Atezolizumab is distinguished from nivolumab by which feature?
- A It is a small molecule kinase inhibitor rather than a monoclonal antibody
- B It binds CTLA-4 instead of the PD-1 axis
- C It binds PD-L1 and therefore also blocks PD-L1 binding to B7.1 on antigen-presenting cells ✓
- D It requires intratumoural injection unlike systemic PD-1 antibodies
Correct answer: C. It binds PD-L1 and therefore also blocks PD-L1 binding to B7.1 on antigen-presenting cells
Explanation
Atezolizumab is an anti-PD-L1 antibody, so it blocks interaction of PD-L1 with both PD-1 on T cells and B7.1 (CD80) on antigen-presenting cells, whereas nivolumab and pembrolizumab bind PD-1 on the T cell itself. It remains a fully human monoclonal antibody given systemically. Durvalumab and avelumab are the other anti-PD-L1 agents.
Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.
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