first polypeptide chain and the second polypeptide chain are linked by at least one disulfide bond. The specificity of the anti-MSLN caTCR derives from an anti-MSLN antibody moiety that confers binding specificity to an MSLN ECD. An anti- MSLN caTCR as used herein is non-naturally occurring.

[0274] In some embodiments, the comprises a target-binding domain (e.g., an antibody moiety) that specifically binds an MSLN ECD (e.g., an anti-MSLN caTCR). In some embodiments, the caTCR comprises a target-binding domain (e.g., an antibody moiety) that does not specifically bind an MSLN ECD. In some embodiments, the caTCR comprises two or more target-binding domains (e.g., antibody moieties) that specifically bind to the same or different targets. In some embodiments, the caTCR is monospecific. In some embodiments, the caTCR is multispecific, such as bispecific.

[0275] In some embodiments, the target-binding domain is an antibody moiety, such as a Lab, a Lab’, a (Eab’ , an Ev, or an scEv. In some embodiments, the target-binding domain is an extracellular domain of a receptor or a ligand. In some embodiments, the target-binding domain is monospecific. In some embodiments, the target-binding domain is multispecific, e.g., bispecific. In some embodiments, the target-binding domain specifically binds an MSLN ECD. In some embodiments, the target-binding domain specifically binds an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the target-binding domain specifically binds a cell-surface antigen. In some embodiments, the target-binding domain specifically binds an antigenic peptide / MHC class I complex.

[0276] In some embodiments, the target-binding domain specifically binds a target expressed or present on a cancer cell. In some embodiments, the target-binding domain specifically binds a target expressed or present on a mesothelioma, epithelioid mesothelioma, malignant pleural mesothelioma, pancreatic cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, ovarian cancer, ovarian serous adenocarcinoma, endometrial cancer, cervical cancer, lung adenocarcinoma, non- small cell lung cancer, AML / CLL, melanoma, gastrointestinal cancer, breast cancers (including metastatic breast cancer), glioma, prostate cancer, or a biliary cancer cell. In some embodiments, the target-binding domain specifically binds an MSLN. In some embodiments, the anti-MSLN caTCR comprises a first target-binding domain that specifically binds an MSLN ECD (e.g., an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2) and a second target-binding domain that specifically binds to a different region of the MSLN ECD than the region of the MSLN ECD that is specifically bound by the first target-bindingdomain. In some embodiments, the second target-binding domain specifically binds to the same region of the MSLN ECD as the region of the MSLN ECD that is specifically bound by the first target-binding domain, but specifically binds an epitope that is non-overlapping with the epitope specifically bound by the first target-binding domain. In some embodiments, the caTCR comprises a first target-binding domain that specifically binds an MSLN ECD and a second target-binding domain that specifically binds a different target (e.g., a non-MSLN-ECD target). In some embodiments, the anti-MSLN caTCR comprises a first target-binding domain that specifically binds an MSLN ECD and a second target-binding domain that specifically binds a cell-surface antigen. In some embodiments, the anti-MSLN caTCR comprises a second targetbinding domain that specifically binds an MSLN ECD and a first target-binding domain that specifically binds a cell-surface antigen. In some embodiments, the cell-surface antigen is selected from the group consisting of ROR1, ROR2, EpCAM, MUC1, MUC16, FRa, RORA, EGFR, GPRC5D, GPC3, HER2, HER3, DLL3, c-Met, BCMA, CD19, CD22, EGFRvIII, PSMA, and p53. In some embodiments, the anti-MSLN caTCR comprises a first target-binding domain that specifically binds an MSLN ECD and a second target-binding domain that specifically binds an antigenic peptide / MHC class I complex. In some embodiments, the anti- MSLN caTCR comprises a second target-binding domain that specifically binds an MSLN ECD and a first target-binding domain that specifically binds an antigenic peptide / MHC class I complex. In some embodiments, the antigenic peptide is derived from a protein selected from the group consisting of MSLN, WT1, NDC80, KRAS, AFP, NY-ESO-1, HPV16-E7, PRAME, PSA, and Histone H3.3.

[0277] In some embodiments, the anti-MSLN caTCR comprises an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties provided herein. In some embodiments, the anti-MSLN caTCR comprises the anti-MSLN antibody moiety of Clone A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, or A46.

[0278] In some embodiments, the anti-MSLN caTCR comprises an anti-MSLN antibody moiety comprising VH and VL comprising the amino acid sequence of SEQ ID NOs: 16 and 17, respectively, SEQ ID NOs: 32 and 33, respectively, SEQ ID NOs: 48 and 49, respectively, SEQ ID NOs: 64 and 65, respectively, SEQ ID NOs: 82 and 83, respectively, SEQ ID NOs: 98 and 99, respectively, SEQ ID NOs: 114 and 115, respectively, SEQ ID NOs: 130 and 131, respectively, SEQ ID NOs: 147 and 148, respectively, SEQ ID NOs: 163 and 164, respectively, SEQ ID NOs: 177 and 178, respectively, SEQ ID NOs: 361 and 362, respectively, or SEQ IDNOs: 375 and 376, respectively; or variants thereof having, individually, at least about 95% (for example at least about any of 96%, 97%, 98%, or 99%) sequence identity. In some embodiments, the anti-MSLN caTCR comprises an anti-MSLN antibody moiety comprising VH and VL comprising the amino acid sequence of SEQ ID NOs: 16 and 17, respectively, SEQ ID NOs: 32 and 33, respectively, SEQ ID NOs: 48 and 49, respectively, SEQ ID NOs: 64 and 65, respectively, SEQ ID NOs: 82 and 83, respectively, SEQ ID NOs: 98 and 99, respectively, SEQ ID NOs: 114 and 115, respectively, SEQ ID NOs: 130 and 131, respectively, SEQ ID NOs: 147 and 148, respectively, SEQ ID NOs: 163 and 164, respectively, SEQ ID NOs: 177 and 178, respectively, SEQ ID NOs: 361 and 362, respectively, or SEQ ID NOs: 375 and 376, respectively.

[0279] In some embodiments, the anti-MSLN caTCR is a bispecific anti-MSLN caTCR. In some embodiments, the bispecific anti-MSLN caTCR specifically binds an MSLN ECD, such as an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2, and at least one other target. In some embodiments, the bispecific anti-MSLN caTCR comprises an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties provided herein, and an antibody moiety that specifically binds to the at least one other target. In some embodiments, the at least one other target is a different region of an MSLN ECD, such as an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the at least one other target is the same region of an MSLN ECD, such as an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2, but a non-overlapping epitope. In some embodiments, the at least one other target is not an MSLN ECD (e.g., a non-MSLN-ECD target). In some embodiments, the at least one other target is expressed on a cancer cell. In some embodiments, the at least one other target is expressed on a mesothelioma, epithelioid mesothelioma, malignant pleural mesothelioma, pancreatic cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, ovarian cancer, ovarian serous adenocarcinoma, endometrial cancer, cervical cancer, lung adenocarcinoma, non- small cell lung cancer, AML, CLL, melanoma, gastrointestinal cancer, breast cancer (including metastatic breast cancer), glioma, prostate cancer, or a biliary cancer cell. In some embodiments, the at least one other target is a cellsurface antigen. In some embodiments, the cell-surface antigen is ROR1, ROR2, EpCAM, MUC1, MUC16, FRa, RORA, EGFR, GPRC5D, GPC3, HER2, HER3, DLL3, c-Met, BCMA, CD19, CD22, EGFRvIII, PSMA, or p53. In some embodiments, the at least one other target is a complex comprising an antigenic peptide and an MHC class I protein (an antigenicpeptide / MHC class I complex). In some embodiments, the antigenic peptide is derived fromMSLN, WT1, NDC80, KRAS, AFP, NY-ESO-1, HPV16-E7, PRAME, PSA, or Histone H3.3.Chimeric Stimulatory Receptor Constructs ( CSRs)

[0280] Also provided herein are MSLN-specific chimeric stimulatory receptor constructs, which are alternatively referred to herein as chimeric signaling receptor constructs (z.e., “anti- MSLN CSRs”). In some embodiments, there is provided MSLN-specific chimeric stimulatory receptor constructs, which are alternatively referred to herein as chimeric signaling receptor constructs (z.e., “anti-MSLN CSRs”), comprising an anti-MSLN antibody moiety (such as any one of the anti-MSLN antibody moieties described in the “Anti-MSLN Antibody Moieties” section). In some embodiments, the anti-MSLN CSR is a bispecific anti-MSLN CSR (e.g., a dual-targeting CSR) that further comprises at least one other antibody moiety that specifically binds to at least one other target. The features of CSRs described in this section apply to anti- MSLN CSRs, bispecific anti-MSLN CSRs, and CSRs that do not target MSLN.

