Blinatumomab is approved for relapsed/refractory precursor B cell acute lymphoblastic leukaemia. Its distinguishing pharmacological feature compared with conventional monoclonal antibodies is:

• A It inhibits the proteasome, causing accumulation of pro-apoptotic proteins in leukaemic cells
• B It is a conjugate of an anti-CD22 antibody with calicheamicin, releasing DNA-damaging toxin inside the blast
• C It blocks the interleukin-2 receptor alpha chain to starve blasts of growth signals
• D It is a bispecific T cell engager linking CD19 on blasts to CD3 on T cells, forcing a cytolytic synapse ✓

Explanation

Blinatumomab is a bispecific single-chain antibody construct with one arm binding CD19 on B lineage blasts and the other binding CD3 on cytotoxic T cells, physically bridging them so the T cell kills the tumour independently of MHC presentation. Because activated T cells flood the patient with cytokines, life-threatening cytokine release syndrome and neurotoxicity occur, requiring step-up dosing. Inotuzumab ozogamicin matches option B, and option A describes bortezomib.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.