Compositions and methods for immunotherapy targeting flt3, pd-1, and/or pd-l1

An antibody or an antigen binding fragment thereof or a polypeptide comprising either or both of:

• (i) a single chain variable fragment sequence (scFv) comprising an amino acid sequence of (Q V Q L V Q S G V E V K K P G A S V K V S C K A S G Y T F T N Y Y M Y W V R Q A P G Q G L E W M G G I N P S N G G T N F N E K F K N R V T L T T D S S T T T A Y M E L K S L Q F D D T A V Y Y C A R R D Y R F D M G F D Y W G Q G T T V T V S S G G G G S G G G G S G G G G S D I Q M T Q S P S S L S A S V G D R V T I T C R A S Q D V S T A V A W Y Q Q K P G K A P K L L I Y S A S F L Y S G V P S R F S G S G S G T D F T L T I S S L Q P E D F A T Y Y C Q Q Y L Y H P A T F G Q G T K V E I K R (SEQ ID NO:
• 13) or an equivalent thereof, optionally encoded by the nucleotide sequence comprising a nucleic acid sequence (CAGGTCCAATTGGTACAGAGCGGCGTCGAAGTAAAGAAGCCTGGAGCCAGCGTTA AAGTTTCTTGCAAGGCTTCAGGATATACTTTCACTAACTACTATATGTACTGGGTAC GGCAGGCTCCAGGGCAAGGGTTGGAGTGGATGGGAGGGATCAATCCTTCTAACGGC GGCACTAACTTTAACGAAAAATTTAAAAATAGGGTGACCCTCACAACTGACTCAAG TACGACTACAGCATACATGGAACTCAAATCTCTCCAATTCGATGACACGGCTGTCTA TTATTGCGCGAGAAGAGACTATCGCTTCGATATGGGGTTTGATTATTGGGGGCAAGG TACTACGGTTACCGTCAGCTCCGGGGGTGGCGGCTCCGGCGGCGGTGGGTCAGGTG GAGGAGGGTCTGACATTCAGATGACGCAATCCCCAAGCTCTCTGTCCGCGTCAGTGG GCGACCGAGTTACAATCACATGCCGCGCTTCTCAAGATGTGTCAACCGCTGTCGCCT GGTACCAACAGAAGCCTGGGAAGGCCCCTAAGCTTCTCATCTACTCAGCTTCTTTTC TGTACTCAGGGGTACCGTCTAGATTCTCAGGATCCGGTAGTGGGACGGACTTCACAT TGACCATAAGTTCCTTGCAGCCTGAGGATTTCGCTACATATTATTGCCAACAGTACC TTTACCATCCTGCCACTTTTGGCCAGGGTACTAAGGTCGAGATCAAACGG (SEQ ID NO:
• 14)), or an equivalent thereof;
• or
• (ii) a scFv comprising an amino acid sequence (EVQLVESGGGLVQPGGSLRLSCAASGFTFSDSWIHWVRQAPGKGLEWVAWISPYGGST YYADSVKGRFTISADTSKNTAYLQMNSLRAEDTAVYYCARRHWPGGFDYWGQGTLVT VSAGGGGSGGGGSGGGGSEIVLTQSPATLSLSPGERATLSCRASKGVSTSGYSYLHWYQ QKPGEAPRLLIYLASYLESGVPARFSGSGSGTDFTLTISSLEPEDFAVYYCQHSRDLPLTF GGGTKVEIK (SEQ ID NO:
• 15)) or an equivalent thereof, optionally encoded by the nucleotide sequence:
• (GAAGTTCAGTTGGTCGAGTCAGGAGGAGGCCTGGTGCAACCCGGGGGCT
• CACTCCGGTTGTCCTGTGCTGCTTCAGGATTTACGTTTTCTGACTCATGG
• ATACATTGGGTGCGCCAAGCCCCGGGCAAGGGGCTGGAATGGGTGGCCTG
• GATCTCTCCGTATGGGGGTTCCACCTACTATGCTGATTCAGTAAAAGGAC
• GGTTCACTATAAGCGCGGATACAAGTAAGAATACTGCCTATCTTCAAATG
• AATTCTCTTCGCGCCGAGGATACAGCGGTATATTATTGCGCTAGACGACA
• TTGGCCAGGGGGCTTTGACTATTGGGGGCAGGGTACTCTTGTGACCGTTA
• GTGCGGGAGGTGGTGGCAGCGGTGGAGGCGGCTCCGGGGGTGGTGGTTCA
• GAAATTGTCCTGACTCAATCCCCTGCCACATTGAGTTTGAGCCCAGGAGA
• GAGAGCAACTCTGTCATGCCGGGCGTCAAAAGGTGTCAGTACGTCAGGCT
• ACTCCTATCTTCATTGGTATCAGCAGAAACCGGGAGAAGCGCCGCGCCTT
• CTCATATACCTGGCTAGTTACCTTGAGAGTGGCGTCCCGGCCCGGTTTAG
• TGGGAGTGGGTCTGGGACTGATTTTACGCTGACAATCAGCAGTCTTGAGC
• CAGAGGACTTCGCGGTTTACTATTGCCAACATTCACGCGATTTGCCCCTC
• ACCTTCGGCGGTGGAACGAAGGTTGAAATAAAA (SEQ ID NO:
• 16)), or an equivalent thereof.