[0281] Exemplary CSRs are discussed in US 2021 / 0107976, the contents of which are incorporated herein by reference in their entirety. In some embodiments, the CSR is expressed on the surface of an immune cell (such as a T cell). The CSR binds to a target, and upon binding to the target, is capable of stimulating the immune cell on which the CSR is expressed. In some embodiments, the CSR is a bispecific CSR. In some embodiments, the CSR comprises a targetbinding module, a transmembrane module, and a co-stimulatory immune cell signaling module that allows for stimulating the immune cell in or on which the CSR is expressed. In some embodiments, the CSR lacks a functional primary immune cell signaling sequence. In some embodiments, the CSR lacks a primary immune cell signaling sequence. In some embodiments, the CSR comprises a single polypeptide chain comprising the target-binding module, transmembrane module, and co-stimulatory signaling module. In some embodiments, the CSR comprises a first polypeptide chain and a second polypeptide chain, wherein the first and second polypeptide chains together form the target-binding module, the transmembrane module, and the co-stimulatory signaling module. In some embodiments, the first and second polypeptide chains are separate polypeptide chains, and the CSR is a multimer, such as a dimer. In some embodiments, the first and second polypeptide chains are covalently linked, such as by a peptide linkage, or by another chemical linkage, such as a disulfide linkage. In some embodiments, thefirst polypeptide chain and the second polypeptide chain are linked by at least one disulfide bond.

[0282] Also provided are effector cells (such as T cells) expressing a CSR of the present disclosure. Such effector cells (such as T cells) are produced by introducing (e.g., transducing or transfecting) a nucleic acid encoding a CSR described herein (or a vector comprising such a nucleic acid) into the effector cell (e.g., T cell).

[0283] Examples of co- stimulatory immune cell signaling domains for use in a CSR include, but are not limited to, the cytoplasmic sequences of co-receptors of the T cell receptor, which can act in concert with a caTCR to initiate signal transduction following caTCR engagement, as well as any derivative or variant of these sequences and any synthetic sequence that has the same functional capability. Thus, in some embodiments provided is an effector cell (such as a T cell) that expresses a caTCR and a CSR. Effector cells (such as T cells) expressing a caTCR and a CSR (z.e., “caTCR + CSR effector cells”) are described in further detail below.

[0284] It is known that signals generated through the TCR alone are insufficient for full activation of the T cell and that a secondary or co -stimulatory signal is also required. Thus, T cell activation can be said to be mediated by two distinct classes of intracellular signaling sequence: those that initiate antigen-dependent primary activation through the TCR (referred to herein as “primary T cell signaling sequences”) and those that act in an antigen-independent manner to provide a secondary or co-stimulatory signal (referred to herein as “co- stimulatory T cell signaling sequences”).

[0285] Primary immune cell signaling sequences that act in a stimulatory manner may contain IT AMs. Examples of ITAM-containing primary immune cell signaling sequences include those derived from CD3^ (TCRQ, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, and CD66d. A “functional” primary immune cell signaling sequence is a sequence that is capable of transducing an immune cell activation signal when operably coupled to an appropriate receptor. “Non-functional” primary immune cell signaling sequences, which may comprise fragments or variants of primary immune cell signaling sequences, are unable to transduce an immune cell activation signal. Thus, in some embodiments, a CSR described herein lacks a functional primary immune cell signaling sequence, such as a functional signaling sequence comprising an IT AM. In some embodiments, the CSR described herein lacks any primary immune cell signaling sequence.

