Blinatumomab achieves tumour killing in relapsed B cell acute lymphoblastic leukemia by a mechanism best described as:
- A An antibody-drug conjugate delivering auristatin specifically to CD19-positive blasts
- B A bispecific tandem single-chain antibody linking CD19 on B cells to CD3 on T cells, forcing synapse formation and T cell mediated cytolysis ✓
- C A radiolabelled antibody delivering yttrium-90 to CD19-positive blasts
- D A complement-fixing IgM that lyses CD19-positive blasts directly
Correct answer: B. A bispecific tandem single-chain antibody linking CD19 on B cells to CD3 on T cells, forcing synapse formation and T cell mediated cytolysis
Explanation
Blinatumomab is a bispecific T cell engager (BiTE) with two antigen-binding domains joined by a flexible linker: one binds CD19 on malignant A cells, the other binds CD3 on cytotoxic T cells. This physically bridges the two cells, triggering perforin and granzyme mediated killing independent of MHC presentation. Antibody-drug conjugates such as brentuximab vedotin carry a payload, radioimmunoconjugates deliver isotopes, and complement fixation is the mechanism of rituximab-like IgG1 antibodies.
Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.