Obinutuzumab shows superior progression-free survival compared with rituximab in chronic lymphocytic leukaemia when combined with chlorambucil. The pharmacological property responsible for this advantage is:

• A It is a fully human antibody with lower immunogenicity
• B It directly blocks the B-cell receptor signalling pathway like ibrutinib
• C It binds CD20 more abundantly because it recognises a larger epitope loop
• D It is a type II, glycoengineered anti-CD20 antibody with enhanced antibody-dependent cellular cytotoxicity ✓

Explanation

Obinutuzumab is a glycoengineered (low-fucose Fc) type II anti-CD20 antibody. Reduced fucosylation increases Fc-gamma-RIIIa binding on natural killer cells, markedly enhancing antibody-dependent cellular cytotoxicity, and type II antibodies induce stronger direct cell death and less complement activation or cap formation than type I antibodies such as rituximab. It remains chimeric-humanized rather than fully human, and it does not inhibit BTK signalling, which is the mechanism of ibrutinib.

Reference: Williams Hematology, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.