[0286] In some embodiments, the CSR comprises a co-stimulatory signaling module that comprises (such as consists of or consists essentially of) all or a portion of the intracellular signaling domain of an immune cell co-stimulatory molecule including, for example, CD27, CD28, 4-1BB (CD137), 0X40, CD30, CD40, ICOS, lymphocyte function-associated antigen-1 (LFA-1), CD2, CD7, LIGHT, NKG2C, B7-H3, a ligand that specifically binds with CD83, and the like. In some embodiments, the CSR comprises a fragment of an immune cell co-stimulatory molecule (fCSM), wherein the fCSM comprises the CSR transmembrane (TM) domain and CSR intracellular (IC) co-stimulatory signaling domain. Exemplary IC co-stimulatory immune cell signaling module sequences and signaling module sequence plus TM domains are provided below:4-1BB IC signaling sequence:KRGRKKLLYIFKQPFMRPVQTTQEEDGCSCRFPEEEEGGCEL (SEQ ID NO: 180)CD27 IC signaling sequence:QRRKYRSNKGESPVEPAEPCRYSCPREEEGSTIPIQEDYRKPEPACSP (SEQ ID NO: 181)CD28 IC signaling sequence:RSKRSRLLHSDYMNMTPRRPGPTRKHYQPYAPPRDFAAYRS (SEQ ID NO: 182)CD30 IC signaling sequence:HRRACRKRIRQKLHLCYPVQTSQPKLELVDSRPRRSSTQLRSGASVTEPVAEERGLMSQPLMETCHSVGAAYLESLPLQDASPAGGPSSPRDLPEPRVSTEHTNNKIEKIYIMKADTVIVGTVKAELPEGRGLAGPAEPELEEELEADHTPHYPEQETEPPLGSCSDVMLSVEEEGKEDPLPTAASGK (SEQ ID NO: 183)0X40 IC signaling sequence:ALYLLRRDQRLPPDAHKPPGGGSFRTPIQEEQADAHSTLAKI (SEQ ID NO: 184)ICOS IC signaling sequence:CWLTKKKYSSSVHDPNGEYMFMRAVNTAKKSRLTDVTL (SEQ ID NO: 185)DAP10 IC signaling sequence:CARPRRSPAQEDGKVYINMPGRG (SEQ ID NO: 186) myc tag + truncated CD28 sequence:EQKLISEEDLAAAIEVMYPPPYLDNEKSNGTIIHVKGKHLCPSPLFPGPSKPFWVLVVVGGVLACYSLLVTVAFIIFWVRSKRSRLLHSDYMNMTPRRPGPTRKHYQPYAPPRDFAAYRS (SEQ ID NO: 187) truncated CD28 sequence:IEVMYPPPYLDNEKSNGTIIHVKGKHLCPSPLFPGPSKPFWVLVVVGGVLACYSLLVTV AFIIFWVRSKRSRLLHSDYMNMTPRRPGPTRKHYQPYAPPRDFAAYRS (SEQ ID NO: 188) myc tag + truncated 4- IBB sequence:EOKLISEEDLAAATGPADLSPGASSVTPPAPAREPGHSPOIISFFLALTSTALLFLLFFLTL RFSVVKRGRKKLLYIFKQPFMRPVQTTQEEDGCSCRFPEEEEGGCEL (SEQ ID NO: 189) truncated 4-1BB sequence:AAATGPADLSPGASSVTPPAPAREPGHSPQIISFFLALTSTALLFLLFFLTLRFSVVKRGRK KLLYIFKQPFMRPVQTTQEEDGCSCRFPEEEEGGCEL (SEQ ID NO: 190) myc tag + truncated CD27 sequence:EOKLISEEDLAAATGPTHLPYVSEMLEARTAGHMOTLADFRQLPARTLSTHWPPORSL CSSDFIRILVIFSGMFLVFTLAGALFLHQRRKYRSNKGESPVEPAEPCRYSCPREEEGSTIP IQEDYRKPEPACSP (SEQ ID NO: 191) truncated CD27 sequence:AAATGPTHLPYVSEMLEARTAGHMQTLADFRQLPARTLSTHWPPQRSLCSSDFIRILVIF SGMFLVFTLAGALFLHQRRKYRSNKGESPVEPAEPCRYSCPREEEGSTIPIQEDYRKPEP ACSP (SEQ ID NO: 192) myc tag + truncated CD30 sequence:EQKLISEEDLAAATGAPPLGTOPDCNPTPENGEAPASTSPTOSLLVDSOASKTLPIPTSAP VALSSTGKPVLDAGPVLFWVILVLVVVVGSSAFLLCHRRACRKRIRQKLHLCYPVQTSQ PKLELVDSRPRRSSTQLRSGASVTEPVAEERGLMSQPLMETCHSVGAAYLESLPLQDAS PAGGPSSPRDLPEPRVSTEHTNNKIEKIYIMKADTVIVGTVKAELPEGRGLAGPAEPELEE ELEADHTPHYPEQETEPPLGSCSDVMLSVEEEGKEDPLPTAASGK (SEQ ID NO: 193) truncated CD30 sequence:AAATGAPPLGTQPDCNPTPENGEAPASTSPTQSLLVDSQASKTLPIPTSAPVALSSTGKPV LDAGPVLFWVILVLVVVVGSSAFLLCHRRACRKRIRQKLHLCYPVQTSQPKLELVDSRP RRSSTQLRSGASVTEPVAEERGLMSQPLMETCHSVGAAYLESLPLQDASPAGGPSSPRD LPEPRVSTEHTNNKIEKIYIMKADTVIVGTVKAELPEGRGLAGPAEPELEEELEADHTPH YPEQETEPPLGSCSDVMLSVEEEGKEDPLPTAASGK (SEQ ID NO: 194) myc tag + truncated 0X40 sequence:EQKLISEEDLAAATGDRDPPATOPOETOGPPARPITVQPTEAWPRTSOGPSTRPVEVPG GRAVAAILGLGLVLGLLGPLAILLALYLLRRDQRLPPDAHKPPGGGSFRTPIQEEQADAH STLAKI (SEQ ID NO: 195) truncated 0X40 sequence:AAATGDRDPPATQPQETQGPPARPITVQPTEAWPRTSQGPSTRPVEVPGGRAVAAILGL GLVLGLLGPLAILLALYLLRRDQRLPPDAHKPPGGGSFRTPIQEEQADAHSTLAKI (SEQ ID NO: 196) myc tag + CD8 TM sequence and CD27 IC signaling sequence:EQKLISEEDLAAATGTTTPAPRPPTPAPTIASOPLSLRPEACRPAAGGAVHTRGLDFACDIYIWAPLAGTGCVLLLSLVITLYCQRRKYRSNKGESPVEPAEPCRYSCPREEEGSTIPIQEDYRKPEPACSP (SEQ ID NO: 197)CD8 TM sequence and CD27 IC signaling sequence:AAATGTTTPAPRPPTPAPTIASQPLSLRPEACRPAAGGAVHTRGLDFACDIYIWAPLAGTGCVLLLSLVITLYCQRRKYRSNKGESPVEPAEPCRYSCPREEEGSTIPIQEDYRKPEPACSP (SEQ ID NO: 198) myc tag + CD8 TM sequence and CD30 IC signaling sequence:EQKLISEEDLAAATGTTTPAPRPPTPAPTIASOPLSLRPEACRPAAGGAVHTRGLDFACDIYIWAPLAGTGCVLLLSLVITLYCHRRACRKRIRQKLHLCYPVQTSQPKLELVDSRPRRSSTQLRSGASVTEPVAEERGLMSQPLMETCHSVGAAYLESLPLQDASPAGGPSSPRDLPEPRVSTEHTNNKIEKIYIMKADTVIVGTVKAELPEGRGLAGPAEPELEEELEADHTPHYPEQETEPPLGSCSDVMLSVEEEGKEDPLPTAASGK (SEQ ID NO: 199)CD8 TM sequence and CD30 IC signaling sequence:AAATGTTTPAPRPPTPAPTIASQPLSLRPEACRPAAGGAVHTRGLDFACDIYIWAPLAGTGCVLLLSLVITLYCHRRACRKRIRQKLHLCYPVQTSQPKLELVDSRPRRSSTQLRSGASVTEPVAEERGLMSQPLMETCHSVGAAYLESLPLQDASPAGGPSSPRDLPEPRVSTEHTNNKIEKIYIMKADTVIVGTVKAELPEGRGLAGPAEPELEEELEADHTPHYPEQETEPPLGSCSDVMLSVEEEGKEDPLPTAASGK (SEQ ID NO: 200) myc tag + CD8 TM sequence and 0X40 IC signaling sequence:EQKLISEEDLAAATGTTTPAPRPPTPAPTIASOPLSLRPEACRPAAGGAVHTRGLDFACDIYIWAPLAGTGCVLLLSLVITLYCALYLLRRDQRLPPDAHKPPGGGSFRTPIQEEQADAHSTLAKI (SEQ ID NO: 201)CD8 TM sequence and 0X40 IC signaling sequence:AAATGTTTPAPRPPTPAPTIASQPLSLRPEACRPAAGGAVHTRGLDFACDIYIWAPLAGTGCVLLLSLVITLYCALYLLRRDQRLPPDAHKPPGGGSFRTPIQEEQADAHSTLAKI (SEQID NO: 202) myc tag + CD8 TM sequence and 4-1BB IC signaling sequence:EQKLISEEDLAAATGTTTPAPRPPTPAPTIASOPLSLRPEACRPAAGGAVHTRGLDFACDIYIWAPLAGTGCVLLLSLVITLYCKRGRKKLLYIFKQPFMRPVQTTQEEDGCSCRFPEEEEGGCEL (SEQ ID NO: 203)CD8 TM sequence and 4-1BB IC signaling sequence:AAATGTTTPAPRPPTPAPTIASQPLSLRPEACRPAAGGAVHTRGLDFACDIYIWAPLAGTGCVLLLSLVITLYCKRGRKKLLYIFKQPFMRPVQTTQEEDGCSCRFPEEEEGGCEL (SEQID NO: 204)

[0287] In some embodiments, the CSR comprises an intracellular signaling domain of 4- IBB.In some embodiments, the CSR comprises an intracellular signaling domain of CD27. In someembodiments, the CSR comprises an intracellular signaling domain of CD28. In some embodiments, the CSR comprises an intracellular signaling domain of CD30. In some embodiments, the CSR comprises an intracellular signaling domain of 0X40. In some embodiments, the CSR comprises an intracellular signaling domain of ICOS. In some embodiments, the CSR comprises an intracellular signaling domain of DAP10. In some embodiments, the CSR comprises an intracellular signaling domain comprising the amino acid sequence of any one of SEQ ID NOs: 180-186.

[0288] In some embodiments, the transmembrane module of a CSR of the present disclosure comprises one or more transmembrane domains derived from, for example, CD28, CD3s, CD3(^, CD45, CD4, CD5, CD8, CD9, CD16, CD22, CD33, CD37, CD64, CD80, CD86, CD134, CD137, or CD154. In some embodiments, the CSR comprises a fragment of a transmembrane protein (fTMP), wherein the fTMP comprises the CSR transmembrane domain. Exemplary transmembrane domain (TM) sequences are provided below:CD8 TM sequence: IYIWAPLAGTCGVLLLSLVIT (SEQ ID NO: 205)4-1BB TM sequence: IISFFLALTSTALLFLLFFLTLRFSVV (SEQ ID NO: 206)CD27 TM sequence: IEVIFSGMFEVFTEAGAEFEH (SEQ ID NO: 207)CD28 TM sequence: FWVEVVVGGVEACYSEEVTVAFIIFWV (SEQ ID NO: 208)CD30 TM sequence: PVEDAGPVEFWVIEVEVVVVGSSAFEEC (SEQ ID NO: 209)0X40 TM sequence: VAAIEGEGEVEGEEGPEAIEE (SEQ ID NO: 210)ICOS TM sequence: FWEPIGCAAFVVCIEGCIEI (SEQ ID NO: 211)DAP10 TM sequence: EEAGEVAADAVASEEIVGAVFE (SEQ ID NO: 212)CD40 TM sequence: AEVVIPIIFGIEFAIEEVEVFI (SEQ ID NO: 213)

[0289] In some embodiments, the CSR comprises a transmembrane domain of CD8. In some embodiments, the CSR comprises a transmembrane domain of 4-1BB. In some embodiments, the CSR comprises a transmembrane domain of CD27. In some embodiments, the CSR comprises a transmembrane domain of CD28. In some embodiments, the CSR comprises a transmembrane domain of CD30. In some embodiments, the CSR comprises a transmembrane domain of 0X40. In some embodiments, the CSR comprises a transmembrane domain of ICOS. In some embodiments, the CSR comprises a transmembrane domain of DAP10. In some embodiments, the CSR comprises a transmembrane domain of CD40. In some embodiments, theCSR comprises a transmembrane domain comprising the amino acid sequence of any one of SEQ ID NOs: 205-213.

