Bispecific antibody-like binding proteins specifically binding to cd3 and cd123

An antibody-like binding protein that binds specifically to human CD3ε and human CD123 comprising three polypeptide chains that form two antigen-binding sites, wherein a first polypeptide has a structure represented by the formula [I]:

• VD1-L1-VD2-L2-CL [I]
• and a second polypeptide chain has a structure represented by the formula [III]:
• VD3-L3-VD4-L4-CH1-Fc [III];
• and a third polypeptide Fc3 which is the immunoglobulin hinge region and CH2, CH3 immunoglobulin heavy chain constant domains of an immunoglobulin;
• wherein
• c) said polypeptide of formula [I] consists of:
• (iii) the amino acid sequence SEQ ID NO:
• 55 which comprises
• VD1 of sequence SEQ ID NO:
• 54,
• L1 of sequence SEQ ID NO:
• 56,
• VD2 of sequence SEQ ID NO:
• 10,
• L2 of sequence SEQ ID NO:
• 56,
• CL of sequence SEQ ID NO:
• 18,
• or
• (iv) a sequence at least 85% identical to SEQ ID NO:
• 55 in which
• the 3 CDRs of sequences SEQ ID NO:
• 48, ‘WAS’ and SEQ ID NO:
• 49 of VD1 of sequence SEQ ID NO:
• 54, are unaltered and
• the 3 CDRs of sequences SEQ ID NO:
• 11, ‘KVS’ and SEQ ID NO:
• 8 of VD2 of sequence SEQ ID NO:
• 10 are unaltered;
• d) said polypeptide of formula [III] consists of:
• (iii) the amino acid sequence SEQ ID NO:
• 67 which comprises:
• VD3 of sequence SEQ ID NO:
• 9,
• L3 which consists of 0 amino acid,
• VD4 of sequence SEQ ID NO:
• 52,
• L4 which consists of 0 amino acid,
• CH1 of sequence SEQ ID NO:
• 19, and
• Fc of sequence SEQ ID NO:
• 68 wherein X1 is Y, X2 is C, X3 is W, X4 is L, X5 is Y, and X6 is H and X7 is Y, or X6 is R and X7 is F,
• or
• (iv) a sequence at least 85% identical to SEQ ID NO:
• 67 in which
• the 3 CDRs of sequences SEQ ID NO:
• 50, SEQ ID NO:53, and SEQ ID NO:
• 51 of VD4 of sequence SEQ ID NO:
• 52, are unaltered and
• the 3 CDRs of sequences SEQ ID NO:
• 5, SEQ ID NO:
• 6, SEQ ID NO:
• 7 of VD3 of sequence SEQ ID NO:
• 9 are unaltered, and
• the amino acids X1, X2, X3, X4, X5, X6 and X7 are as defined above in b)(i),
• and wherein:
• the polypeptide formula [I] and the polypeptide of formula [III] form a cross-over light chain-heavy chain pair,
• the polypeptide of formula [III] heterodimerizes with the third polypeptide through its Fc domain
• said third polypeptide F3 consists of SEQ ID NO:
• 69 or a sequence at least 85% identical to SEQ ID NO:
• 69, wherein the amino acid positions 129, 146, 148, 187, 215, 216 of SEQ ID NO:
• 69 are unaltered.