Monoclonal antibodies against CD303 and methods of use thereof

Abstract

The present disclosure relates to monoclonal antibodies or a fragment thereof that specifically bind to CD303 (BDCA2), chimeric antigen receptor (CAR) targeting CD303 and dual chimeric antigen receptor (CAR) including a first CAR and a second CAR. In some embodiments, the present disclosure provides a method of treating a disorder associated with plasmacytoid dendritic cells (pDC) in a subject in need thereof, wherein the method includes delivering to the subject a therapeutically effective amount of an antibody targeting CD303, a CAR targeting CD303, or a dual CAR targeting CD303.

Description

PATENT DOCKET NO. MDA1380-1WOMONOCLONAL ANTIBODIES AGAINST CD303 AND METHODS OF USE THEREOFCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of priority under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 63 / 790,531, filed April 17, 2025. The disclosure of the prior application is considered part of and is herein incorporated by reference in the disclosure of this application in its entirety.INCORPORATION OF SEQUENCE LISTING

[0002] The material in the accompanying sequence listing is hereby incorporated by reference into this application. The accompanying sequence listing xml file, named MDA1380-lWO.xml, was created on April 7, 2026, and is 21,350 bytes.BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

[0003] The present invention relates generally to targeting the CD303 receptor, and more specifically to antibodies and chimeric antigen receptors (CARs) targeting CD303 for the treatment of disorders associated with CD303 expression.BACKGROUND INFORMATION

[0004] CD303 (BDCA-2-blood dendritic cells antigen 2 / CLEC4C, C-type lectin domain family 4, member C), is a type II receptor unique to human plasmacytoid DC (pDCs), main producers of type-I interferons in the organism. CD303 works alongside TLR-7 / 9 in recognizing microbes and coordinating inflammatory immune responses. Clinical implications of pDCs in various malignancies, include infiltration of pDCs (CD303+) into metastatic lymph nodes in breast cancer, mucosa of oral squamous cell carcinoma and tissues surrounding malignant cells in non-small-cell lung cancer, etc. CD303+ pDCs has also been studied in hematologic malignancies such as cutaneous T-cell lymphoma, pDC-AML and blastic plasmacytoid dendritic cells neoplasm -BPDCN, rare and aggressive hematologic malignancy derived from malignant clonal expansion of pDCs.

[0005] Blastic plasmacytoid dendritic cell neoplasm (BPDCN) remains an aggressive, rare, and difificult-to-manage hematologic malignancy with heterogenous and unique manifestations, including involvement of skin, liver, spleen, bone marrow, blood, lymph nodes and central nervous system, with the bone marrow and peripheral blood involvement in 45% of patients. Central nervous system infiltration occurs in about one-third of patients, necessitating routinePATENT DOCKET NO. MDA1380-1WOcerebrospinal fluid screening by flow cytometry. Historically, BPDCN treatments result in poor outcomes, and there is no worldwide consensus on treatment approach. As BPDCN generally affects older adults, many patients are unfit to receive intensive chemotherapy, and although hematopoietic stem cell transplant is preferred for younger, fit individuals, not all are eligible. Given its rarity and aggressiveness, no standard of care treatment exists for BPDCN, and its prognosis is particularly dismal. Currently, treatment is mainly based on high-dose chemotherapy using ALL- or AML-type induction regimens. Notably, novel therapies, such as targeting CD 123, a marker differentially expressed on the surface of BPDCN cells, are in development and tagraxofusp, a fusion protein consisting of interleukin 3 fused to diphtheria toxin, is the first FDA approved agent for this indication. Despite favorable response rates in the frontline setting, many patients experience relapse in the setting of monotherapy, and outcomes in patients with relapsed / refractory BPDCN remain dismal.

[0006] Adoptive T-cell therapy using a chimeric antigen receptor (CAR) represents a promising new avenue in immunotherapy, showing durable remissions in patients with relapsed / refractory hematologic malignancies. BPDCN cells characteristically express CD123 and CD303 (also named BDCA2 / blood dendritic cell antigen 2). To direct effector immune cells to these tumors, efficacy of allogenic CD 123 -targeting chimeric antigen receptor (CAR) T cells has been reported on, which have shown potent anti-tumor activity against an established BPDCN cell line (CAL-1) and CD123+ / BPDCN patient-derived xenograft models. However, the CD123-CAR-T cells may cause on-target, off-tumor toxicity due to the expression of CD 123 on normal CD34+ progenitor cells, monocytes and endothelial cells, and the clinical trial in BPDCN remains on hold due to toxicity seen. Thus, there is a need for novel tumor targets for CAR-T development for BPDCN therapy.SUMMARY OF THE INVENTION

[0007] The present invention is based on the seminal discovery of CD303 as a pDC-specific target for BPDCN immunotherapy, selective antibodies that bind to CD303 and the production of first-in-class CAR-Ts targeting CD303.

[0008] In one embodiment, the present disclosure provides a monoclonal antibody or a fragment thereof that specifically binds to CD303 (BDCA2), including: a heavy chain variable region including a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG) ; and a light chain variable region including a CDRL1 includingPATENT DOCKET NO. MDA1380-1WOa sequence QSVSTSSYGY (SEQ ID NO: 4); a CDRL2 including a sequence YAS (SEQ ID NO: 5); and a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6).

[0009] In some aspects, the monoclonal antibody of the present disclosure includes the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7); and the light chain variable region sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8).

[0010] In one embodiment, the present disclosure provides a monoclonal antibody or a fragment thereof that specifically binds to CD303 (BDCA2), including: the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7); and the light chain variable region sequence having 98% or greater identity to DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8).

[0011] In some aspects, the monoclonal antibody of the present disclosure includes an IgGl heavy chain and a IgK light chain.

[0012] In one embodiment, the present disclosure provides a chimeric antigen receptor (CAR) including an extracellular domain, wherein the extracellular domain includes a heavy chain variable region including a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG) ; and a light chain variable region including a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); a CDRL2 including a sequence YAS (SEQ ID NO: 5); and a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6), wherein the extracellular domain targets CD303.

[0013] In some aspects, the CAR of the present disclosure further includes a transmembrane domain, a linker and an intracellular domain, wherein the transmembrane domain includes a CD 8 hinge and a CD8 transmembrane domain; wherein the intracellular domain includes one or morePATENT DOCKET NO. MDA1380-1WOof an 0X40 costimulatory domain, a CD3z domain, a 4- IBB domain, and a CD28 domain; and wherein the linker includes GGGGSGGGGSGGGGS(SEQ ID NO: 25).

[0014] In some aspects, the extracellular domain includes the heavy chain variable region sequence including the sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7), and the light chain variable region sequence including the sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8).

[0015] In some aspects, the linker is located between the heavy chain variable domain and the light chain variable domain.

[0016] In one embodiment, the present disclosure provides a chimeric antigen receptor (CAR) including an extracellular domain, wherein the extracellular domain includes a heavy chain variable region including the sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7); and a light chain variable region sequence having 98% or greater identity to the sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8), wherein the extracellular domain targets CD303 (BDCA2).

[0017] In some aspects, the extracellular domain includes the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7), and the light chain variable region sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8).

[0018] In some aspects, the CAR of the present disclosure further includes a transmembrane domain, a linker and an intracellular domain, wherein the transmembrane domain includes a CD 8 hinge and a CD8 transmembrane domain; wherein the intracellular domain includes one or morePATENT DOCKET NO. MDA1380-1WOof an 0X40 costimulatory domain, a CD3z domain, a 4- IBB domain, and a CD28 domain; and wherein the linker includes GGGGSGGGGSGGGGS linker (SEQ ID NO: 25).

[0019] In one embodiment, the present disclosure provides a chimeric antigen receptor (CAR) including an extracellular domain, wherein the extracellular domain includes a heavy chain variable region including a CDRH1 including a sequence GFTFST (SEQ ID NO: 9); a CDRH2 including a sequence ISSGGST (SEQ ID NO: 10); a CDRH3 including a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11) ; and a light chain variable region including a CDRL1 including a sequence SQSVDYDGDGF (SEQ ID NO: 12); a CDRL2 including a sequence TAS (SEQ ID NO: 13); and a CDRL3 including a sequence QQSNEDPWT (SEQ ID NO: 14), wherein the extracellular domain targets CD303.

[0020] In some aspects, the CAR of the present disclosure further includes a transmembrane domain, a linker and an intracellular domain, wherein the transmembrane domain includes a CD 8 hinge and a CD8 transmembrane domain; wherein the intracellular domain includes one or more of an 0X40 costimulatory domain, a CD3z domain, a 4- IBB domain, and a CD28 domain; and wherein the linker includes GGGGSGGGGSGGGGSlinker (SEQ ID NO: 25).

[0021] In some aspects, the extracellular domain includes the heavy chain variable region having the sequence of EVKLVESGGGLVKPGGSLKLSCAASGFTFSTMSWVRQTPEKRLEWVASISSGGSTYYPD SVKGRFTISRDNARNILYLQMSSLRSEDTAMYYCARPSYDGYSSWFAYWGQGTLVTVSA(SEQ ID NO: 15), a light chain variable region sequence of DIVLTQSPASLAVSLGQRATISCKASQSVDYDGDGFMNWYQQKPGQPPKLLIYTASNLES GIPARFSGSGSGTDFTLNIHPVEEEDAATYYCQQSNEDPWTFGGGTKLEIK (SEQ ID NO: 16).

[0022] In one embodiment, the present disclosure provides a dual chimeric antigen receptor (CAR) including a first CAR and a second CAR, wherein the first CAR the second CAR include an extracellular domain which is independently selected from a) an extracellular domain including a heavy chain variable region including (i) a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); (ii) a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); (iii) a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG); and a light chain variable region including (i) a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) a CDRL2 including a sequence YAS (SEQ ID NO: 5); and (iii) a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6); b) an extracellular domain including a heavy chain variable region including (i) a CDRH1 including a sequence GFTFST (SEQ ID NO: 9); (ii) a CDRH2 including a sequence ISSGGSTPATENT DOCKET NO. MDA1380-1WO(SEQ ID NO: 10); (iii) a CDRH3 including a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11) ; and a light chain variable region including (i) a CDRL1 including a sequence SQSVDYDGDGF (SEQ ID NO: 12); (ii) a CDRL2 including a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 including a sequence QQSNEDPWT (SEQ ID NO: 14); or c) an extracellular domain including a heavy chain variable region including (i) a CDRH1 including a sequence GFTFSSYT (SEQ ID NO: 17); (ii) a CDRH2 including a sequence SSGGSYT (SEQ ID NO: 18); (iii) a CDRH3 including a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19) ; and a light chain variable region including (i) a CDRL1 including a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 including a sequence LAS (SEQ ID NO: 21); and (ii) a CDRL3 including a sequence QQNNEDPRT (SEQ ID NO: 22) wherein the extracellular domain of the first CAR and / or the second CAR targets CD303.

[0023] In one embodiment, the present disclosure provides a dual chimeric antigen receptor (CAR) including a first CAR and a second CAR, wherein the extracellular domain of the first CAR and / or the second CAR is independently selected from a) an extracellular domain including the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7); and the light chain variable region sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8); b) an extracellular domain including a heavy chain variable region sequence of EVKLVESGGGLVKPGGSLKLSCAASGFTFSTMSWVRQTPEKRLEWVASISSGGSTYYPD SVKGRFTISRDNARNILYLQMSSLRSEDTAMYYCARPSYDGYSSWFAYWGQGTLVTVSA(SEQ ID NO: 15), and a light chain variable region sequence of DIVLTQSPASLAVSLGQRATISCKASQSVDYDGDGFMNWYQQKPGQPPKLLIYTASNLES GIPARFSGSGSGTDFTLNIHPVEEEDAATYYCQQSNEDPWTFGGGTKLEIK (SEQ ID NO: 16); and c) an extracellular domain including a heavy chain variable region sequence of DVKLVESGGGLVKPGGSLNLSCAASGFTFSSYTMSWVRQNPEKRLEWVATISSGGSYTY YPDSVKGRFTISRDNAKNTLYLQMSSLKSEDTAMYYCTRDRGDYDYDEGYYFDYWGQ GTTLTVSS (SEQ ID NO: 23); and a light chain variable region sequence of NIVLTQSPASLAVSLGQRATISCRASASVDSYGNSFMHWYQQKPGQPPKLLIYLASNLES GVPARFSGSGSRTDFTLTIDPVEADDAATYYCQQNNEDPRTFGGGTKLEIK (SEQ ID NO:PATENT DOCKET NO. MDA1380-1WO

[0024] In one embodiment, the present disclosure provides a method of treating a disorder associated with plasmacytoid dendritic cells (pDC) in a subject in need thereof, including delivering to the subject a therapeutically effective amount of the antibody of any one of claims 1-4, the chimeric antigen receptor (CAR) of any one of the embodiments described above, or any one of the dual CAR described above, wherein the antibody, the CAR, or the dual CAR specifically binds to CD303 (BDCA2) and depletes pDC, thereby treating the disorder.

[0025] In one embodiment, the present disclosure provides a method of treating a cancer expressing CD303 (BDCA2) in a subject including delivering to the subject a therapeutically effective amount of the antibody of any one of claims 1-4, the chimeric antigen receptor (CAR) of any one of the embodiments described above, or the dual CAR of any one of claims 14-15, wherein the antibody, the CAR, or the dual CAR specifically binds to CD303 (BDCA2), thereby treating the cancer.