[0290] In some embodiments, the CSR comprises a transmembrane domain (e.g., CD8 transmembrane domain) and an intracellular signaling domain of CD27. In some embodiments, the CSR comprises a CD8 transmembrane domain and an intracellular signaling domain of CD30. In some embodiments, the CSR comprises a CD8 transmembrane domain and an intracellular signaling domain of 0X40. In some embodiments, the CSR comprises a CD8 transmembrane domain and an intracellular signaling domain of 4-1BB. In some embodiments, the CSR comprises a transmembrane domain and an intracellular signaling domain comprising the amino acid sequence of any one of SEQ ID NOs: 187-204.

[0291] In some embodiments, the CSR further comprises a spacer module between any of the antigen-binding module, the transmembrane module, and the co-stimulatory signaling module. In some embodiments, the spacer module comprises one or more peptide linkers connecting two CSR modules. In some embodiments, the spacer module comprises one or more peptide linkers between about 5 to about 70 (such as about any of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70, including any ranges between these values) amino acids in length.

[0292] In some embodiments, the target-binding module is an antibody moiety. In some embodiments, the antibody moiety is a Fab, a Fab’, a (Fab’ , an Fv, or an scFv. In some embodiments, the anti-MSEN antibody moiety comprises the CDRs or variables domains (Vn and / or VL) of an antibody moiety that specifically binds to an MSEN ECD, such as any of anti- MSLN antibody moieties described elsewhere herein. In some embodiments, the anti-MSLN CSR comprises the anti-MSLN antibody moiety of Clone A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, or A46. In some embodiments, the anti-MSLN CSR comprises an anti-MSLN antibody moiety comprising VH and VL comprising the amino acid sequence of SEQ ID NOs: 16 and 17, respectively, SEQ ID NOs: 32 and 33, respectively, SEQ ID NOs: 48 and 49, respectively, SEQ ID NOs: 64 and 65, respectively, SEQ ID NOs: 82 and 83, respectively, SEQ ID NOs: 98 and 99, respectively, SEQ ID NOs: 114 and 115, respectively, SEQ ID NOs: 130 and 131, respectively, SEQ ID NOs: 147 and 148, respectively, SEQ ID NOs: 163 and 164, respectively, SEQ ID NOs: 177 and 178, respectively, SEQ ID NOs: 361 and 362, respectively, or SEQ ID NOs: 375 and 376, respectively; or variants thereof having, individually, at least about 95% (for example at least about any of 96%, 97%, 98%, or 99%) sequence identity. In some embodiments, the anti-MSLN CSR comprises an anti-MSLN antibody moiety comprisingVH and VL comprising the amino acid sequence of SEQ ID NOs: 16 and 17, respectively, SEQ ID NOs: 32 and 33, respectively, SEQ ID NOs: 48 and 49, respectively, SEQ ID NOs: 64 and 65, respectively, SEQ ID NOs: 82 and 83, respectively, SEQ ID NOs: 98 and 99, respectively, SEQ ID NOs: 114 and 115, respectively, SEQ ID NOs: 130 and 131, respectively, SEQ ID NOs: 147 and 148, respectively, SEQ ID NOs: 163 and 164, respectively, SEQ ID NOs: 177 and 178, respectively, SEQ ID NOs: 361 and 362, respectively, or SEQ ID NOs: 375 and 376, respectively. In some embodiments, the anti-MSLN CSR comprises a single polypeptide chain comprising: a) any one of the anti-MSLN antibody moieties of Clone A05, A09, A10, A13, A14, A15, A16, A17, A24, A39, A44, A45, or A46; b) a transmembrane module; and c) a costimulatory signaling module.

[0293] The present disclosure also provides effector cells (such as T cells) that co-express a caTCR and a CSR or co-express a CAR and a CSR. Such effector cells are also referred to herein as “caTCR + CSR effector cells” or “CAR + CSR effector cells”, respectively. In some embodiments, the caTCR + CSR effector cell (such as a T cell) comprises a nucleic acid sequence encoding the CSR operably linked to an inducible promoter, including any of the inducible promoters described herein. In some embodiments, the expression of the CSR in the caTCR + CSR effector cell (such as a T cell) is inducible upon signaling through the caTCR. In some such embodiments, the caTCR + CSR effector cell (such as a T cell) comprises a nucleic acid sequence encoding the CSR operably linked to a promoter or regulatory element that is responsive to signaling through the caTCR. In some embodiments, the nucleic acid sequence encoding the CSR is operably linked to a nuclear-factor of the activated T-cell (NFAT)-derived promoter. In some embodiments, the NFAT-derived promoter is an NFAT-derived minimal promoter (see for example Durand, D. et. al., Molec. Cell. Biol. 8, 1715-1724 (1988); Clipstone, NA, Crabtree, GR. Nature 357(6380): 695-7(1992); Chmielewski, M., et al. Cancer research 71.17 (2011): 5697-5706; and Zhang, L„ et al. Molecular therapy 19 (4): 751-759 (2011)). Further description of CSRs may be found in US Application No. 62 / 490,578, filed April 26, 2017, and WO2018 / 200583, which are incorporated by reference herein in their entirety.

[0294] The present disclosure also provides effector cells (such as T cells) that express a caTCR or a CAR and anti-MSLN CSR (such as an anti-MSLN CSR described herein). Such effector cells are also referred to herein as “caTCR + anti-MSLN CSR effector cells” or “CAR + anti-MSLN CSR effector cells.” In some embodiments, the caTCR + anti-MSLN CSR effector cell or CAR + anti-MSLN CSR effector cell (such as a T cell) comprises a nucleic acid sequenceencoding the anti-MSLN CSR operably linked to an inducible promoter, including any of the inducible promoters described herein. In some embodiments, the expression of the anti-MSLN CSR in the caTCR + anti-MSLN CSR effector cell (such as a T cell) or expression of the anti- MSLN CSR in the CAR + anti-MSLN CSR effector cell (such as a T cell) is inducible upon signaling through the caTCR or CAR, respectively. In some such embodiments, the caTCR + anti-MSLN CSR effector cell (such as a T cell) the CAR + anti-MSLN CSR effector cell (such as a T cell) comprises a nucleic acid sequence encoding the anti-MSLN CSR operably linked to a promoter or regulatory element that is responsive to signaling through the caTCR or CAR, respectively. In some embodiments, the nucleic acid sequence encoding the anti-MSLN CSR is operably linked to a nuclear-factor of the activated T-cell (NFAT)-derived promoter. In some embodiments, the caTCR or CAR expressed by the caTCR or CAR + anti-MSLN CSR effector cell (such as a T cell) is an anti-MSLN caTCR or an anti-MSLN CAR, respectively. In some embodiments, the caTCR or CAR expressed by the caTCR or CAR + anti-MSLN CSR effector cell (such as a T cell) is not an anti-MSLN caTCR or CAR, respectively, and targets a different antigen.

[0295] In some embodiments, the CSR comprises a target-binding domain (e.g., an antibody moiety) that specifically binds an MSLN. In some embodiments, the CSR comprises a targetbinding domain (e.g., an antibody moiety) that does not specifically bind an MSLN. In some embodiments, the CSR comprises two or more target-binding domains (e.g., antibody moieties) that specifically bind to the same or different targets. In some embodiments, the CSR is monospecific. In some embodiments, the CSR is multi specific, such as bispecific.

