CD20-binding polypeptide compositions and methods

A CD20-binding polypeptide composition comprising a combination of a modified heavy chain variable region polypeptide and a modified ht chain variable region polypeptide, the combination being selected from the group consisting of:

• (a) a combination of a modified 2B8 antibody heavy chain variable region polypeptide having the amino acid residue sequence of SEQ ID NO:
• 48 and which includes at least one of the following amino acid residues:
• K at residue 12, P at residue 14, V at residue 20, T at residue 48, T at residue 68, E at residue 82, R at residue 87, T at residue 91, and W at residue 106;
• and a modified 2B8 antibody light chain variable region polypeptide having the amino acid residue sequence of SEQ ID NO:
• 49 and which includes at least one of the following amino acid residues:
• I at residue 11, T at residue 12, T at residue 27, A at residue 29, T at residue 40, S at residue 59, T at residue 69, M at residue 72, S at residue 76, and L at residue 77;
• and
• (b) a combination of a modified Leu16 antibody heavy chain variable region polypeptide having the amino acid residue sequence of SEQ ID NO:
• 50 and which includes at least one of the following amino acid residues:
• K at residue 12, V at residue 20, T at residue 68, E at residue 82, Rat residue 87, T at residue 91, V at residue 93, and T at residue 114;
• and a modified Leu16 antibody light chain variable region polypeptide having the amino acid residue sequence of SEQ ID NO:
• 51 and which includes at least one of the following amino acid residues:
• I at residue 11, T at residue 12, S at residue 59, T at residue 69, M at residue 72, S at residue 76, and L at residue 77.