[0026] In some aspects, the method of treatment of the present disclosure further includes pretreatment of the subject with a BCL-2 inhibitor. In some aspects, the BCL-2 inhibitor is Venetoclax.

[0027] In some aspects, the cancer is blastic plasmacytoid dendritic cell neoplasm (BPDCN), acute myelogenous leukemia with clonal expansion of plasmacytoid dendritic cells (pDC-AML), breast cancer, oral squamous cell carcinoma, or non-small cell lung carcinoma.

[0028] In one embodiment, the present disclosure provides a method of diagnosing a tumor with CD303 expression in a subject including detecting CD303 expression in the subject, including contacting the tumor with a monoclonal antibody that specifically binds to CD303, wherein the monoclonal antibody includes a) a heavy chain variable region including (i) a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); (ii) a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); (iii) a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG); and a light chain variable region including (i) a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) a CDRL2 including a sequence YAS (SEQ ID NO: 5); and (iii) a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6); b) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFST (SEQ ID NO: 9); (ii) a CDRH2 including a sequence ISSGGST (SEQ ID NO: 10); (iii) a CDRH3 including a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11) ; and a light chain variable region including (i) a CDRL1 including a sequence SQSVDYDGDGF (SEQ ID NO: 12); (ii) a CDRL2 including a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 including a sequence QQSNEDPWT (SEQ ID NO: 14); or c) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFSSYTPATENT DOCKET NO. MDA1380-1WO(SEQ ID NO: 17); (ii) a CDRH2 including a sequence SSGGSYT (SEQ ID NO: 18); (iii) a CDRH3 including a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19) ; and a light chain variable region including (i) a CDRL1 including a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 including a sequence LAS (SEQ ID NO: 21); and (iii) a CDRL3 including a sequence QQNNEDPRT (SEQ ID NO: 22); thereby diagnosing the tumor with CD303 expression in the subject.

[0029] In one embodiment, the present disclosure provides a method of stratifying a subject with a tumor based on a CD303 expression, the method including contacting the tumor with a monoclonal antibody that specifically binds to CD303, wherein the monoclonal antibody includes: a) a heavy chain variable region including (i) a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); (ii) a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); (iii) a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG); and a light chain variable region including (i) a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) a CDRL2 including a sequence YAS (SEQ ID NO: 5); and (iii) a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6); b) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFST (SEQ ID NO: 9); (ii) a CDRH2 including a sequence ISSGGST (SEQ ID NO: 10); (iii) a CDRH3 including a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11) ; and a light chain variable region including (i) a CDRL1 including a sequence SQSVDYDGDGF (SEQ ID NO: 12); (ii) a CDRL2 including a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 including a sequence QQSNEDPWT (SEQ ID NO: 14); or c) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFSSYT (SEQ ID NO: 17); (ii) a CDRH2 including a sequence SSGGSYT (SEQ ID NO: 18); (iii) a CDRH3 including a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19) ; and a light chain variable region including (i) a CDRL1 including a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 including a sequence LAS (SEQ ID NO: 21); and (iii) a CDRL3 including a sequence QQNNEDPRT (SEQ ID NO: 22).

[0030] In one embodiment, the present disclosure provides an antibody drug conjugate (ADC), including a monoclonal antibody that specifically binds to CD303, wherein the monoclonal antibody includes: a) a heavy chain variable region including (i) a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); (ii) a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); (iii) a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG); and a light chain variable region including (i) a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) a CDRL2 including a sequence YAS (SEQ ID NO: 5); and (iii) a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6); b) a heavy chain variable region including (i) a CDRH1 includingPATENT DOCKET NO. MDA1380-1WOa sequence GFTFST (SEQ ID NO: 9); (ii) a CDRH2 including a sequence ISSGGST (SEQ ID NO: 10); (iii) a CDRH3 including a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11) ; and a light chain variable region including (i) a CDRL1 including a sequence SQSVDYDGDGF (SEQ ID NO: 12); (ii) a CDRL2 including a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 including a sequence QQSNEDPWT (SEQ ID NO: 14); or c) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFSSYT (SEQ ID NO: 17); (ii) a CDRH2 including a sequence SSGGSYT (SEQ ID NO: 18); (iii) a CDRH3 including a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19) ; and a light chain variable region including (i) a CDRL1 including a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 including a sequence LAS (SEQ ID NO: 21); and (iii) a CDRL3 including a sequence QQNNEDPRT (SEQ ID NO: 22).BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a graph that shows expression of BDCA2 in normal tissues and cell lines. Genotype-Tissue Expression database was used to analyze CLEC4C gene expression in various normal tissues.

[0032] FIG. 2 is a graph showing ten anti-BDCA2 antibodies tested in the CT474, and CAL-1 cell lines.

[0033] FIGs. 3A-3C are sequences and schematics that show CAR constructs model. FIG.3A are sequences that show CAR-expression vector pHR-SFFV containing anti-CD303 (scFv, sequences from three different lead anti-CD303 clones) fused downstream of the SFFV lentiviral promotor with classical 2nd generation CAR backbone engineered with CD8 hinge and transmembrane with 0X40 costimulatory domain and CD3z. FIG. 3B is a schematic diagram showing CAR T cell activating immune signaling domains with CD303 CAR construction used in second generation CAR T cells. FIG. 3C is a schematic diagram showing dual CAR construct for an alternate potential strategy. Anti-CD303 and anti-CD304 dual CAR construct containing EGFR safety switch region (for use, if required upon CD303 loss from CD303 CAR-T treatments in vivo).

[0034] FIG. 4 is a graph showing CD303 CAR surface expression. CD303 specific scFvs CARs into Jurkat-NFAT-Luc reporter cells were stained with recombinant HisCD303 protein conjugated with AF647 analyzed using flow cytometry.

[0035] FIG. 5 are graphs showing CD303 CAR expression on cell surface. CAR transduced stable Jurkat-Lucia-NFAT report cells lines. Representatives untransduced and CAR expressionPATENT DOCKET NO. MDA1380-1WOof CAR transduced stable Jurkat-Lucia-NFAT report cells lines. CD303 CAR expression was confirmed with recombinant his-CD303-AF637 using flow cytometry.

[0036] FIGs. 6A-6B are graphs that show luciferase intensity from CD303 -CAR- Jurkat-Lucia-NFAT upon co-culture with BPDCN+ or -ve cells (CAL-1 and OCI-AML3 respectively). Coculture CAR transduced stable Jurkat-Lucia-NFAT report cells lines with target CD303+ve and -ve cell lines. E:T=1:1 After 24 hours incubation, Luciferase were detected. FIG. 6A is a graph showing luciferase intensity from CD303 -CAR- Jurkat-Lucia-NFAT upon co-culture with BPDCN+ cells (CAL-1). FIG. 6B is a graph showing luciferase intensity from CD303-CAR-Jurkat-Lucia-NFAT upon co-culture with BPDCN -ve cells (OCI-AML3 respectively).

[0037] FIG. 7 is a graph that shows antitumor effects of CD303 CAR T cells. Cytotoxicity activity of anti-CD303 (clones 145-99, -125, and 201A) CAR T cells was determined by flow cytometry and percentage of total cell death was analyzed. Primary BPDCN samples were incubated with CD303 CAR T cells. Results were obtained from E:T = 5:1 and 1 : 1 ratios and from day 4.DETAILED DESCRIPTION OF THE INVENTION

[0038] The present invention is based on the seminal discovery of CD303 as a pDC-specific target for BPDCN immunotherapy, selective antibodies that bind CD303 and the production of first-in-class CAR-Ts targeting CD303. CD303 (expressed in cytoplasmic membrane) is selectively expressed in healthyand neoplastic plasmacytoid dendritic cells and is low in healthy tissues, representing an excellent CAR-T target.

[0039] Before the present compositions and methods are described, it is to be understood that this invention is not limited to particular compositions, methods, and experimental conditions described, as such compositions, methods, and conditions may vary. It is also to be understood that the terminology used herein is for purposes of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only in the appended claims.

[0040] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, references to “the method” includes one or more methods, and / or steps of the type described herein which will become apparent to those persons skilled in the art upon reading this disclosure and so forth.PATENT DOCKET NO. MDA1380-1WO

[0041] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0042] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

[0043] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, it will be understood that modifications and variations are encompassed within the spirit and scope of the instant disclosure. The preferred methods and materials are now described.

[0044] In one embodiment, the present disclosure provides a monoclonal antibody or a fragment thereof that specifically binds to CD303 (BDCA2), wherein the antiboding includes a heavy chain variable region including a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG) ; and a light chain variable region including a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); a CDRL2 including a sequence YAS (SEQ ID NO: 5); and a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6).

[0045] As used herein, the term “antibody” refers to an immunoglobulin molecule that has the ability to specifically bind to an antigen. The term “antibody” includes, but is not limited to, monoclonal antibodies, polyclonal antibodies, human antibodies, humanized antibodies, chimeric antibodies, bispecific antibodies, and anti-idiotypic antibodies, unless context clearly indicates otherwise. In one aspect, antibodies provided herein include monoclonal antibodies. Antibodies provided herein include any isotype and class (e.g., IgG, IgE, IgM, IgD, IgA and IgY), or subclass (e.g., IgGl, IgG2, IgG3, IgG4, IgAl and IgA2). As used herein, “antigen binding fragment” means a fragment or portion of an immunoglobulin molecule or antibody that has the ability to specifically bind to the same antigen as the immunoglobulin molecule or antibody. Exemplary antigen binding fragments include but are not limited to scFv, Fab, or F(ab)2 fragments. As used herein “antigen binding region” means the part of an antibody or immunoglobulin molecule that binds to antigens or proteins by contacting the antigen or protein, for example. An antigen binding region generally includes heavy chain variable (VH) regions and light chain variable (VL) regions. An antigen binding region generally includes one or more antigen binding sites or paratopes.PATENT DOCKET NO. MDA1380-1WO

[0046] The antigen binding region of an antibody or antigen binding fragment thereof generally includes complementarity determining regions (CDRs). “Complementarity determining region (CDR)” refers to hypervariable regions of VH and VL. CDRS include the target protein or antigen binding site of an antibody that confers specificity for protein or antigen binding. VH and VL generally include three sequentially numbered CDRs. As used herein, CDR-H1, CDR-H2, and CDR-H3 refer to three consecutively arranged CDRs of the heavy chain variable region (VH), as numbered from the N-terminus of the heavy chain polypeptide. As used herein, CDR-L1, CDR-L2, and CDR-L3 refer to three consecutively arranged CDRs of the light chain variable region (VL), as numbered from the N-terminus of the light chain polypeptide.

[0047] Antibodies provided herein have a VH region including an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to a sequence of SEQ ID NO: 7; SEQ ID NO: 15; or SEQ ID NO: 23. Antibodies provided herein also include an VL region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to a sequence of SEQ ID NO:8; SEQ ID NO: 16; or SEQ ID NO: 24.

[0048] In one aspect, the antigen binding region of the antibody or antigen binding fragment thereof having a VH region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO: 7 and a VL region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO:8 has a CDR-H1 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: la CDR-H2 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, atPATENT DOCKET NO. MDA1380-1WOleast about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 2, and a CDR-H3 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 3. In another aspect, the antigen binding region of the antibody or antigen binding fragment thereof having a VH region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO: 7 and a VL region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO: 8 has a CDR-L1 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 4 a CDR-L2 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 5, and a CDR-L3 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 6.

[0049] In some aspects, the monoclonal antibody of the present disclosure includes the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7); and the light chain variable region sequence ofPATENT DOCKET NO. MDA1380-1WODIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8).

[0050] In one aspect, the antibody or antigen binding fragment thereof has a VH region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 7 and a VL region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO:8. SEQ ID NO: 7 provides an amino acid sequence that includes the variable region of anti-CD303 (BDCA2) antibody clone 145-99-1 heavy chain. SEQ ID NO: 8 provides an amino acid sequence that includes the variable region of anti-CD303 (BDCA2) clone 145-99-1 light chain.

[0051] In one embodiment, the present disclosure provides a monoclonal antibody or a fragment thereof that specifically binds to CD303 (BDCA2), including: the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7); and the light chain variable region sequence having 98% or greater identity to DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8).

[0052] In some aspects, the monoclonal antibody of the present disclosure includes the heavy chain variable region sequence of EVKLVESGGGLVKPGGSLKLSCAASGFTFSTMSWVRQTPEKRLEWVASISSGGSTYYPD SVKGRFTISRDNARNILYLQMSSLRSEDTAMYYCARPSYDGYSSWFAYWGQGTLVTVSA(SEQ ID NO: 15); and the light chain variable region sequence of DIVLTQSPASLAVSLGQRATISCKASQSVDYDGDGFMNWYQQKPGQPPKLLIYTASNLESPATENT DOCKET NO. MDA1380-1WOGIPARFSGSGSGTDFTLNIHPVEEEDAATYYCQQSNEDPWTFGGGTKLEIK (SEQ ID NO: 16).

[0053] In one aspect, the antibody or antigen binding fragment thereof has a VH region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 15 and a VL region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 16. SEQ ID NO: 15 provides an amino acid sequence that includes the variable region of anti-CD303 (BDCA2) antibody clone 145-125-B heavy chain. SEQ ID NO: 16 provides an amino acid sequence that includes the variable region of anti-CD303 (BDCA2) clone 145-125-B light chain.