[0296] In some embodiments, the target-binding domain is an antibody moiety, such as a Fab, a Fab’, a (Fab’ , an Fv, or an scFv. In some embodiments, the target-binding domain is an extracellular domain of a receptor or a ligand. In some embodiments, the target-binding domain is monospecific. In some embodiments, the target-binding domain is multispecific, e.g., bispecific. In some embodiments, the target-binding domain specifically binds an MSLN ECD. In some embodiments, the target-binding domain specifically binds an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the target-binding domain specifically binds a cell-surface antigen. In some embodiments, the target-binding domain specifically binds an antigenic peptide / MHC class I complex.

[0297] In some embodiments, the target-binding domain specifically binds a target expressed or present on a cancer cell. In some embodiments, the target-binding domain specifically binds atarget expressed or present on a mesothelioma, epithelioid mesothelioma, malignant pleural mesothelioma, pancreatic cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, ovarian cancer, ovarian serous adenocarcinoma, endometrial cancer, cervical cancer, lung adenocarcinoma, non- small cell lung cancer, AML / CLL, melanoma, gastrointestinal cancer, breast cancers (including metastatic breast cancer), glioma, prostate cancer, or a biliary cancer cell. In some embodiments, the target-binding domain specifically binds an MSLN ECD. In some embodiments, the anti-MSLN CSR comprises a first target-binding domain that specifically binds an MSLN ECD (e.g., an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2) and a second target-binding domain that specifically binds to a different region of the MSLN ECD than the region of the MSLN ECD that is specifically bound by the first target-binding domain. In some embodiments, the second target-binding domain specifically binds to the same region of the MSLN ECD as the region of the MSLN ECD that is specifically bound by the first target-binding domain, but specifically binds an epitope that is nonoverlapping with the epitope specifically bound by the first target-binding domain. In some embodiments, the anti-MSLN CSR comprises a first target-binding domain that specifically binds an MSLN ECD and a second target-binding domain that specifically binds a different target (e.g., a non-MSLN-ECD target). In some embodiments, the anti-MSLN CSR comprises a first target-binding domain that specifically binds an MSLN ECD and a second target-binding domain that specifically binds a cell-surface antigen. In some embodiments, the anti-MSLN CSR comprises a second target-binding domain that specifically binds an MSLN ECD and a first target-binding domain that specifically binds a cell-surface antigen. In some embodiments, the cell-surface antigen is selected from the group consisting of ROR1, ROR2, EpCAM, MUC1, MUC16, ERa, RORA, EGER, GPRC5D, GPC3, HER2, HER3, DLL3, c-Met, BCMA, CD19, CD22, EGFRvIII, PSMA, and p53. In some embodiments, the anti-MSLN CSR comprises a first target-binding domain that specifically binds an MSLN ECD and a second target-binding domain that specifically binds an antigenic peptide / MHC class I complex. In some embodiments, the anti-MSLN CSR comprises a second target-binding domain that specifically binds an MSLN ECD and a first target-binding domain that specifically binds an antigenic peptide / MHC class I complex. In some embodiments, the antigenic peptide is derived from a protein selected from the group consisting of MSLN, WT1, NDC80, KRAS, AFP, NY-ESO-1, HPV16-E7, PRAME, PSA, and Histone H3.3.Ill

[0298] In some embodiments, the anti-MSLN CSR is a bispecific anti-MSLN CSR. In some embodiments, the bispecific anti-MSLN CSR specifically binds an MSLN ECD, such as an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2, and at least one other target. In some embodiments, the bispecific anti-MSLN CSR comprises an anti-MSLN antibody moiety, such as any of the anti-MSLN antibody moieties provided herein, and an antibody moiety that specifically binds to the at least one other target. In some embodiments, the at least one other target is a different region of an MSLN ECD, such as an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2. In some embodiments, the at least one other target is the same region of an MSLN ECD, such as an MSLN ECD comprising the amino acid sequence of SEQ ID NO: 2, but a non-overlapping epitope. In some embodiments, the at least one other target is not an MSLN ECD (e.g., a non-MSLN-ECD target). In some embodiments, the at least one other target is expressed on a cancer cell. In some embodiments, the at least one other target is expressed on a mesothelioma, epithelioid mesothelioma, malignant pleural mesothelioma, pancreatic cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, ovarian cancer, ovarian serous adenocarcinoma, endometrial cancer, cervical cancer, lung adenocarcinoma, non- small cell lung cancer, AML, CLL, melanoma, gastrointestinal cancer, breast cancer (including metastatic breast cancer), glioma, prostate cancer, or a biliary cancer cell. In some embodiments, the at least one other target is a cell-surface antigen. In some embodiments, the cell-surface antigen is ROR1, ROR2, EpCAM, MUC1, MUC16, FRa, RORA, EGFR, GPRC5D, GPC3, HER2, HER3, DLL3, c-Met, BCMA, CD19, CD22, EGFRvIII, PSMA, or p53. In some embodiments, the at least one other target is a complex comprising an antigenic peptide and an MHC class I protein (an antigenic peptide / MHC class I complex). In some embodiments, the antigenic peptide is derived from MSLN, WT1, NDC80, KRAS, AFP, NY-ESO-1, HPV16-E7, PRAME, PSA, or Histone H3.3.Construct Combinations

[0299] In some aspects, provided herein are construct combinations that comprise at least two different constructs described herein. In some embodiments, at least one of the constructs is an anti-MSLN construct described herein, comprising an anti-MSLN antibody moiety (such as any one of the anti-MSLN antibody moieties described in the “Anti-MSLN Antibody Moieties” section). In some embodiments, the at least two different constructs are the same format, e.g., at least two different antibodies e.g., two different full-length IgG antibodies or two differentbispecific antibodies), at least two different CARs, or at least two different caTCRs. In some embodiments, the at least two different constructs are different formats, e.g., an antibody and a CAR; an antibody and a caTCR; a CAR and a CSR; a caTCR and a CSR; a CSR and a TCR, etc.

[0300] Also provided are construct combinations that comprise at least two different anti- MSLN constructs described herein, comprising an anti-MSLN antibody moiety (such as any one of the anti-MSLN antibody moieties described in the “Anti-MSLN Antibody Moieties” section). In some embodiments, the at least two different anti-MSLN constructs are the same format, e.g., at least two different antibodies (e.g., two different full-length IgG antibodies or two different bispecific antibodies), at least two different CARs, at least two different caTCRs, or at least two different CSRs. In some embodiments, the at least two different anti-MSLN constructs are different formats, e.g., an antibody and a CAR; an antibody and a caTCR; a CAR and a CSR; a caTCR and a CSR; a CSR and a TCR, etc.

[0301] In some embodiments, the caTCR, CAR or TCR and the CSR of an anti-MSLN construct combination provided herein are encoded on separate nucleic acids. In some embodiments, the separate nucleic acids are each expressed (e.g., separately) and translated (e.g., separately) in a cell (such as an anti-MSLN effector cell, which is described in further detail elsewhere herein). In some embodiments, the caTCR, CAR or TCR and the CSR of an anti- MSLN construct combination provided herein are encoded on the same nucleic acid (e.g., a single nucleic acid). In some embodiments, the single nucleic acid encoding the caTCR, CAR or TCR and CSR construct combination is expressed and translated to generate a single polypeptide which is subsequently processed (e.g., such as cleaved during or following translation) into separate polypeptides, e.g., the caTCR, CAR or TCR polypeptide(s) and CSR polypeptide.

[0302] In some embodiments, a single nucleic acid encoding a caTCR, CAR, or TCR and a CSR construct combination expresses a polypeptide comprising (from N-terminus to C- terminus) the amino acid sequence(s) of a caTCR, CAR or TCR construct, a peptide linker, and the amino acid sequence of a CSR construct. In some embodiments, a single nucleic acid encoding a caTCR, CAR or TCR and a CSR construct combination expresses a polypeptide comprising (from N-terminus to C-terminus) the amino acid sequence of a CSR construct, a peptide linker, and the amino acid sequence(s) of a caTCR, CAR or TCR construct. In some embodiments, the nucleic acid further encodes, e.g., one or more peptide linkers, peptide spacers, peptide tags, signal peptides and / or other amino acid sequences (see, e.g., Tables 6A and 6B for exemplary linker sequences and tag sequences).

[0303] In some embodiments, the anti-MSLN construct combination comprises an anti-MSLN construct (e.g., a construct that specifically binds an MSLN ECD, such as an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2) and a second construct that binds to a different region of the MSLN ECD than the region of the MSLN ECD that is specifically bound by the anti-MSLN construct. In some embodiments, the anti-MSLN construct combination comprises an anti-MSLN construct (e.g., a construct that specifically binds an MSLN ECD, such as an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2) and a second construct that binds to the same region of the MSLN ECD as the region of the MSLN ECD that is specifically bound by the anti-MSLN construct, but binds an epitope that is non-overlapping with the epitope specifically bound by the anti-MSLN construct. In embodiments, the anti- MSLN construct combination comprises an anti-MSLN construct (e.g., a construct that specifically binds an MSLN ECD, such as an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2) and a second construct that binds to a target that is not an MSLN (e.g., a non-MSLN-ECD target).

[0304] In some embodiments, the anti-MSLN construct combination comprises anti-MSLN CAR (e.g., a CAR that specifically binds an MSLN ECD, such as an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2) and a CSR that binds to a different region of the MSLN ECD than the region of the MSLN ECD that is specifically bound by the anti-MSLN CAR. In some embodiments, the anti-MSLN construct combination comprises anti-MSLN CAR and a CSR that binds to the same region of the MSLN ECD as the region of the MSLN ECD that is specifically bound by the anti-MSLN CAR, but binds an epitope that is non-overlapping with the epitope specifically bound by the anti-MSLN CAR. In some embodiments, the anti-MSLN construct combination comprises anti-MSLN CAR and a CSR that binds to a non-MSLN-ECD target.

[0305] In some embodiments, the anti-MSLN construct combination comprises anti-MSLN caTCR (e.g., a caTCR that specifically binds an MSLN ECD, such as an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2) and a CSR that binds to a different region of the MSLN ECD than the region of the MSLN ECD that is specifically bound by the anti- MSLN caTCR. In some embodiments, the anti-MSLN construct combination comprises anti- MSLN caTCR and a CSR that binds to the same region of the MSLN ECD as the region of the MSLN ECD that is specifically bound by the anti-MSLN caTCR, but binds an epitope that is non-overlapping with the epitope specifically bound by the anti-MSLN caTCR. In someembodiments, the anti-MSLN construct combination comprises anti-MSLN caTCR and a CSR that binds to a non-MSLN-ECD target.

[0306] In some embodiments, the anti-MSLN construct combination comprises anti-MSLN CSR (e.g., a CSR that specifically binds an MSLN ECD, such as an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2) and a CAR that binds to a different region of the MSLN ECD than the region of the MSLN ECD that is specifically bound by the anti-MSLN CSR. In some embodiments, the anti-MSLN construct combination comprises anti-MSLN CSR and a CAR that binds to the same region of the MSLN ECD as the region of the MSLN ECD that is specifically bound by the anti-MSLN CSR, but binds an epitope that is non-overlapping with the epitope specifically bound by the anti-MSLN CSR. In some embodiments, the anti- MSLN construct combination comprises anti-MSLN CSR and a CAR that binds to a non- MSLN-ECD target.

[0307] In some embodiments, the anti-MSLN construct combination comprises anti-MSLN CSR (e.g., a CSR that specifically binds an MSLN ECD, such as an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2) and a caTCR that binds to a different region of the MSLN ECD than the region of the MSLN ECD that is specifically bound by the anti-MSLN CSR. In some embodiments, the anti-MSLN construct combination comprises anti-MSLN CSR and a caTCR that binds to the same region of the MSLN ECD as the region of the MSLN ECD that is specifically bound by the anti-MSLN CSR, but binds an epitope that is non-overlapping with the epitope specifically bound by the anti-MSLN CSR. In some embodiments, the anti- MSLN construct combination comprises anti-MSLN CSR and a caTCR that binds to a non- MSLN-ECD target.

[0308] In some embodiments, the anti-MSLN construct combination comprises anti-MSLN CSR (e.g., a CSR that specifically binds an MSLN ECD, such as an MSLN ECD that comprises the amino acid sequence of SEQ ID NO: 2) and a TCR that binds to a non-MSLN-ECD target.

[0309] In some embodiments, the anti-MSLN construct combination comprises an anti-MSLN construct that specifically binds an MSLN ECD and a CSR or bispecific CSR, the caTCR or bispecific caTCR, or the CAR or bispecific CAR that comprises a target-binding domain that binds to target that is not an MSLN (e.g., a non-MSLN-ECD target). In some embodiments, the non-MSLN-ECD target is a cell-surface antigen. In some embodiments, the CSR or bispecific CSR, the caTCR or bispecific caTCR, or the CAR or bispecific CAR comprises a non-MSLN- binding domain that is a cell-surface antigen-binding module selected from the group consistingof: (i) a RORl-binding module (e.g., an anti-RORl antibody moiety), (ii) a ROR2-binding module (e.g., an anti-ROR2 antibody moiety), (iii) a EpCAM-binding module (e.g., an anti- EpCAM antibody moiety), (iv) a MUCl-binding module (e.g., an anti-MUCl antibody moiety), (v) a MUC16-binding module (e.g., an anti-MUC16 antibody moiety), (vi) a FRa-binding module (e.g., an anti-FRa antibody moiety), (vii) a RORA-binding module (e.g., an anti-RORA antibody moiety), (viii) a EGFR-binding module (e.g., an anti-EGFR antibody moiety), (ix) a GPRC5D-binding module (e.g., an anti-GPRC5D antibody moiety), (x) a GPC3-binding module (e.g., an anti-GPC3 antibody moiety), (xi) a HER2-binding module (e.g., an anti-HER2 antibody moiety), (xii) a HER3-binding module (e.g., an anti-HER3 antibody moiety), (xiii) a DLL3- binding module (e.g., an anti-DLL3 antibody moiety), (xiv) a cMet-binding module (e.g., an anti-cMet antibody moiety), (xv) a BCMA-binding module (e.g., an anti-BCMA antibody moiety), (xvi) a CD19-binding module (e.g., an anti-CD19 antibody moiety), (xvii) a CD22- binding module (e.g., an anti-CD22 antibody moiety), (xviii) a EGFRvIII-binding module (e.g., an anti-EGFRvIII antibody moiety), (xix) a PSMA-binding module (e.g., an anti-PSMA antibody moiety), and (xx) a p53-binding module (e.g., an anti-p53 antibody moiety). In some embodiments, the non-MSLN-ECD target is expressed on a cancer cell. In some embodiments, the non-MSLN-ECD target is expressed on a mesothelioma, epithelioid mesothelioma, malignant pleural mesothelioma, pancreatic cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, ovarian cancer, ovarian serous adenocarcinoma, endometrial cancer, cervical cancer, lung adenocarcinoma, non-small cell lung cancer, AML, CLL, melanoma, gastrointestinal cancer, breast cancer (including metastatic breast cancer), glioma, prostate cancer, or a biliary cancer cell.

[0310] In some embodiments, the anti-MSLN construct combination comprises an anti-MSLN construct that specifically binds an MSLN ECD and a CSR or bispecific CSR, a caTCR or bispecific caTCR, or a CAR or bispecific CAR that comprises a non-MSLN-ECD-binding module that is an anti-RORl -binding module (e.g., an anti-RORl antibody moiety) that specifically binds ROR1. In some embodiments, the anti-RORl antibody moiety comprises an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a VH comprising the amino acid sequence of SEQ ID NO: 260, and an LC-CDR1, an LC-CDR2, and an LC-CDR3 of a VL comprising the amino acid sequence of SEQ ID NO: 261. In some embodiments, the anti-RORl antibody moiety comprises a VH comprising the amino acid sequence of SEQ ID NO: 260, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 81%, 82%, 83%, 84%,85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 260, and a VL comprising the amino acid sequence of SEQ ID NO: 261, or a variant thereof having at least about 80% (e.g., at least about any one of 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) sequence identity to the amino acid sequence of SEQ ID NO: 261. In some embodiments, the anti-RORl antibody moiety comprises the amino acid sequence of SEQ ID NO: 259, or a variant thereof comprising at least about 80% sequence identity (e.g., at least about any one of 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) to the amino acid sequence of SEQ ID NO: 259. Additional anti-RORl antibody ...