[0054] In some aspects, the monoclonal antibody of the present disclosure includes the heavy chain variable region sequence of DVKLVESGGGLVKPGGSLNLSCAASGFTFSSYTMSWVRQNPEKRLEWVATISSGGSYTY YPDSVKGRFTISRDNAKNTLYLQMSSLKSEDTAMYYCTRDRGDYDYDEGYYFDYWGQ GTTLTVSS (SEQ ID NO: 23); and the light chain variable region sequence of NIVLTQSPASLAVSLGQRATISCRASASVDSYGNSFMHWYQQKPGQPPKLLIYLASNLES GVPARFSGSGSRTDFTLTIDPVEADDAATYYCQQNNEDPRTFGGGTKLEIK (SEQ ID NO: 24).

[0055] In one aspect, the antibody or antigen binding fragment thereof has a VH region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 23 and a VL region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least aboutPATENT DOCKET NO. MDA1380-1WO92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 24. SEQ ID NO: 23 provides an amino acid sequence that includes the variable region of anti-CD303 (BDCA2) antibody clone 145-201 A heavy chain. SEQ ID NO: 24 provides an amino acid sequence that includes the variable region of anti-CD303 (BDCA2) clone 145 -201 A light chain.

[0056] In some aspects, the monoclonal antibody of the present disclosure includes an IgGl heavy chain and a IgK light chain.

[0057] In one embodiment, the present disclosure provides a chimeric antigen receptor (CAR) including an extracellular domain, wherein the extracellular domain includes a heavy chain variable region including a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG) ; and a light chain variable region including a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); a CDRL2 including a sequence YAS (SEQ ID NO: 5); and a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6), wherein the extracellular domain targets CD303.

[0058] As used herein the term “chimeric antigen receptor” or “CAR” refers to a synthetic engineered receptors that graft a defined specificity and function onto an immune effector cell, typically a T cell, and augment T-cell function to recognize tumor-associated antigens. The CAR protein binds to a specific antigen on the surface of cancer cells. This binding triggers the T cells to activate and kill the cancer cells. In a classical CAR, the specificity of a monoclonal antibody is grafted on to a T cell. CAR is an artificial transmembrane receptor that connects the extracellular antigen recognition domain (ARD), hinge domain (HD), transmembrane domain (TMD), and intracellular signal transduction domain (STD) in tandem. The transmembrane domain spans the cell membrane and is crucial for anchoring the CAR protein and ensuring its stability. The transmembrane domain links the extracellular and intracellular domains and determines the conformation and flexibility of the CAR, allowing efficient binding to the targeted antigen / epitope. In some aspects, the CARs include one or more costimulatory domain. Costimulatory domains are essential components of Chimeric Antigen Receptors (CARs) that enhance T cell activation, proliferation, and survival. The choice of costimulatory domain can be determined by one of ordinary skill in the art to optimize therapeutic outcomes for specific targets and clinical applications. Examples of costimulatory domains include but are not limited to CD28PATENT DOCKET NO. MDA1380-1WOcostimulatory domain, 4-1BB (CD137) costimulatory domain, 0X40 (CD134) costimulatory domain, ICOS costimulatory domain, and CD27 costimulatory domain.

[0059] The hinge domain in CARs is a flexible region that connects the antigen-recognizing domain to the transmembrane domain. It plays a crucial role in providing the necessary flexibility and spatial orientation for the CAR to effectively bind to its target antigen. Examples of hinge domains used in CAR designs include but are not limited to CD8a hinge domain, CD8 hinge domain, and IgG hinge domain.

[0060] In CARs the transmembrane domain (TMD) is a crucial component that anchors the CAR to the T cell membrane and connects the extracellular antigen recognition domain to the intracellular signaling domains. Examples of CAR transmembrane domains include but are not limited to CD3z transmembrane domain, CD4 transmembrane domain, CD8a transmembrane domain, and CD8 transmembrane domain.

[0061] As used herein the term “CD28” refers to a costimulatory molecule that plays a crucial role in the function of CAR, included to improve the efficacy of CAR T cells. When a CAR-T cell binds to its target antigen, the CD28 domain helps to amplify the activation signal. This leads to a stronger and more sustained T cell response, which is essential for effective tumor cell killing.

[0062] The intracellular domain of CARs is crucial for transmitting activation signals into the T cell upon antigen binding. Examples of intracellular domains of CAR include but are not limited to CD3z, CD28, 4-1BB intracellular domain, 0X40 (CD134) intracellular domain, and ICOS intracellular domain.

[0063] The target-antigen binding domain of a CAR is commonly fused via a spacer and transmembrane domain to a signaling endodomain. When the CAR binds the target-antigen, this results in the transmission of an activating signal to the T-cell it is expressed on. The CAR of the present invention includes a CD303 binding domain.

[0064] In some aspects, the CAR of the present disclosure further includes a transmembrane domain, a linker and an intracellular domain, wherein the transmembrane domain includes a CD 8 hinge and a CD8 transmembrane domain; wherein the intracellular domain includes one or more of an 0X40 costimulatory domain a CD3z domain, a 4- IBB domain, and a CD28 domain; and wherein the linker includes GGGGSGGGGSGGGGS (SEQ ID NO: 25).

[0065] In one aspect, the extracellular domain of the CAR having a VH region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO: 7 and a VL region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO:8 has a CDR-H1 that includes an amino acid sequence having at least about 80% identity, at least about 85%PATENT DOCKET NO. MDA1380-1WOidentity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO:1, a CDR-H2 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 2, and a CDR-H3 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 3. In another aspect, the antigen binding region of the antibody or antigen binding fragment thereof having a VH region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO: 7 and a VL region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO: 8 has a CDR-L1 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 4, a CDR-L2 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 5, and a CDR-L3 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least aboutPATENT DOCKET NO. MDA1380-1WO99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 6.

[0066] In some aspects, the extracellular domain includes the heavy chain variable region sequence including the sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7), and the light chain variable region sequence including the sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8).

[0067] In one aspect, the extracellular domain of the CAR has a VH region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 7 and a VL region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO:8. SEQ ID NO: 7 provides an amino acid sequence that includes the variable region of anti-CD303 (BDCA2) antibody clone 145-99-1 heavy chain. SEQ ID NO: 8 provides an amino acid sequence that includes the variable region of anti-CD303 (BDCA2) clone 145-99-1 light chain.

[0068] In some aspects, the linker is located between the heavy chain variable domain and the light chain variable domain.

[0069] In some aspects, the CAR is engineered using a CAR-expression vector. In some aspect the CAR-expression vector is a viral vector. In some aspects the viral vector is a lentiviral vector. In some aspects the lentiviral vector is driven by a (SFFV) promotor, a EFla-1 promotor, or MSCV promotor. In some aspects, the SFFV promotor, the EFla-1 promotor, or MSCV promotor are with a preceding ubiquitous chromatin opening elements (UCOE). In some aspects, the SFFV promotor, the EFla-1 promotor, or MSCV promotor are without a preceding ubiquitous chromatinPATENT DOCKET NO. MDA1380-1WOopening elements (UCOE). In some aspects the lentiviral vector is a pHR-SFFV containing anti-CD303 fused downstream of the SFFV lentiviral promotor with classical 2nd generation CAR backbone engineered with CD8 hinge and transmembrane with 0X40 costimulatory domain and CD3.

[0070] In one embodiment, the present disclosure provides a chimeric antigen receptor (CAR) including an extracellular domain, wherein the extracellular domain includes a heavy chain variable region including the sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7); and a light chain variable region sequence having 98% or greater identity to the sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8), wherein the extracellular domain targets CD303 (BDCA2).

[0071] In some aspects, the extracellular domain includes the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEP TYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7), and the light chain variable region sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8).

[0072] In some aspects, the CAR of the present disclosure further includes a transmembrane domain, a linker and an intracellular domain, wherein the transmembrane domain includes a CD 8 hinge and a CD8 transmembrane domain; wherein the intracellular domain includes one or more of an 0X40 costimulatory domain, a CD3z domain, a 4- IBB domain, and a CD28 domain; and wherein the linker includes GGGGSGGGGSGGGGSlinker (SEQ ID NO: 25).

[0073] In some aspects, the linker is located between the heavy chain variable domain and the light chain variable domain.

[0074] In one embodiment, the present disclosure provides a chimeric antigen receptor (CAR) including an extracellular domain, wherein the extracellular domain includes a heavy chain variable region including a CDRH1 including a sequence GFTFST (SEQ ID NO: 9); a CDRH2 including a sequence ISSGGST (SEQ ID NO: 10); a CDRH3 including a sequencePATENT DOCKET NO. MDA1380-1WOARPSYDGYSSWFAY (SEQ ID NO: 11) ; and a light chain variable region including a CDRL1 including a sequence SQSVDYDGDGF (SEQ ID NO: 12); a CDRL2 including a sequence TAS (SEQ ID NO: 13); and a CDRL3 including a sequence QQSNEDPWT (SEQ ID NO: 14), wherein the extracellular domain targets CD303.

[0075] In one aspect, the extracellular domain of the CAR having a VH region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO: 15 and a VL region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO: 16 has a CDR-H1 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO:9, a CDR-H2 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 10, and a CDR-H3 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 11. In another aspect, the antigen binding region of the antibody or antigen binding fragment thereof having a VH region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO: 15 and a VL region that includes an amino acid sequence having at least about 80% identity to SEQ ID NO: 16 has a CDR-L1 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 12, a CDR-L2 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at leastPATENT DOCKET NO. MDA1380-1WOabout 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 13, and a CDR-L3 that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 14.

[0076] In some aspects, the CAR of the present disclosure further includes a transmembrane domain, a linker and an intracellular domain, wherein the transmembrane domain includes a CD 8 hinge and a CD8 transmembrane domain; wherein the intracellular domain includes one or more of an 0X40 costimulatory domain, a CD3z domain, a 4- IBB domain, and a CD28 domain; and wherein the linker includes GGGGSGGGGSGGGGS linker (SEQ ID NO: 25).

[0077] In some aspects, the extracellular domain includes the heavy chain variable region having the sequence of EVKLVESGGGLVKPGGSLKLSCAASGFTFSTMSWVRQTPEKRLEWVASISSGGSTYYPD SVKGRFTISRDNARNILYLQMSSLRSEDTAMYYCARPSYDGYSSWFAYWGQGTLVTVSA(SEQ ID NO: 15), a light chain variable region sequence of DIVLTQSPASLAVSLGQRATISCKASQSVDYDGDGFMNWYQQKPGQPPKLLIYTASNLES GIPARFSGSGSGTDFTLNIHPVEEEDAATYYCQQSNEDPWTFGGGTKLEIK (SEQ ID NO: 16).

[0078] In one aspect, the extracellular domain of the CAR has a VH region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 15 and a VL region that includes an amino acid sequence having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity,PATENT DOCKET NO. MDA1380-1WOat least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 16. SEQ ID NO: 15 provides an amino acid sequence that includes the variable region of anti-CD303 (BDCA2) antibody clone 145-125-B heavy chain. SEQ ID NO: 16 provides an amino acid sequence that includes the variable region of anti-CD303 (BDCA2) clone 145-125-B light chain.

[0079] In some aspects, the linker is located between the heavy chain variable domain and the light chain variable domain.

[0080] In one embodiment, the present disclosure provides a dual chimeric antigen receptor (CAR) including a first CAR and a second CAR, wherein the first CAR the second CAR include an extracellular domain which is independently selected from a) an extracellular domain including a heavy chain variable region including (i) a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); (ii) a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); (iii) a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG); and a light chain variable region including (i) a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) a CDRL2 including a sequence YAS (SEQ ID NO: 5); and (iii) a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6); b) an extracellular domain including a heavy chain variable region including (i) a CDRH1 including a sequence GFTFST (SEQ ID NO: 9); (ii) a CDRH2 including a sequence ISSGGST (SEQ ID NO: 10); (iii) a CDRH3 including a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11); and a light chain variable region including (i) a CDRL1 including a sequence SQSVDYDGDGF (SEQ ID NO: 12); (ii) a CDRL2 including a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 including a sequence QQSNEDPWT (SEQ ID NO: 14); or c) an extracellular domain including a heavy chain variable region including (i) a CDRH1 including a sequence GFTFSSYT (SEQ ID NO: 17); (ii) a CDRH2 including a sequence SSGGSYT (SEQ ID NO: 18); (iii) a CDRH3 including a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19) ; and a light chain variable region including (i) a CDRL1 including a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 including a sequence LAS (SEQ ID NO: 21); and (ii) a CDRL3 including a sequence QQNNEDPRT (SEQ ID NO: 22) wherein the extracellular domain of the first CAR and / or the second CAR targets CD303.

[0081] In one aspect, the extracellular domain of the CAR has a) an extracellular domain including a heavy chain variable region including (i) a CDRH1 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least aboutPATENT DOCKET NO. MDA1380-1WO99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 1; (ii) a CDRH2 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 2; (iii) a CDRH3 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 3; and a light chain variable region including (i) a CDRL1 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 4; (ii) a CDRL2 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 5; and (iii) a CDRL3 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 6; b) an extracellular domain including a heavy chain variable region including (i) a CDRH1 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 9; (ii) a CDRH2 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least aboutPATENT DOCKET NO. MDA1380-1WO91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 10; (iii) a CDRH3 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 11 ; and a light chain variable region including (i) a CDRL1 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 12; (ii) a CDRL2 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 12; and (iii) a CDRL3 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 13; and (iii) a CDRL3 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 14; or c) an extracellular domain including a heavy chain variable region including (i) a CDRH1 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least aboutPATENT DOCKET NO. MDA1380-1WO99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 17; (ii) a CDRH2 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 18; (iii) a CDRH3 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 19; and a light chain variable region including (i) a CDRL1 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 20; (ii) a CDRL2 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 21; and (ii) a CDRL3 having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 22 wherein the extracellular domain of the first CAR and / or the second CAR targets CD303.

[0082] In one embodiment, the present disclosure provides a dual chimeric antigen receptor (CAR) including a first CAR and a second CAR, wherein the extracellular domain of the first CAR and / or the second CAR is independently selected from a) an extracellular domain including the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWMGWINTETGEPPATENT DOCKET NO. MDA1380-1WOTYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGKDDYDRVAYWGQGTLVTVSA(SEQ ID NO: 7); and the light chain variable region sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLIKYASNLES GVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGGTKLEIK (SEQ ID NO: 8); b) an extracellular domain including a heavy chain variable region sequence of EVKLVESGGGLVKPGGSLKLSCAASGFTFSTMSWVRQTPEKRLEWVASISSGGSTYYPD SVKGRFTISRDNARNILYLQMSSLRSEDTAMYYCARPSYDGYSSWFAYWGQGTLVTVSA(SEQ ID NO: 15), and a light chain variable region sequence of DIVLTQSPASLAVSLGQRATISCKASQSVDYDGDGFMNWYQQKPGQPPKLLIYTASNLES GIPARFSGSGSGTDFTLNIHPVEEEDAATYYCQQSNEDPWTFGGGTKLEIK (SEQ ID NO: 16); and c) an extracellular domain including a heavy chain variable region sequence of DVKLVESGGGLVKPGGSLNLSCAASGFTFSSYTMSWVRQNPEKRLEWVATISSGGSYTY YPDSVKGRFTISRDNAKNTLYLQMSSLKSEDTAMYYCTRDRGDYDYDEGYYFDYWGQ GTTLTVSS (SEQ ID NO: 23); and a light chain variable region sequence of NIVLTQSPASLAVSLGQRATISCRASASVDSYGNSFMHWYQQKPGQPPKLLIYLASNLES GVPARFSGSGSRTDFTLTIDPVEADDAATYYCQQNNEDPRTFGGGTKLEIK (SEQ ID NO: 24).

[0083] In one aspect, the extracellular domain of the CAR has a) an extracellular domain including the heavy chain variable region having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 7, and the light chain variable region having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 8; b) an extracellular domain including a heavy chain variable region having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least aboutPATENT DOCKET NO. MDA1380-1WO99.9% identity, and any number or range in between, to SEQ ID NO: 15, and a light chain variable region having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 16; and c) an extracellular domain including a heavy chain variable region having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 23; and a light chain variable region having at least about 80% identity, at least about 85% identity, at least about 90% identity, at least about 91% identity, at least about 92% identity, at least about 93% identity, at least about 94% identity, at least about 95% identity, at least about 96% identity, at least about 97% identity, at least about 98% identity, at least about 99% identity, at least about 99.5% identity, at least about 99.9% identity, and any number or range in between, to SEQ ID NO: 24.

[0084] In one embodiment, the present disclosure provides a method of treating a disorder associated with plasmacytoid dendritic cells (pDC) in a subject in need thereof, including delivering to the subject a therapeutically effective amount of any of the antibody described above, the chimeric antigen receptor (CAR) of any one of the embodiments described above, or any one of the dual CAR described above, wherein the antibody, the CAR, or the dual CAR specifically binds to CD303 (BDCA2) and depletes pDC, thereby treating the disorder.

[0085] As used herein the term “plasmacytoid dendritic cells” or “pDCs” refers to a type of immune cell that play a crucial role in the body’s defense against viral infections. pDCs present viral antigens to T cells, which then activate and proliferate to fight the infection. pDCs also play a role in maintaining immune tolerance, preventing the body from attacking its own tissues. pDCs are essential for the body's response to viral infections, such as influenza and HIV. Examples of disorders associated with pDCs include but are not limited autoimmune and inflammatory diseases, lupus, psoriasis, atopic dermatitis, cancers, blastic plasmacytoid dendritic cell neoplasm (BPDCN).

[0086] In one embodiment, the present disclosure provides a method of treating a cancer expressing CD303 (BDCA2) in a subject including delivering to the subject a therapeuticallyPATENT DOCKET NO. MDA1380-1WOeffective amount of any of the antibodies described above, the chimeric antigen receptor (CAR) of any one of the embodiments described above, or the dual CAR of any one of claims 14-15, wherein the antibody, the CAR, or the dual CAR specifically binds to CD303 (BDCA2), thereby treating the cancer.

[0087] The term “cancer” refers to a group of diseases characterized by abnormal and uncontrolled cell proliferation starting at one site (primary site) with the potential to invade and to spread to other sites (secondary sites, metastases) which differentiate cancer (malignant tumor) from benign tumor. Virtually all the organs can be affected, leading to more than 100 types of cancer that can affect humans. Cancers can result from many causes including genetic predisposition, viral infection, exposure to ionizing radiation, exposure environmental pollutant, tobacco and or alcohol use, obesity, poor diet, lack of physical activity or any combination thereof.

[0088] Exemplary cancers include but are not limited to Acute Lymphoblastic Leukemia, Adult; Acute Lymphoblastic Leukemia, Childhood; Acute Myeloid Leukemia, Adult; Adrenocortical Carcinoma; Adrenocortical Carcinoma, Childhood; AIDS-Related Lymphoma; AIDS-Related Malignancies; Blastic plasmacytoid dendritic cell neoplasm (BPDCN); Anal Cancer; Astrocytoma, Childhood Cerebellar; Astrocytoma, Childhood Cerebral; Bile Duct Cancer, Extrahepatic; Bladder Cancer; Bladder Cancer, Childhood; Bone Cancer, Osteosarcoma / Malignant Fibrous Histiocytoma; Brain Stem Glioma, Childhood; Brain Tumor, Adult; Brain Tumor, Brain Stem Glioma, Childhood; Brain Tumor, Cerebellar Astrocytoma, Childhood; Brain Tumor, Cerebral Astrocytoma / Malignant Glioma, Childhood; Brain Tumor, Ependymoma, Childhood; Brain Tumor, Medulloblastoma, Childhood; Brain Tumor, Supratentorial Primitive Neuroectodermal Tumors, Childhood; Brain Tumor, Visual Pathway and Hypothalamic Glioma, Childhood; Brain Tumor, Childhood (Other); Breast Cancer; Breast Cancer and Pregnancy; Breast Cancer, Childhood; Breast Cancer, Male; Bronchial Adenomas / Carcinoids, Childhood: Carcinoid Tumor, Childhood; Carcinoid Tumor, Gastrointestinal; Carcinoma, Adrenocortical; Carcinoma, Islet Cell; Carcinoma of Unknown Primary; Central Nervous System Lymphoma, Primary; Cerebellar Astrocytoma, Childhood; Cerebral Astrocytoma / Malignant Glioma, Childhood; Cervical Cancer; Childhood Cancers; Chronic Lymphocytic Leukemia; Chronic Myelogenous Leukemia; Chronic Myeloproliferative Disorders; Clear Cell Sarcoma of Tendon Sheaths; Colon Cancer; Colorectal Cancer, Childhood; Cutaneous T-Cell Lymphoma; Endometrial Cancer; Ependymoma, Childhood; Epithelial Cancer, Ovarian; Esophageal Cancer; Esophageal Cancer, Childhood; Ewing's Family of Tumors; Extracranial Germ Cell Tumor, Childhood; Extragonadal Germ Cell Tumor; Extrahepatic BilePATENT DOCKET NO. MDA1380-1WODuct Cancer; Eye Cancer, Intraocular Melanoma; Eye Cancer, Retinoblastoma; Gallbladder Cancer; Gastric (Stomach) Cancer; Gastric (Stomach) Cancer, Childhood; Gastrointestinal Carcinoid Tumor; Germ Cell Tumor, Extracranial, Childhood; Germ Cell Tumor, Extragonadal; Germ Cell Tumor, Ovarian; Gestational Trophoblastic Tumor; Glioma. Childhood Brain Stem; Glioma. Childhood Visual Pathway and Hypothalamic; Hairy Cell Leukemia; Head and Neck Cancer; Hepatocellular (Liver) Cancer, Adult (Primary); Hepatocellular (Liver) Cancer, Childhood (Primary); Hodgkin's Lymphoma, Adult; Hodgkin's Lymphoma, Childhood; Hodgkin's Lymphoma During Pregnancy; Hypopharyngeal Cancer; Hypothalamic and Visual Pathway Glioma, Childhood; Intraocular Melanoma; Islet Cell Carcinoma (Endocrine Pancreas); Kaposi's Sarcoma; Kidney Cancer; Laryngeal Cancer; Laryngeal Cancer, Childhood; Leukemia, Acute Lymphoblastic, Adult; Leukemia, Acute Lymphoblastic, Childhood; Leukemia, Acute Myeloid, Adult; Leukemia, Acute Myeloid, Childhood; Leukemia, Chronic Lymphocytic; Leukemia, Chronic Myelogenous; Leukemia, Hairy Cell; Lip and Oral Cavity Cancer; Liver Cancer, Adult (Primary); Liver Cancer, Childhood (Primary); Lung Cancer, Non-Small Cell; Lung Cancer, Small Cell; Lymphoblastic Leukemia, Adult Acute; Lymphoblastic Leukemia, Childhood Acute; Lymphocytic Leukemia, Chronic; Lymphoma, AIDS — Related; Lymphoma, Central Nervous System (Primary); Lymphoma, Cutaneous T-Cell; Lymphoma, Hodgkin's, Adult; Lymphoma, Hodgkin's; Childhood; Lymphoma, Hodgkin's During Pregnancy; Lymphoma, Non-Hodgkin's, Adult; Lymphoma, Non-Hodgkin's, Childhood; Lymphoma, Non-Hodgkin's During Pregnancy; Lymphoma, Primary Central Nervous System; Macroglobulinemia, Waldenstrom's; Male Breast Cancer; Malignant Mesothelioma, Adult; Malignant Mesothelioma, Childhood; Malignant Thymoma; Medulloblastoma, Childhood; Melanoma; Melanoma, Intraocular; Merkel Cell Carcinoma; Mesothelioma, Malignant; Metastatic Squamous Neck Cancer with Occult Primary; Multiple Endocrine Neoplasia Syndrome, Childhood; Multiple Myeloma / Plasma Cell Neoplasm; Mycosis Fungoides; Myelodysplasia Syndromes; Myelogenous Leukemia, Chronic; Myeloid Leukemia, Childhood Acute; Myeloma, Multiple; Myeloproliferative Disorders, Chronic; Nasal Cavity and Paranasal Sinus Cancer; Nasopharyngeal Cancer; Nasopharyngeal Cancer, Childhood; Neuroblastoma; Non-Hodgkin's Lymphoma, Adult; Non-Hodgkin's Lymphoma, Childhood; Non-Hodgkin's Lymphoma During Pregnancy; Non-Small Cell Lung Cancer; Oral Cancer, Childhood; Oral Cavity and Lip Cancer; Oropharyngeal Cancer; Osteosarcoma / Malignant Fibrous Histiocytoma of Bone; Ovarian Cancer, Childhood; Ovarian Epithelial Cancer; Ovarian Germ Cell Tumor; Acute Myelogenous Leukemia with Clonal Expansion of Plasmacytoid Dendritic Cells (pDC-AML); Ovarian Low Malignant Potential Tumor; Pancreatic Cancer; PancreaticPATENT DOCKET NO. MDA1380-1WOCancer, Childhood', Pancreatic Cancer, Islet Cell; Paranasal Sinus and Nasal Cavity Cancer; Parathyroid Cancer; Penile Cancer; Pheochromocytoma; Pineal and Supratentorial Primitive Neuroectodermal Tumors, Childhood; Pituitary Tumor; Plasma Cell Neoplasm / Multiple Myeloma; Pleuropulmonary Blastoma; Pregnancy and Breast Cancer; Pregnancy and Hodgkin's Lymphoma; Pregnancy and Non-Hodgkin's Lymphoma; Oral Squamous Cell Carcinoma; Nonsmall Cell Lung Carcinoma; Primary Central Nervous System Lymphoma; Primary Liver Cancer, Adult; Primary Liver Cancer, Childhood; Prostate Cancer; Rectal Cancer; Renal Cell (Kidney) Cancer; Renal Cell Cancer, Childhood; Renal Pelvis and Ureter, Transitional Cell Cancer; Retinoblastoma; Rhabdomyosarcoma, Childhood; Salivary Gland Cancer; Salivary Gland Cancer, Childhood; Sarcoma, Ewing's Family of Tumors; Sarcoma, Kaposi's; Sarcoma (Osteosarcoma Malignant Fibrous Histiocytoma of Bone; Sarcoma, Rhabdomyosarcoma, Childhood; Sarcoma, Soft Tissue, Adult; Sarcoma, Soft Tissue, Childhood; Sezary Syndrome; Skin Cancer; Skin Cancer, Childhood; Skin Cancer (Melanoma); Skin Carcinoma, Merkel Cell; Small Cell Lung Cancer; Small Intestine Cancer; Soft Tissue Sarcoma, Adult; Soft Tissue Sarcoma, Childhood; Squamous Neck Cancer with Occult Primary, Metastatic; Stomach (Gastric) Cancer; Stomach (Gastric) Cancer, Childhood; Supratentorial Primitive Neuroectodermal Tumors, Childhood; T-Cell Lymphoma, Cutaneous; Testicular Cancer; Thymoma, Childhood; Thymoma, Malignant; Thyroid Cancer; Thyroid Cancer, Childhood; Transitional Cell Cancer of the Renal Pelvis and Ureter; Trophoblastic Tumor, Gestational; Unknown Primary Site, Cancer of, Childhood; Unusual Cancers of Childhood; Ureter and Renal Pelvis, Transitional Cell Cancer; Urethral Cancer; Uterine Sarcoma; Vaginal Cancer; Visual Pathway and Hypothalamic Glioma, Childhood; Vulvar Cancer; Waldenstrom's Macro globulinemia; and Wilms' Tumor.