Claims

CLAIMSWhat is claimed is:

1. An anti-MSLN construct comprising an antibody moiety that specifically binds to a mesothelin (MSLN) extracellular domain (ECD) (anti-MSLN antibody moiety), wherein the anti-MSLN antibody moiety comprises:(i) a heavy chain variable domain (VH) comprising a heavy chain complementarity determining region (HC-CDR) 1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 16, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR 1, HC-CDR2, and HC-CDR3 of the reference VH, and a light chain variable domain (VL) comprising a light chain complementarity determining region (LC- CDR) 1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 17, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(ii) a VH comprising an HC-CDR 1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 32, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR 1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 33, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(iii) a VH comprising an HC-CDR 1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 48, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR 1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 49, or a variant thereof comprising up to (1) three aminoacid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(iv) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 64, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 65, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(v) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 82, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 83, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(vi) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 98, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 99, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(vii) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 114, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 115, or a variant thereof comprising up to (1) three aminoacid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(viii) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 130, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 131, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(ix) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 147, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 148, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(X) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 163, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 164, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(xi) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 177, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 178, or a variant thereof comprising up to (1) three aminoacid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL;(xii) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 361, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 362, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL; or(xiii) a VH comprising an HC-CDR1, an HC-CDR2, and an HC-CDR3 of a reference VH comprising the amino acid sequence of SEQ ID NO: 375, or a variant thereof comprising up to three amino acid substitutions in each of one, two, or all of the HC- CDR1, HC-CDR2, and HC-CDR3 of the reference VH, and a VL comprising an LC- CDR1, an LC-CDR2, and an LC-CDR3 of a reference VL comprising the amino acid sequence of SEQ ID NO: 376, or a variant thereof comprising up to (1) three amino acid substitutions in one or both of the LC-CDR1 and LC-CDR3 of the reference VL, and / or (2) two amino acid substitutions in the LC-CDR2 of the reference VL.

2. The anti-MSLN construct of claim 1, wherein the MSLN ECD comprises the amino acid sequence of SEQ ID NO: 2.

3. The anti-MSLN construct of claim 1 or 2, wherein the anti-MSLN antibody moiety comprises:1) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 4, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 5; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 6, an LC-CDR2 comprising the amino acid sequence of GAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 7;2) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 19, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 20, andan HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 21; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 22, an LC-CDR2 comprising the amino acid sequence of GNN, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 23;3) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 35, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 36, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 37; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 38, an LC-CDR2 comprising the amino acid sequence of RNN, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 39;4) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 52, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 53; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 54, an LC-CDR2 comprising the amino acid sequence of STT, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 55;5) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 69, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 71; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 72, an LC-CDR2 comprising the amino acid sequence of DAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 73;6) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 85, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 86, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 87; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 88, an LC-CDR2 comprising the amino acid sequence of RNN, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 89;7) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 69, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 70, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 103; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 104,an LC-CDR2 comprising the amino acid sequence of SAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 105;8) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 117, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 118, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 119; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 120, an LC-CDR2 comprising the amino acid sequence of HNS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 121;9) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 134, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 135, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 136; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, an LC-CDR2 comprising the amino acid sequence of GAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 138;10) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 150, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 151, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 152; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, an LC-CDR2 comprising the amino acid sequence of AAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 154;11) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 166, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 167; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, an LC-CDR2 comprising the amino acid sequence of AAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 168;12) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 242, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 102, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 153; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 137, an LC-CDR2 comprising the amino acid sequence of AAS, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 244; or13) i) a VH comprising an HC-CDR1 comprising the amino acid sequence of SEQ ID NO: 51, an HC-CDR2 comprising the amino acid sequence of SEQ ID NO: 52, and an HC-CDR3 comprising the amino acid sequence of SEQ ID NO: 364; and ii) a VL comprising an LC-CDR1 comprising the amino acid sequence of SEQ ID NO: 365, an LC-CDR2 comprising the amino acid sequence of NNN, and an LC-CDR3 comprising the amino acid sequence of SEQ ID NO: 366.

4. The anti-MSLN construct of any one of claims 1-3, wherein the anti-MSLN antibody moiety comprises:1) i) a VH comprising the amino acid sequence of SEQ ID NO: 16, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 16; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 17, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 17;2) i) a VH comprising the amino acid sequence of SEQ ID NO: 32, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 32; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 33, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 33;3) i) a VH comprising the amino acid sequence of SEQ ID NO: 48, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 48; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 49, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 49;4) i) a VH comprising the amino acid sequence of SEQ ID NO: 64, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 64; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 65, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 65;5) i) a VH comprising the amino acid sequence of SEQ ID NO: 82, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 82; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 83, or avariant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 83;6) i) a VH comprising the amino acid sequence of SEQ ID NO: 98, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 98; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 99, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 99;7) i) a VH comprising the amino acid sequence of SEQ ID NO: 114, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 114; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 115, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 115;8) i) a VH comprising the amino acid sequence of SEQ ID NO: 130, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 130; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 131, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 131;9) i) a VH comprising the amino acid sequence of SEQ ID NO: 147, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 147; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 148, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 148;10) i) a VH comprising the amino acid sequence of SEQ ID NO: 163, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 163; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 164, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 164;11) i) a VH comprising the amino acid sequence of SEQ ID NO: 177, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 177; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 178, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 178;12) i) a VH comprising the amino acid sequence of SEQ ID NO: 361, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 361; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 362, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 362; or13) i) a VH comprising the amino acid sequence of SEQ ID NO: 375, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 375; and ii) a VL comprising the amino acid sequence of SEQ ID NO: 376, or a variant thereof having at least about 80% sequence identity to the amino acid sequence of SEQ ID NO: 376.

5. The anti-MSLN construct of any one of claims 1-4, wherein the anti-MSLN antibody moiety is a full-length antibody, a Fab, a Fab’, a F(ab’)2, an Fv, or a single chain Fv (scFv).

6. The anti-MSLN construct of claim 5, wherein the anti-MSLN antibody moiety is an scFv that comprises the amino acid sequence of any one of SEQ ID NOs: 18, 34, 50, 66, 84, 100, 101, 116, 132, 149, 165, 363, and 377.

7. The anti-MSLN construct of any one of claims 1-6, wherein the anti-MSLN construct is an anti-MSLN chimeric antigen receptor (CAR) comprising:(a) an extracellular domain comprising the anti-MSLN antibody moiety;(b) a transmembrane domain; and(c) an intracellular signaling domain.

8. The anti-MSLN construct of claim 7, wherein:(i) the intracellular signaling domain comprises a primary immune cell signaling sequence derived from CD3^, TCR^, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, or CD66d; and / or(ii) the intracellular signaling domain further comprises a costimulatory signaling sequence derived from CD28, CD30, 4- IBB, DAP10, ICOS, or 0X40.

9. The anti-MSLN construct of any one of claims 1-6, wherein the anti-MSLN construct is an anti-MSLN chimeric antibody-T cell receptor (TCR) construct (caTCR) comprising:(a) an extracellular domain comprising the anti-MSLN antibody moiety; and(b) a TCR module (TCRM), wherein the TCRM comprises a first TCR domain (TCRD) comprising a first TCR transmembrane domain (TCR-TM) and a second TCRD comprising a second TCR-TM, wherein the TCRM is capable of associating with at least one TCR-associated signaling molecule.

10. The anti-MSLN construct of claim 9, wherein:(i) the first TCR-TM is derived from one of the transmembrane domains of a naturally occurring TCR and the second TCR-TM is derived from the other transmembrane domain of the naturally occurring TCR; and / or(ii) the at least one TCR-associated signaling molecule is selected from the group consisting of CD35s, CD3ys, and ( .

11. The anti-MSLN construct of claim 9 or 10, wherein:(a) (i) the first TCR-TM is derived from TCRy, and the second TCR-TM is derived from TCR5; or(ii) the second TCR-TM is derived from TCRy, and the first TCR-TM is derived from TCR5; or(b) (i) the first TCR-TM is derived from TCRa, and the second TCR-TM is derived from TCRP; or(ii) the second TCR-TM is derived from TCRa, and the first TCR-TM is derived from TCRp.