[0089] The term “subject” as used herein refers to any individual or patient to which the subject methods are performed. Generally, the subject is human, although as will be appreciated by those in the art, the subject may be a non-human animal. Thus, other animals, including vertebrate such as rodents (including mice, rats, hamsters, and guinea pigs), cats, dogs, rabbits, farm animals including cows, horses, goats, sheep, pigs, chickens, etc., and primates (including monkeys, chimpanzees, orangutans and gorillas) are included within the definition of subject.

[0090] The term "treatment" is used interchangeably herein with the term "therapeutic method" or “therapy” and refers to 1) therapeutic treatments or measures that cure, slow down, lessen symptoms of, and / or halt progression of a diagnosed pathologic conditions or disorder, and / or 2) prophylactic / preventative measures. Those in need of treatment may include individuals alreadyPATENT DOCKET NO. MDA1380-1WOhaving a particular medical disorder as well as those who may ultimately acquire the disorder (i.e., those needing preventive measures).

[0091] The terms “therapeutically effective amount”, “effective dose,” “therapeutically effective dose”, “effective amount,” or the like refer to that amount of the subject compound that will elicit the biological or medical response of a tissue, system, animal or human that is being sought by the researcher, veterinarian, medical doctor or other clinician. Generally, the response is either amelioration of symptoms in a patient or a desired biological outcome (e.g., inhibit cancer growth). Such amount should be sufficient to treat cancer. The effective amount can be determined as described herein.

[0092] The terms “delivering” or “administration of’ and or “administering” should be understood to mean providing a pharmaceutical composition in a therapeutically effective amount to the subject in need of treatment. Administration routes can be enteral, topical, or parenteral. As such, administration routes include but are not limited to intracutaneous, subcutaneous, intravenous, intraperitoneal, intraarterial, intrathecal, intracapsular, intraorbital, intracardiac, intradermal, transdermal, transtracheal, subcuticular, intraarticulare, subcapsular, subarachnoid, intraspinal and intrastemal, oral, sublingual buccal, rectal, vaginal, nasal ocular administrations, as well infusion, inhalation, and nebulization. The phrases “parenteral administration” and “administered parenterally” as used herein means modes of administration other than enteral and topical administration.

[0093] Examples of delivery or administration include but is not limited to inhalation, otic, buccal, conjunctival, dental, endocervical, endosinusial, endotracheal, enteral, epidural, extra-amniotic, extracorporeal, hemodialysis, infiltration, interstitial, intraabdominal, intraamniotic, intraarterial, intraarticular, intrabiliary, intrabronchial, intrabursal, intracardiac, intracartilaginous, intracaudal, intracavernous, intracavitary, intracerebroventricular, intracisternal, intracorneal, intracoronal, intracoronary, intracorpous cavernaosum, intradermal, intradiscal, intraductal, intraduodenal, intradural, intraepidermal, intraesophageal, intragastric, intragingival, intrahippocampal, intraileal, intralesional, intraluminal, intralymphatic, intramedullary, intrameningeal, intramuscular, intraocular, intraovarian, intrapericardial, intraperitoneal, intrapleural, intraprostatic, intrapulmonary, intrasinal, intraspinal, intrasynovial, intratendinous, intratesticular, intrathoracic, intratubular, intratumor, intratympanic, intrauterine, intravascular, intravenous, intravenous bolus, intravenous drip, intravesical, intravitreal, iontophoresis, irrigation, laryngeal, nasal, nasogastric, ophthalmic, oral, oropharyngeal, parenteral, percutaneous, periarticular, peridural, perineural, periodontal, rectal, retrobulbar, subarachnoid,PATENT DOCKET NO. MDA1380-1WOsubconjunctival, subcutaneous, sublingual, submucosal, topical, transdermal, transmucosal, transplacental, transtracheal, transtympanic, ureteral, urethral, vaginal, infraorbital, intraparenchymal, intrathecal, intraventricular, stereotactic administration, or any combination thereof.

[0094] In some aspects, the method of treatment of the present disclosure further includes pretreatment of the subject with a BCL-2 inhibitor.

[0095] As used herein the term “Bcl-2” or “B-cell lymphoma 2” refers to a protein that controls whether a cell lives or dies by blocking apoptosis, or programmed cell death. Bcl-2 is the first identified apoptosis regulator in any organism. Bcl-2 family proteins are targets for cancer treatment.

[0096] As used herein the term “Bcl-2 inhibitor” refers to a class of drugs that target and inhibit the B-cell lymphoma 2 (Bcl-2) protein. Bcl-2 inhibitors bind to Bcl-2 and disrupt its interaction with other proteins involved in apoptosis. This allows pro-apoptotic proteins, such as Bax and Bid, to activate the apoptotic pathway, leading to cell death. Bcl-2 inhibitors are primarily used to treat certain types of cancers. Examples of Bcl-2 inhibitors include but are not limited to Venetoclax (Venkeyta), Navitoclax (ArQiva), Oblimersen (G3139), ABT-737, Gossypol (AT-101), UMI-77, BDA-366, TW-37, Apogossypol, Maritoclax, Subatoclax, and Obatoclax (GSK’963).

[0097] In some aspects, the BCL-2 inhibitor is Venetoclax.

[0098] In some aspects, the cancer is blastic plasmacytoid dendritic cell neoplasm (BPDCN), acute myelogenous leukemia with clonal expansion of plasmacytoid dendritic cells (pDC-AML), breast cancer, oral squamous cell carcinoma, or non-small cell lung carcinoma.

[0099] As used herein the term “blastic plasmacytoid dendritic cell neoplasm” or “BPDCN” refers to a rare and aggressive type of blood cancer that affects the bone marrow and other organs, such as the skin, lymph nodes, and spleen.

[0100] As used herein the term “acute myelogenous leukemia with clonal expansion of plasmacytoid dendritic cells” or “pDC-AML” refers to a type of leukemia that's characterized by the abnormal proliferation of plasmacytoid dendritic cells (pDCs) in the bone marrow. pDC-AML is a distinct subset of acute myeloid leukemia (AML).

[0101] As used herein the term “oral squamous cell carcinoma” refers to a type of cancer that originates from the squamous cells lining the inside of the mouth, making it the most common form of oral cancer, oral squamous cell carcinoma can develop on the lips, tongue, floor of the mouth, and gums, and is often associated with risk factors such as tobacco use, excessive alcohol consumption, and poor oral hygiene.PATENT DOCKET NO. MDA1380-1WO

[0102] As used herein the term “non-small cell lung carcinoma” refers to a type of lung cancer that is not classified as small cell lung cancer, making it the most common form of lung cancer, usually growing and spreading more slowly than small cell lung cancer. The main types of non-small cell lung carcinoma include but are not limited to adenocarcinoma, squamous cell carcinoma, and large cell carcinoma, and are often associated with smoking as a risk factor.

[0103] In one embodiment, the present disclosure provides a method of diagnosing a tumor with CD303 expression in a subject including detecting CD303 expression in the subject, including contacting the tumor with a monoclonal antibody that specifically binds to CD303, wherein the monoclonal antibody includes a) a heavy chain variable region including (i) a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); (ii) a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); (iii) a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG); and a light chain variable region including (i) a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) a CDRL2 including a sequence YAS (SEQ ID NO: 5); and (iii) a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6); b) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFST (SEQ ID NO: 9); (ii) a CDRH2 including a sequence ISSGGST (SEQ ID NO: 10); (iii) a CDRH3 including a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11) ; and a light chain variable region including (i) a CDRL1 including a sequence SQSVDYDGDGF (SEQ ID NO: 12); (ii) a CDRL2 including a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 including a sequence QQSNEDPWT (SEQ ID NO: 14); or c) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFSSYT (SEQ ID NO: 17); (ii) a CDRH2 including a sequence SSGGSYT (SEQ ID NO: 18); (iii) a CDRH3 including a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19) ; and a light chain variable region including (i) a CDRL1 including a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 including a sequence LAS (SEQ ID NO: 21); and (iii) a CDRL3 including a sequence QQNNEDPRT (SEQ ID NO: 22), thereby diagnosing the tumor with CD303 expression in the subject.

[0104] In one aspect, the subject is administered a therapeutically effective amount of any of the antibodies, the chimeric antigen receptor (CAR), or the dual CAR described above, wherein the antibody, the CAR, or the dual CAR specifically binds to CD303 (BDCA2), if the subject is diagnosed with the tumor with CD303 expression.

[0105] In one embodiment, the present disclosure provides a method of stratifying a subject with a tumor based on a CD303 expression, the method including contacting the tumor with a monoclonal antibody that specifically binds to CD303, wherein the monoclonal antibody includes:PATENT DOCKET NO. MDA1380-1WOa) a heavy chain variable region including (i) a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); (ii) a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); (iii) a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG); and a light chain variable region including (i) a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) a CDRL2 including a sequence YAS (SEQ ID NO: 5); and (iii) a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6); b) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFST (SEQ ID NO: 9); (ii) a CDRH2 including a sequence ISSGGST (SEQ ID NO: 10); (iii) a CDRH3 including a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11) ; and a light chain variable region including (i) a CDRL1 including a sequence SQSVDYDGDGF (SEQ ID NO: 12); (ii) a CDRL2 including a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 including a sequence QQSNEDPWT (SEQ ID NO: 14); or c) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFSSYT (SEQ ID NO: 17); (ii) a CDRH2 including a sequence SSGGSYT (SEQ ID NO: 18); (iii) a CDRH3 including a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19) ; and a light chain variable region including (i) a CDRL1 including a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 including a sequence LAS (SEQ ID NO: 21); and (iii) a CDRL3 including a sequence QQNNEDPRT (SEQ ID NO: 22); thereby stratifying the subject with the tumor based on the CD303 expression.

[0106] As used herein the term “subject stratification” or “stratifying subjects” refers to the process of dividing subjects into groups based on similar characteristics. This can be done to improve care management, treatment, and resource allocation. In some aspects, the subjects are stratified as CD303+ and CD303- tumor. In some embodiments subjects with a tumor are stratified based on an increase in CD303 expression. For example the expression of CD303 may be increased by a 0.25-fold, 0.5-fold, a 0.75-fold, a 1.25-fold, a 1.5-fold, a 2-fold, a 2.5-fold, a 3-fold, a 4-fold, a 5-fold, a 10-fold or more compared to levels of CD303 expression in a healthy subject or the CD303 expression levels in a subject with a CD303- tumor. In some aspect, the subjects stratified in the CD303+ tumor group are treated with the antibodies, the CARs, or the dual CARs described above.

[0107] In one embodiment, the present disclosure provides an antibody drug conjugate (ADC), including a monoclonal antibody that specifically binds to CD303, wherein the monoclonal antibody includes: a) a heavy chain variable region including (i) a CDRH1 including a sequence GYTFTDFS (SEQ ID NO: 1); (ii) a CDRH2 including a sequence INTETGEP (SEQ ID NO: 2); (iii) a CDRH3 including a sequence GKDDYDRVAY (SEQ ID NOG); and a light chain variable region including (i) a CDRL1 including a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) aPATENT DOCKET NO. MDA1380-1WOCDRL2 including a sequence YAS (SEQ ID NO: 5); and (iii) a CDRL3 including a sequence QHSWEIPYT (SEQ ID NO: 6); b) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFST (SEQ ID NO: 9); (ii) a CDRH2 including a sequence ISSGGST (SEQ ID NO: 10); (iii) a CDRH3 including a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11) ; and a light chain variable region including (i) a CDRL1 including a sequence SQSVDYDGDGF (SEQ ID NO: 12); (ii) a CDRL2 including a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 including a sequence QQSNEDPWT (SEQ ID NO: 14); or c) a heavy chain variable region including (i) a CDRH1 including a sequence GFTFSSYT (SEQ ID NO: 17); (ii) a CDRH2 including a sequence SSGGSYT (SEQ ID NO: 18); (iii) a CDRH3 including a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19) ; and a light chain variable region including (i) a CDRL1 including a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 including a sequence LAS (SEQ ID NO: 21); and (iii) a CDRL3 including a sequence QQNNEDPRT (SEQ ID NO: 22).

[0108] As used herein the term “antibody-drug conjugate” or “ADC” refers to a type of cancer treatment that combines a monoclonal antibody, specifically designed to target a particular antigen on cancer cells, with a cytotoxic payload via a linker molecule. ADCs allow the antibody to deliver the potent drug directly to the targeted tumor cells while minimizing damage to healthy tissues. A linker is a chemically engineered molecule that connects the antibody to the cytotoxic payload, designed to be stable in the bloodstream but cleaved upon reaching the target cancer cell, releasing the active drug.

[0109] Presented below are examples discussing anti-CD303 antibody and CAR thereof contemplated for the discussed applications. The following examples are provided to further illustrate the embodiments of the present invention but are not intended to limit the scope of the invention. While they are typical of those that might be used, other procedures, methodologies, or techniques known to those skilled in the art may alternatively be used.EXAMPLES

[0110] Ten lead monoclonal antibodies (MAbs) have been generated and validated using hybridoma technology against human CD303. It was confirmed that these lead MAbs consistently bound to human BPDCN cells (CAL-1 and murine CT474-huCD303 over-expressing cell line), but not to control cells (OCI-AML3, CD303-negative). These MAbs generated in-house will be used to develop a novel CAR-T cell product to target BPDCN. Chimeric receptors have been generated using lentiviral-cloned CD303 / CAR-T cells, and Jurkat-Lucia NFAT cell line wasPATENT DOCKET NO. MDA1380-1WOtransduced with CD303 to serve as an anti-CD303-CAR-T reporter model (CD303-NFAT). Upon coculture with CAL-1 and GEN2.2 BPDCN cells, CD303-NFAT-mediated luciferase was observed, indicating BPDCN-specific activation of T cells. With the goal of selective targeting BPDCN-specific CD303, anti-CD303-CAR-T cells were generated, and positive clones selected based on strong specific binding. In the present disclosure is described that CAR-T cells against CD303 demonstrate high anti-tumor activity in BPDCN pre-clinical models, selectively targeting BPDCN while sparing normal cells.EXAMPLE 1METHODS RNA extraction

[0111] Total RNA was extracted from the hybridoma clone cell pellet using RNA extraction protocol.RT-PCR

[0112] Total RNA was reverse-transcribed into cDNA using isotype-specific anti-sense primers and universal primers following the technical manual of SMARTer RACE 573’ 1st Strand cDNA Synthesis Kit. Antibody fragments of heavy chain and light chain were amplified according to the standard operating procedure (SOP) of rapid amplification of cDNA ends (RACE) of our Core Facility. Amplified antibody fragments were cloned into a standard cloning vector separately. Colony PCR was performed to screen for clones with inserts of correct sizes then sent for sequencing. IgBLAST from NCBI was used for the analysis of immunoglobulin variable domain sequences.145-99-1 VL: mouse IgK

[0113] VL Consensus Sequence starting from Frame 1 (FR1,), showing + strand.145-99-1 VH: mouse IgGl

[0114] VH Consensus Sequence starting from Frame 1 (FR1,), showing + strand.145-125-B VL: mouse IgK

[0115] VL Consensus Sequence starting from Frame 1 (FR1,), showing + strand145-125-B VH: mouse IgG2b

[0116] VH Consensus Sequence starting from Frame 1 (FR1,), showing + strandAnti-CD303-CAR-T generation and binding characterization to BPDCN in vitro

[0117] The CAR lentiviral constructs (MAb clones 145-99; 145-125, and 145-201), encoding anti-CD303 single-chain variable fragment (scFv), are transduced into T cells isolated from healthy donors’ PBMCs, and anti-CD303-CAR expression measured. The in vitro cytotoxicity ofPATENT DOCKET NO. MDA1380-1WOCAR-T cells labelled with CellTrace Violet are determined using CellTrace Far Red labelled CAL-1 and GEN2.2 human BPDCN cell lines, primary BPDCN samples and healthy BM cells.On-target anti-tumor activity of anti-CD303-CAR-T cells against BPDCN-PDX models in vivo.

[0118] CART efficacy in CD303 -expressing BPDCN PDX cells already generated, are study in the NSG murine models. Tumor burden are measured twice weekly by CD56+CD123+ flow cytometry, and CAR-T cell expansion by CD4 and CD8 subsets. The proliferation and exhaustion markers of anti-CD303 -CAR-T are monitored, and plasma cytokine / IFNg levels measured. Survival is followed and analyzed by Kaplan-Meyer curves.EXAMPLE 2GENE EXPRESSION OF CD303

[0119] Between 2010 and 2019, patients that fulfilled the diagnostic criteria for BPDCN were identified, as defined in the World Health Classification, with BM involvement. It has been shown that CD303 (BDCA2 / CLEC4C), was expressed in 44% (7 / 16) of cases suggesting high diagnostic value for BPDCN. CD303 is a soluble transmembrane glycoprotein, C-type lectin, a highly specific surface marker of human pDCs. A bioinformatic analysis was performed using online database Genotype-Tissue Expression (GTEx), which has shown undetectable gene expression of CD303 in most normal tissues, except for whole blood and spleen, and low expression in testis (FIG. 1). Thus, CD303 is an ideal target for MAb generation and development of CAR-T cell therapy for BPDCN.EXAMPLE 3GENERATION OF MABS ANTI-HUMAN CD303

[0120] Mouse anti-human CD303 MAbs were generated by hybridoma technology, using CT474 cell line, overexpressing CD303. Ten candidate clones were obtained, and specificity was confirmed by staining CAL-1 (CD303+ BPDCN cells line) compared to OCI-AML3 (negative control) (FIG. 2). Nine clones specifically recognized CD303+ / BPDCN cell lines. Mouse IgGl kappa isotype was included as a negative control. Alexa AffiniPure F(ab’) 2 fragment donkey antimouse IgG (H+L) was used as a secondary antibody.EXAMPLE 4DESIGN STRATEGY OF CD303 CART CONSTRUCTS AND CAR-T CELL GENERATION

[0121] CD303 CAR constructs were successfully generated. Briefly, out of nine clones that specifically recognized CD303+ / BPDCN cell lines, candidate CD303 Mab clones 145-99-1, 145-PATENT DOCKET NO. MDA1380-1WO125B, and 145-201A 99-1 were sequenced. The cDNA sequences of the single chain variable fragments (scFv) were cloned in a lentiviral vector pHR SFFV that includes CD8 and 0X40 signaling domains for CAR-T cell generation (FIGs.3A-3C). pHR SFFV-CD303-CAR lentivirus encoding two structural packaging plasmids were produced per published protocols.EXAMPLE 5VALIDATION ASSAY FOR SURFACE ANTI-CD303-CAR-T EXPRESSION AND CONFIRMATION

[0122] Jurkat-NFAT-Luc reporter cells were transduced with anti-CD303 -CAR-T lentiviral constructs. After 5 days, cells were harvested and incubated with his-Tag-CD303 protein peptide and CAR expression on the cell surface was confirmed using his-tagged CD303 recombinant protein (FIG. 4) conjugated with AF647. Cells were analyzed for GFP and AF637 by flow cytometry. Results shown in FIG. 5 confirm that the extracellular domain of all three scFv constructs on CD303-CAR-T cells, bind to recombinant his-CD303-AF647 protein.EXAMPLE 6ANTI-CD303-CAR-T CELLS GENERATION AND TARGET-SPECIFIC BINDING MODEL

[0123] It is critical to visualize and confirm the presence of scFv region from anti-CD303 antibody on CAR-T cells surface, to achieve optimal expression of antigen recognition domain, that preserves the specificity and affinity of the original variable regions (VH-VL) of antibody for its cognate antigen. It is also important to provide a measure of CAR transduction efficiency and to monitor and track the percentage of CAR+ levels to determine experimental setup for the effector:target ratios in the cytotoxicity functional studies in vitro and in vivo. After confirming anti-CD303-CAR expression (FIG. 5) a T cell activation-reporter assay was next performed. Briefly, Jurkat-Luc-NFAT-CD303 -CAR-T cells were co-cultured with BPDCN-positive and -negative cell lines (CAL-1 and OCI-AML3 respectively). CAL- 1 -triggered CAR-T cells activation was confirmed by the NFAT-luciferase secreted in the cell culture supernatants, detected by a Luminometer using Bright-Glo™ Luciferase Assay System (FIGs. 6A-6B).EXAMPLE 7TARGET-SPECIFIC EFFECTOR FUNCTIONAL ANALYSIS OF ANTI-CD303-CAR-T CELLS

[0124] The novel anti-CD303 -CAR-T cells showed T cells activation (FIG.6A) in all three CARs but higher in Jurkat-CD303-99-CAR-T cells co-cultured with BPDCN+ CAL-1 cells (usingPATENT DOCKET NO. MDA1380-1WOCD3 / CD28 as positive control). No luciferase was observed when control Jurkat-Lucia-NFAT cells were co-cultured with CAL-1 or OCI-AML3. All three CD303-CAR-T viral constructs are transduced into healthy CD3 enriched T cells from donors (n=5). Anti-CD303-CAR expression on cell surface are verified as shown in FIG. 5. Anti-CD303-CAR-T-cells with higher CD303 affinity are used for cytotoxic assays. Since BPDCN cells are highly BCL-2 dependent, pretreatment with BCL-2 inhibitor venetoclax further utilized prior to CART co-culture, in a subset of samples. BPDCN+CAL-1 cell line, primary samples (n=15) and normal bone marrow cells (n=3) are traced with CellTrace violet and co-cultured with CellTrace Far Red pre-stained effector CD303-CAR-T and mock-transduced control CAR-T cells at a 1:1, 3:1 or 10:1 effector-to-target ratio based on the results shown in FIG.7. After 4 days incubation, the viability of target cells are determined by flow cytometry. CD303 knock-out CAL-1 cell line, CD303 (-) OCLAML3 cells and CT474-CD303+reporter cells, serve as negative and positive controls, respectively. In addition to cytotoxicity, T-cell degranulation assays using CD 107a are analyzed by flow cytometry; and IFNyand cytokine production are analyzed in supernatants, using BioLegend LEGENDplex assay. The cytotoxic efficacy of anti-CD303 -CAR-T cells are determined by published cytotoxicity protocols.EXAMPLE 8FUNCTIONAL VALIDATION AND IDENTIFICATION OF LEAD CD303-CAR-T CELLS

[0125] BPDCN primary samples were banked and BPDCN patient derived xenografts (PDXs) established as described in Cai, T., et al., Targeting CD 123 in blastic plasmacytoid dendritic cell neoplasm using allogeneic anti-CD123 CAR T cells, Nat Commun 13, 2228 (2022), the content of which is herein incorporated by reference in its entirety. Primary BPDCN cells were collected from patients who had consented to research protocols. NOD SCID Gamma (NSG) mice are utilized in this study.BPDCN-PDX-luciferase reporter cell generation

[0126] Briefly, CD303+BPDCN PDX cells (n=3 models) are transduced with lentiviral vectors carrying both the firefly luciferase gene as well as GFP. GFP-sorted cells are used for in vivo validation. Eight- to 12-week-old mice are sub-lethally irradiated (250 cGy) 24 hours prior to injection. Then CD303+BPDCN PDX cells (n=3 models) are resuspended in the injection medium (serum-free RPMI1640) at a concentration of 2 x 106BPDCN cells / 100 pl. Cells are injected into NSG mice via the tail vein (100 ul / mouse). Firefly luciferase is used to track engraftment ofPATENT DOCKET NO. MDA1380-1WOBPDCN-Luc cells. Also, mice will be monitored weekly for evidence of human BPDCN-Luc cells IVIS imaging (IVIS-Xenogen 100 system) and CD56+CD303+CD123+ markers in peripheral blood samples using flow cytometry. Once circulating human BPDCN cells are detected at 1-3%, mice are randomized to treatment groups (5-10 mice per group). Treatments will comprise a single tail-vein injection of a) vehicle; b) control virus-transduced isogenic T cells; or c) 1, 3, or 10 x 109CD303-CAR-T cells per kilogram of body weight (the lead CAR-T cells identified from Aim- 1) as an adoptive transfer. Tumor burden is measured twice weekly by flow cytometry for CD56+CD123+cells. We will monitor the proliferation and exhaustion markers of anti-CD303 CAR using CD62L, CD45RA, CD4, CD3, CD8, PD-1, TIM-3, and CTLA-4 by flow cytometry. This will provide CAR-T cell peaking at 7-21 days after initial infusion and will be followed and monitored for another 3 weeks. Survival will be followed and analyzed using the Kaplan-Meier method. At the end of the study, localized BPDCN cells in BM are analyzed by flow cytometry for CD303, CD4, CD56, CD123, HLA-DR, TCL1, and TCF4. Levels of IFNyand cytokines in plasma are analyzed using BioLegend LEGEND plex kit. Mice are sacrificed when they show signs of suffering, weight loss, ruffling of hair or difficulties in movements, and when systemic BPDCN tumor cells exceed above 50% in circulation.In Vivo Bioluminescent Imaging (BLI)

[0127] Anesthetized mice are ip injected with D-luciferin (6 mg / mouse). Ten minutes later, imaging for BPDCN-luciferase expression are taken. Mice are placed into the light-tight chamber of an IVIS-100 BLI system. Mice’s photographs are acquired first for anatomical reference, followed by extended exposures (seconds to minutes) to acquire the BLI signal. Luminescence data is displayed in pseudocolor, superimposed on the photographs, and calibrated to units of radiance (photons s-lsr-lcm-2). Analysis and quantification are performed using Living image software 2.5.Anti-CD303-CAR-T tracking

[0128] Using flow cytometry, changes in the number of CAR-T cells in the presence of target cells are analyzed within 7 -21 days, after infusion and expansion, until 6 weeks post-infusion. Simultaneously, any mild to severe side effects from tumor burden and CAR-T infusion are investigated in the study cohorts.Statistical considerations

[0129] The endpoints of interest (e.g., BPDCN burden, CD3030+ cell removal) are compared among different cohorts. To compare the continuous endpoints (e.g., BPDCN burden), a t test or Mann- Whitney test for two-group comparisons, and analysis of variance or Kruskal-Wallis testPATENT DOCKET NO. MDA1380-1WOfor multiple-group comparisons are used. The primary endpoint is the reduction of BPDCN burden after the treatments. A sample size of 3 mice / group will have 80% power to detect an effect size of 3.04 using a significance level of 0.05. Overall survival is estimated using the Kaplan-Meier method and compared using the log-rank test. With a sample size of 7 mice in each group, there is 80% power to detect a hazard ratio of 0.193 between two groups at a significance level of 0.05 with a one-sided log-rank test. Incidence of recurrence is compared using Chi-squared test or Fisher’s exact test. Spearman correlation coefficient are used to correlate the expression of CD303 with reduction of tumor burden. Multiple comparisons are adjusted when appropriate.