12. The anti-MSLN construct of any one of claims 1-6, wherein the construct is an anti- MSLN chimeric signaling receptor (CSR) comprising:(a) a target-binding module comprising the anti-MSLN antibody moiety;(b) a transmembrane module; and(c) a co- stimulatory immune cell signaling module that is capable of providing a costimulatory signal to an effector cell; andwherein the CSR lacks a functional primary immune cell signaling domain; optionally wherein the functional primary immune cell signaling domain is derived from a TCR-associated T cell activation molecule selected from the group consisting of CD3^ (TCRQ, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, and CD66d.

13. The anti-MSLN construct of claim 12, wherein:(i) the transmembrane module of the anti-MSLN CSR comprises one or more transmembrane domains derived from CD28, CD30, CD3s, CD3(^, CD45, CD4, CD5, CD8, CD9, CD16, CD22, CD27, CD33, CD37, CD64, CD80, CD86, 0X40 (CD134), 4-1BB (CD137), CD154, or ICOS; and / or(ii) the co- stimulatory immune cell signaling module of the anti-MSLN CSR is derived from the intracellular domain of a co- stimulatory receptor of a TCR, optionally wherein the co-stimulatory receptor is selected from the group consisting of CD28, 4- 1BB, 0X40, ICOS, CD27, CD30, CD40, and DAP10.

14. The anti-MSLN construct of any one of claims 1-6, wherein the anti-MSLN construct is an anti-MSLN immunoconjugate comprising the anti-MSLN antibody moiety and an effector molecule, wherein the effector molecule is:(i) a therapeutic agent selected from the group consisting of a drug, a toxin, a radioisotope, a protein, a peptide, and a nucleic acid; or(ii) a detectable label.

15. The anti-MSLN construct of any one of claims 1-14, wherein the anti-MSLN construct further comprises at least one other antibody moiety that specifically binds to at least one other target which is not MSLN ECD.

16. The anti-MSLN construct of claim 15, wherein the at least one other target is:(i) a cell-surface antigen selected from the group consisting of R0R1, R0R2, EpCAM, MUC1, MUC16, FRa, RORA, EGFR, GPRC5D, GPC3, HER2, HER3, DLL3, c- Met, BCMA, CD19, CD22, EGFRvIII, PSMA, and p53; or(ii) a complex comprising an antigenic peptide and a major histocompatibility (MHC) class I protein (an antigenic peptide / MHC class I complex), wherein the antigenicpeptide is derived from a protein selected from the group consisting of MSLN, WT1, NDC80, KRAS, AFP, NY-ESO-1, HPV16-E7, PRAME, PSA, and Histone H3.3.

17. An isolated nucleic acid or a set of isolated nucleic acids encoding the polypeptide component(s) of the anti-MSLN construct of any one of claims 1-16.

18. A host cell comprising the anti-MSLN construct of any one of claims 1-16 or the nucleic acid(s) of claim 17.

19. A method of producing the anti-MSLN construct of any one of claims 1-16, comprising culturing the host cell of claim 18 under a condition where the anti-MSLN construct is expressed, and recovering the anti-MSLN construct produced by the host cell.

20. An effector cell expressing the anti-MSLN construct of any one of claims 1-16.

21. An effector cell expressing the anti-MSLN CSR of any one of claims 12-13, 15, and 16, wherein the effector cell further expresses:(i) a CAR comprising:(a) an extracellular domain that specifically binds to a target;(b) a transmembrane domain; and(c) an intracellular signaling domain; or(ii) a caTCR comprising:(a) an extracellular domain that specifically binds to a target; and(b) a TCRM, wherein the TCRM comprises a first TCRD comprising a first TCR-TM and a second TCRD comprising a second TCR-TM, wherein the TCRM is capable of associating with at least one TCR-associated signaling molecule.

22. The effector cell of claim 21, wherein:(a) (i) the CAR is an anti-MSLN CAR that specifically binds an MSLN ECD target; or (ii) the caTCR is an anti-MSLN caTCR that specifically binds an MSLN ECD target; or(b) the CAR or caTCR specifically binds a target that is not an MSLN ECD.

23. An effector cell expressing the anti-MSLN CSR of any one of claims 12-13, 15, and 16, wherein the effector cell further expresses a TCR that specifically binds to a target, and wherein the target is an antigenic peptide / MHC class I complex.

24. An effector cell expressing the anti-MSLN CAR of any one of claims 7-8, 15, and 16, or the anti-MSLN caTCR of any one of claims 9-11, 15, and 16, wherein the effector cell further expresses a CSR comprising:(i) a target-binding domain that specifically binds a target;(ii) a transmembrane module; and(iii) a co-stimulatory immune cell signaling module that is capable of providing a costimulatory signal to the effector cell, wherein the target-binding domain and the co-stimulatory immune cell signaling module are not derived from the same molecule, and wherein the CSR lacks a functional primary immune cell signaling domain; optionally wherein the functional primary immune cell signaling domain is derived from a TCR-associated T cell activation molecule selected from the group consisting of CD3^ (TCRQ, FcRy, FcRp, CD3y, CD35, CD3s, CD5, CD79a, CD79b, and CD66d.

25. The effector cell of claim 24, wherein:(i) the CSR is an anti-MSLN CSR that specifically binds an MSLN ECD target; or(ii) the CSR specifically binds a target that is not an MSLN ECD.

26. The effector cell of claim 22 or 25, wherein the target is:(i) a cell-surface antigen selected from the group consisting of R0R1, R0R2, EpCAM, MUC1, MUC16, FRa, RORA, EGFR, GPRC5D, GPC3, HER2, HER3, DLL3, c- Met, BCMA, CD19, CD22, EGFRvIII, PSMA, and p53; or(ii) an antigenic peptide / MHC class I complex, and wherein the antigenic peptide is derived from a protein selected from the group consisting of MSLN, WT1, NDC80, KRAS, AFP, NY-ESO-1, HPV16-E7, PRAME, PSA, and Histone H3.3.

27. The effector cell of any one of claims 20-26, wherein the effector cell is an immune cell, optionally wherein the immune cell is a T cell or a NK cell.

28. A pharmaceutical composition comprising the anti-MSLN construct of any one of claims 1-16, the nucleic acid(s) of claim 17, the host cell of claim 18, or the effector cell of any one of claims 20-27, and a pharmaceutical acceptable carrier.

29. A method of detecting MSLN in a sample, comprising contacting the sample with the anti-MSLN construct of claim 14 wherein the effector molecule is a detectable label, and detecting the presence of the label.

30. A method of treating an individual having a disease or disorder associated with aberrant expression of MSLN, comprising administering to the individual an effective amount of the anti- MSLN construct of any one of claims 1-16, the nucleic acid(s) of claim 17, the host cell of claim 18, the effector cell of any one of claims 20-27, or the pharmaceutical composition of claim 28.

31. A method of diagnosing an individual having a disease or disorder associated with aberrant expression of MSLN, comprising:(i) (a) administering an effective amount of the anti-MSLN construct of claim 14 to the individual, wherein the effector molecule is a detectable label; and(b) determining the level of the label in the individual, wherein a level of the label above a threshold level indicates that the individual has the disease or disorder associated with aberrant expression of MSLN; or(ii) (a) contacting a sample derived from the individual with the anti-MSLN construct of claim 14, wherein the effector molecule is a detectable label; and(b) determining the number of cells bound with the anti-MSLN construct in the sample, wherein a value for the number of cells bound with the anti-MSLN construct above a threshold level indicates that the individual has the disease or disorder associated with aberrant expression of MSLN.

32. The method of claim 30 or 31, wherein the disease or disorder associated with aberrant expression of MSLN is cancer.

33. A method of killing a target cell that expresses MSLN, the method comprising contacting the target cell with an effective amount of the anti-MSLN construct of any one of claims 1-16, the nucleic acid(s) of claim 17, the host cell of claim 18, the effector cell of any one of claims 20-27, or the pharmaceutical composition of claim 28.

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