[0130] List of sequencesDescription Sequence SEQ ID NO:145-99-1 CDRH1 GYTFTDFS 1145-99-1 CDRH2 INTETGEP 2145-99-1 CDRH3 GKDDYDRVAY 3145-99-1 CDRL1 QSVSTSSYGY 4145-99-1 CDRL2 YAS 5145-99-1 CDRL3 QHSWEIPYT 6145-99-1 IgGl VH QIQLVQSGPELKKPGETVKISCRASGYTFTDFSM 7HWVKQAPGKGLQWMGWINTETGEPTYADDFK GRFAFSLETSASTAYLQIINLKNEDTATYFCGKD DYDRVAYWGQGTLVTVSA145-99-1 IgK VL DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSY 8GYVHWYQQKPRQPPKLLIKYASNLESGVPARFS GSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYT FGGGTKLEIK145-125-B CDRH1 GFTFST 9145-125-B CDRH2 ISSGGST 10 145-125-B CDRH3 ARPSYDGYSSWFAY 11 145-125-B CDRL1 SQSVDYDGDGF 12 145-125-B CDRL2 TAS 13 145-125-B CDRL3 QQSNEDPWT 14PATENT DOCKET NO. MDA1380-1WO145-125-B VH EVKLVESGGGLVKPGGSLKLSCAASGFTFSTMS 15WVRQTPEKRLEWVASISSGGSTYYPDSVKGRFT ISRDNARNILYLQMSSLRSEDTAMYYCARPSYD GYSSWFAYWGQGTLVTVSA145-125-B VL DIVLTQSPASLAVSLGQRATISCKASQSVDYDG 16DGFMNWYQQKPGQPPKLLIYTASNLESGIPARF SGSGSGTDFTLNIHPVEEEDAATYYCQQSNEDP WTFGGGTKLEIK145-201A CDRH1 GFTFSSYT 17145-201A CDRH2 SSGGSYT 18 145-201A CDRH3 TRDRGDYDYDEGYYFDY 19145-201A CDRL1 ASVDSYGNSF 20145-201A CDRL2 LAS 21 145-201A CDRL3 QQNNEDPRT 22145-201AIgGl VH DVKLVESGGGLVKPGGSLNLSCAASGFTFSSYT 23MSWVRQNPEKRLEWVATISSGGSYTYYPDSVK GRFTISRDNAKNTLYLQMSSLKSEDTAMYYCTR DRGDYDYDEGYYFDYWGQGTTLTVSS145-201AIgK VL NIVLTQSPASLAVSLGQRATISCRASASVDSYGN 24SFMHWYQQKPGQPPKLLIYLASNLESGVPARFS GSGSRTDFTLTIDPVEADDAATYYCQQNNEDPR TFGGGTKLEIKLinker GGGGSGGGGSGGGGS, abbreviated as (GGGGS)325or (G4S)3

[0131] Although the invention has been described with reference to the above examples, it will be understood that modifications and variations are encompassed within the spirit and scope of the invention. Accordingly, the invention is limited only by the following claims.References1. Pemmaraju, N., et al. Tagraxofusp in Blastic Plasmacytoid Dendritic-Cell Neoplasm. N Engl J Med 380, 1628-1637 (2019).PATENT DOCKET NO. MDA1380-1WO2. Pemmaraju, N., et al. Long-Term Benefits of Tagraxofusp for Patients With Blastic Plasmacytoid Dendritic Cell Neoplasm. J Clin Oncol 40, 3032-3036 (2022).3. Pemmaraju, N. Novel Pathways and Potential Therapeutic Strategies for Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN): CD123 and Beyond. Curr Hematol Malig Rep 12, 510-512 (2017).4. Cai, T., et al. Targeting CD123 in blastic plasmacytoid dendritic cell neoplasm using allogeneic anti-CD123 CAR T cells. Nat Commun 13, 2228 (2022).5. Wang, W., et al. Immunophenotypic characterization of reactive and neoplastic plasmacytoid dendritic cells permits establishment of a 10-color flow cytometric panel for initial workup and residual disease evaluation of blastic plasmacytoid dendritic cell neoplasm. Haematologica 106, 1047-1055 (2021).6. Wilson, N.R., et al. CD303 (BDCA-2) - a potential novel target for therapy in hematologic malignancies. Leuk Lymphoma 63, 19-30 (2022).7. Bruggen, M.C., et al. Clinical diversity and treatment approaches to blastic plasmacytoid dendritic cell neoplasm: a retrospective multicentre study. J Eur Acad Dermatol Venereol 34, 1489-1495 (2020).8. Pagano, L., et al. Blastic plasmacytoid dendritic cell neoplasm with leukemic presentation: an Italian multicenter study. Haematologica 98, 239-246 (2013).9. Martin-Martin, L., et al. Blastic plasmacytoid dendritic cell neoplasm frequently shows occult central nervous system involvement at diagnosis and benefits from intrathecal therapy.Oncotarget 7 , 10174-10181 (2016).10. Grupp, S.A., et al. Chimeric antigen receptor-modified T cells for acute lymphoid leukemia. N Engl J Med 368, 1509-1518 (2013).11. Boiocchi, L., Lonardi, S., Vermi, W., Fisogni, S. & Facchetti, F. BDCA-2 (CD303): a highly specific marker for normal and neoplastic plasmacytoid dendritic cells. Blood 122, 296-297 (2013).12. Gamache-Ottou, F., et al. Extended diagnostic criteria for plasmacytoid dendritic cell leukaemia. Br J Haematol 145, 624-636 (2009).13. Okuma, A. Generation of CAR-T Cells by Lentiviral Transduction. Methods Mol Biol 2312, 3-14 (2021).14. Montero, J., et al. Blastic Plasmacytoid Dendritic Cell Neoplasm Is Dependent on BCL2 and Sensitive to Venetoclax. Cancer Discov 7, 156-164 (2017).PATENT DOCKET NO. MDA1380-1WO15. Cuglievan, B., et al. Blastic plasmacytoid dendritic cell neoplasm: a comprehensive review in pediatrics, adolescents, and young adults (AYA) and an update of novel therapies. Leukemia 37, 1767-1778 (2023).16. Kannan, S., et al. Antileukemia Effects of Notch-Mediated Inhibition of Oncogenic PLK1 in B-Cell Acute Lymphoblastic Leukemia. Mol Cancer Ther 18, 1615-1627 (2019).17. Chen, C.H., et al. Dendritic-cell-associated C-type lectin 2 (DCAL-2) alters dendritic-cell maturation and cytokine production. Blood 107, 1459-1467 (2006).18. Dzionek, A., et al. BDCA-2, a novel plasmacytoid dendritic cell-specific type II C-type lectin, mediates antigen capture and is a potent inhibitor of interferon alpha / beta induction. J Exp Med 194, 1823-1834 (2001).19. Kubota, S., et al. Lineage-specific RUNX2 super-enhancer activates MYC and promotes the development of blastic plasmacytoid dendritic cell neoplasm. Nat Commun 10, 1653 (2019). 20. Lontos, K., et al. Fully murine CD 105 -targeted CAR-T cells provide an immunocompetent model for CAR-T cell biology. Oncoimmunology 11, 2131229 (2022).821. Lanitis, E., et al. Optimized gene engineering of murine CAR-T cells reveals the beneficial effects of IL-15 coexpression. J Exp Med 218(2021).

Claims

PATENT DOCKET NO. MDA1380-1WOWhat is claimed is:

1. A monoclonal antibody or a fragment thereof that specifically binds to CD303 (BDCA2), comprising:a heavy chain variable region comprising:a CDRH1 comprising a sequence GYTFTDFS (SEQ ID NO: 1);a CDRH2 comprising a sequence INTETGEP (SEQ ID NO: 2);a CDRH3 comprising a sequence GKDDYDRVAY (SEQ ID NOG); and a light chain variable region comprising:a CDRL1 comprising a sequence QSVSTSSYGY (SEQ ID NO: 4); a CDRL2 comprising a sequence YAS (SEQ ID NO: 5); anda CDRL3 comprising a sequence QHSWEIPYT (SEQ ID NO: 6).

2. The monoclonal antibody of claim 1, comprising:the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWM GWINTETGEPTYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGK DDYDRVAYWGQGTLVTVSA (SEQ ID NO: 7); andthe light chain variable region sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKL LIKYASNLESGVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYT FGGGTKLEIK (SEQ ID NO: 8).

3. A monoclonal antibody or a fragment thereof that specifically binds to CD303 (BDCA2), comprising:the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWM GWINTETGEPTYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGK DDYDRVAYWGQGTLVTVSA (SEQ ID NO: 7); andthe light chain variable region sequence having 98% or greater identity to DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKL LIKYASNLESGVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYT FGGGTKLEIK (SEQ ID NO: 8).

4. The monoclonal antibody of any one of claims 1-3, comprising an IgGl heavy chain and a IgK light chain.

5. A chimeric antigen receptor (CAR) comprising an extracellular domain,PATENT DOCKET NO. MDA1380-1WOwherein the extracellular domain comprises a heavy chain variable region comprising:a CDRH1 comprising a sequence GYTFTDFS (SEQ ID NO: 1);a CDRH2 comprising a sequence INTETGEP (SEQ ID NO: 2);a CDRH3 comprising a sequence GKDDYDRVAY (SEQ ID NOG) ; and a light chain variable region comprising:a CDRL1 comprising a sequence QSVSTSSYGY (SEQ ID NO: 4);a CDRL2 comprising a sequence YAS (SEQ ID NO: 5); anda CDRL3 comprising a sequence QHSWEIPYT (SEQ ID NO: 6),wherein the extracellular domain targets CD303.

6. The CAR of claim 5, further comprising:a transmembrane domain, a linker and an intracellular domain,wherein the transmembrane domain comprises a CD8 hinge and a CD8 transmembrane domain;wherein the intracellular domain comprises one or more of an 0X40 costimulatory domain, a CD3z domain, a 4- IBB domain, and a CD28 domain; andwherein the linker comprises GGGGSGGGGSGGGGS (SEQ ID NO: 25).

7. The CAR of any one of claims 5-6, wherein the extracellular domain comprises:the heavy chain variable region sequence comprising the sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWM GWINTETGEPTYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGK DDYDRVAYWGQGTLVTVSA (SEQ ID NO: 7), andthe light chain variable region sequence comprising the sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKLLI KYASNLESGVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYTFGGG TKLEIK (SEQ ID NO: 8).

8. The CAR of claim 6, wherein the linker is located between the heavy chain variable domain and the light chain variable region.

9. A chimeric antigen receptor (CAR) comprising an extracellular domain,wherein the extracellular domain comprises a heavy chain variable region comprising the sequence ofPATENT DOCKET NO. MDA1380-1WOQIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWM GWINTETGEPTYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGK DDYDRVAYWGQGTLVTVSA (SEQ ID NO: 7); anda light chain variable region sequence having 98% or greater identity to the sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKL LIKYASNLESGVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYT FGGGTKLEIK (SEQ ID NO: 8),wherein the extracellular domain targets CD303 (BDCA2).

10. The CAR of claim 9, wherein the extracellular domain comprises:the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQWM GWINTETGEPTYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYFCGK DDYDRVAYWGQGTLVTVSA (SEQ ID NO: 7), andthe light chain variable region sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQPPKL LIKYASNLESGVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHSWEIPYT FGGGTKLEIK (SEQ ID NO: 8).

11. The CAR of any one of claims 9-10, further comprising:a transmembrane domain, a linker and an intracellular domain,wherein the transmembrane domain comprises a CD8 hinge and a CD8 transmembrane domain;wherein the intracellular domain comprises one or more of an 0X40 costimulatory domain, a CD3z domain, a 4- IBB domain, and a CD28 domain; andwherein the linker comprises (648)3 linker (SEQ ID NO: 25).

12. The CAR of claim 11, wherein the linker is located between the heavy chain variable domain and the light chain variable region.

13. A chimeric antigen receptor (CAR) comprising an extracellular domain,wherein the extracellular domain comprises a heavy chain variable region comprising:a CDRH1 comprising a sequence GFTFST (SEQ ID NO: 9);a CDRH2 comprising a sequence ISSGGST (SEQ ID NO: 10);a CDRH3 comprising a sequence ARPSYDGYSSWFAY (SEQ ID NO:11) ; and a light chain variable region comprising:PATENT DOCKET NO. MDA1380-1WOa CDRL1 comprising a sequence SQSVDYDGDGF (SEQ ID NO: 12); a CDRL2 comprising a sequence TAS (SEQ ID NO: 13); anda CDRL3 comprising a sequence QQSNEDPWT (SEQ ID NO: 14), wherein the extracellular domain targets CD303.

14. The CAR of claim 13, further comprising:a transmembrane domain, a linker and an intracellular domain,wherein the transmembrane domain comprises a CD8 hinge and a CD8 transmembrane domain;wherein the intracellular domain comprises one or more of an 0X40 costimulatory domain, a CD3z domain, a 4- IBB domain, and a CD28 domain; andwherein the linker comprises (648)3 (SEQ ID NO: 25) linker.

15. The CAR of any one of claims 13-14, wherein the extracellular domain comprises:the heavy chain variable region having the sequence of EVKLVESGGGLVKPGGSLKLSCAASGFTFSTMSWVRQTPEKRLEWVASI SSGGSTYYPDSVKGRFTISRDNARNILYLQMSSLRSEDTAMYYCARPSYD GYSSWFAYWGQGTLVTVSA (SEQ ID NO: 15),a light chain variable region sequence of DIVLTQSPASLAVSLGQRATISCKASQSVDYDGDGFMNWYQQKPGQPPK LLIYTASNLESGIPARFSGSGSGTDFTLNIHPVEEEDAATYYCQQSNEDPW TFGGGTKLEIK (SEQ ID NO: 16).

16. The CAR of claim 14, wherein the linker is located between the heavy chain variable domain and the light chain variable domain.

17. A dual chimeric antigen receptor (CAR) comprising a first CAR and a second CAR, wherein the first CAR the second CAR comprise an extracellular domain which is independently selected froma) an extracellular domain comprising a heavy chain variable region comprising:(i) a CDRH1 comprising a sequence GYTFTDFS (SEQ ID NO: 1);(ii) a CDRH2 comprising a sequence INTETGEP (SEQ ID NO: 2);(iii) a CDRH3 comprising a sequence GKDDYDRVAY (SEQ ID NOG);anda light chain variable region comprising:(i) a CDRL1 comprising a sequence QSVSTSSYGY (SEQ ID NO: 4);PATENT DOCKET NO. MDA1380-1WO(ii) a CDRL2 comprising a sequence YAS (SEQ ID NO: 5); and(iii) a CDRL3 comprising a sequence QHSWEIPYT (SEQ ID NO: 6); (b) an extracellular domain comprising a heavy chain variable region comprising:(i) a CDRH1 comprising a sequence GFTFST (SEQ ID NO: 9);(ii) a CDRH2 comprising a sequence ISSGGST (SEQ ID NO: 10);(iii) a CDRH3 comprising a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11); anda light chain variable region comprising:(i) a CDRL1 comprising a sequence SQSVDYDGDGF (SEQ ID NO:12);(ii) a CDRL2 comprising a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 comprising a sequence QQSNEDPWT (SEQ ID NO: 14);or(c) an extracellular domain comprising a heavy chain variable region comprising:(i) a CDRH1 comprising a sequence GFTFSSYT (SEQ ID NO: 17); (ii) a CDRH2 comprising a sequence SSGGSYT (SEQ ID NO: 18);(iii) a CDRH3 comprising a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19); anda light chain variable region comprising:(i) a CDRL1 comprising a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 comprising a sequence LAS (SEQ ID NO: 21); and (iii) a CDRL3 comprising a sequence QQNNEDPRT (SEQ ID NO: 22), wherein the extracellular domain of the first CAR and / or the second CAR targets CD303.

18. A dual chimeric antigen receptor (CAR) comprising a first CAR and a second CAR, wherein the extracellular domain of the first CAR and / or the second CAR is independently selected froma) an extracellular domain comprising the heavy chain variable region sequence of QIQLVQSGPELKKPGETVKISCRASGYTFTDFSMHWVKQAPGKGLQW MGWINTETGEPTYADDFKGRFAFSLETSASTAYLQIINLKNEDTATYF CGKDDYDRVAYWGQGTLVTVSA (SEQ ID NO: 7); andPATENT DOCKET NO. MDA1380-1WOthe light chain variable region sequence of DIVLTQSPASLAVSLGQRATVSCRASQSVSTSSYGYVHWYQQKPRQP PKLLIKYASNLESGVPARFSGSGSGTDFTLNIHPVEEEDTATYYCQHS WEIPYTFGGGTKLEIK (SEQ ID NO: 8);b) an extracellular domain comprising a heavy chain variable region sequence of EVKLVESGGGLVKPGGSLKLSCAASGFTFSTMSWVRQTPEKRLEWV ASISSGGSTYYPDSVKGRFTISRDNARNILYLQMSSLRSEDTAMYYCA RPSYDGYSSWFAYWGQGTLVTVSA (SEQ ID NO: 15), and a light chain variable region sequence of DIVLTQSPASLAVSLGQRATISCKASQSVDYDGDGFMNWYQQKPGQP PKLLIYTASNLESGIPARFSGSGSGTDFTLNIHPVEEEDAATYYCQQSN EDPWTFGGGTKLEIK (SEQ ID NO: 16); andc) an extracellular domain comprising a heavy chain variable region sequence of DVKLVESGGGLVKPGGSLNLSCAASGFTFSSYTMSWVRQNPEKRLE WVATISSGGSYTYYPDSVKGRFTISRDNAKNTLYLQMSSLKSEDTAM YYCTRDRGDYDYDEGYYFDYWGQGTTLTVSS (SEQ ID NO: 23); and a light chain variable region sequence of NIVLTQSPASLAVSLGQRATISCRASASVDSYGNSFMHWYQQKPGQP PKLLIYLASNLESGVPARFSGSGSRTDFTLTIDPVEADDAATYYCQQN NEDPRTFGGGTKLEIK (SEQ ID NO: 24).

19. A method of treating a disorder associated with plasmacytoid dendritic cells (pDC) in a subject in need thereof, comprising delivering to the subject a therapeutically effective amount of the antibody of any one of claims 1-4, the chimeric antigen receptor (CAR) of any one of claims 5-16, or the dual CAR of any one of claims 17-18,wherein the antibody, the CAR, or the dual CAR specifically binds to CD303 (BDCA2) and depletes pDC, thereby treating the disorder.

20. A method of treating a cancer expressing CD303 (BDCA2) in a subject comprising delivering to the subject a therapeutically effective amount of the antibody of any one of claims 1-4, the chimeric antigen receptor (CAR) of any one of claims 5-16, or the dual CAR of any one of claims 17-18,wherein the antibody, the CAR, or the dual CAR specifically binds to CD303 (BDCA2), thereby treating the cancer.PATENT DOCKET NO. MDA1380-1WO21. The method of any one of claims 19 or 20, wherein the method further comprises pretreatment of the subject with a BCL-2 inhibitor.

22. The method of claim 21, wherein the BCL-2 inhibitor is Venetoclax.

23. The method of any one of claims 19 or 20, wherein the cancer is blastic plasmacytoid dendritic cell neoplasm (BPDCN), acute myelogenous leukemia with clonal expansion of plasmacytoid dendritic cells (pDC-AML), breast cancer, oral squamous cell carcinoma, or non-small cell lung carcinoma.

24. A method of diagnosing a tumor with CD303 expression in a subject comprising detecting CD303 expression in the subject, comprising contacting the tumor with a monoclonal antibody that specifically binds to CD303,wherein the monoclonal antibody comprises:a) a heavy chain variable region comprising:(i) a CDRH1 comprising a sequence GYTFTDFS (SEQ ID NO: 1);(ii) a CDRH2 comprising a sequence INTETGEP (SEQ ID NO: 2);(iii) a CDRH3 comprising a sequence GKDDYDRVAY (SEQ ID NOG);anda light chain variable region comprising:(i) a CDRL1 comprising a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) a CDRL2 comprising a sequence YAS (SEQ ID NO: 5); and(iii) a CDRL3 comprising a sequence QHSWEIPYT (SEQ ID NO: 6); (b) a heavy chain variable region comprising:(i) a CDRH1 comprising a sequence GFTFST (SEQ ID NO: 9);(ii) a CDRH2 comprising a sequence ISSGGST (SEQ ID NO: 10);(iii) a CDRH3 comprising a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11) ; anda light chain variable region comprising:(i) a CDRL1 comprising a sequence SQSVDYDGDGF (SEQ ID NO:12);(ii) a CDRL2 comprising a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 comprising a sequence QQSNEDPWT (SEQ ID NO: 14);or(c) a heavy chain variable region comprising:(i) a CDRH1 comprising a sequence GFTFSSYT (SEQ ID NO: 17);PATENT DOCKET NO. MDA1380-1WO(ii) a CDRH2 comprising a sequence SSGGSYT (SEQ ID NO: 18); (iii) a CDRH3 comprising a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19); anda light chain variable region comprising:(i) a CDRL1 comprising a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 comprising a sequence LAS (SEQ ID NO: 21); and (iii) a CDRL3 comprising a sequence QQNNEDPRT (SEQ ID NO: 22); thereby diagnosing the tumor with CD303 expression in the subject.

25. A method of stratifying a subject with a tumor based on a CD303 expression, the method comprising contacting the tumor with a monoclonal antibody that specifically binds to CD303,wherein the monoclonal antibody comprises:a) a heavy chain variable region comprising:(i) a CDRH1 comprising a sequence GYTFTDFS (SEQ ID NO: 1); (ii) a CDRH2 comprising a sequence INTETGEP (SEQ ID NO: 2);(iii) a CDRH3 comprising a sequence GKDDYDRVAY (SEQ ID NOG);anda light chain variable region comprising:(i) a CDRL1 comprising a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) a CDRL2 comprising a sequence YAS (SEQ ID NO: 5); and(iii) a CDRL3 comprising a sequence QHSWEIPYT (SEQ ID NO: 6); b) a heavy chain variable region comprising:(i) a CDRH1 comprising a sequence GFTFST (SEQ ID NO: 9);(ii) a CDRH2 comprising a sequence ISSGGST (SEQ ID NO: 10); (iii) a CDRH3 comprising a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11); anda light chain variable region comprising:(i) a CDRL1 comprising a sequence SQSVDYDGDGF (SEQ ID NO:12);(ii) a CDRL2 comprising a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 comprising a sequence QQSNEDPWT (SEQ ID NO: 14);orc) a heavy chain variable region comprising:PATENT DOCKET NO. MDA1380-1WO(i) a CDRH1 comprising a sequence GFTFSSYT (SEQ ID NO: 17); (ii) a CDRH2 comprising a sequence SSGGSYT (SEQ ID NO: 18); (iii) a CDRH3 comprising a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19); anda light chain variable region comprising:(iv) a CDRL1 comprising a sequence ASVDSYGNSF (SEQ ID NO:20);(v) a CDRL2 comprising a sequence LAS (SEQ ID NO: 21); and (vi) a CDRL3 comprising a sequence QQNNEDPRT (SEQ ID NO: 22).

26. An antibody drug conjugate (ADC), comprising a monoclonal antibody that specifically binds to CD303,wherein the monoclonal antibody comprises:a) a heavy chain variable region comprising:(i) a CDRH1 comprising a sequence GYTFTDFS (SEQ ID NO: 1); (ii) a CDRH2 comprising a sequence INTETGEP (SEQ ID NO: 2);(iii) a CDRH3 comprising a sequence GKDDYDRVAY (SEQ ID NOG);anda light chain variable region comprising:(i) a CDRL1 comprising a sequence QSVSTSSYGY (SEQ ID NO: 4); (ii) a CDRL2 comprising a sequence YAS (SEQ ID NO: 5); and (iii) a CDRL3 comprising a sequence QHSWEIPYT (SEQ ID NO: 6); b) a heavy chain variable region comprising:(i) a CDRH1 comprising a sequence GFTFST (SEQ ID NO: 9);(ii) a CDRH2 comprising a sequence ISSGGST (SEQ ID NO: 10);(iii) a CDRH3 comprising a sequence ARPSYDGYSSWFAY (SEQ ID NO: 11) ; anda light chain variable region comprising:(i) a CDRL1 comprising a sequence SQSVDYDGDGF (SEQ ID NO:12);(ii) a CDRL2 comprising a sequence TAS (SEQ ID NO: 13); and (iii) a CDRL3 comprising a sequence QQSNEDPWT (SEQ ID NO: 14);orc) a heavy chain variable region comprising:PATENT DOCKET NO. MDA1380-1WOi) a CDRH1 comprising a sequence GFTFSSYT (SEQ ID NO: 17); ii) a CDRH2 comprising a sequence SSGGSYT (SEQ ID NO: 18); iii) a CDRH3 comprising a sequence TRDRGDYDYDEGYYFDY (SEQ ID NO: 19); anda light chain variable region comprising:(i) a CDRL1 comprising a sequence ASVDSYGNSF (SEQ ID NO: 20); (ii) a CDRL2 comprising a sequence LAS (SEQ ID NO: 21); and (iii) a CDRL3 comprising a sequence QQNNEDPRT (SEQ ID NO: 22).

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