A 58-year-old man with metastatic colorectal carcinoma has a tumour biopsy showing a mutation in KRAS codon 12. First-line combination chemotherapy is planned. Which of the following agents is an appropriate addition to his regimen?
- A Bevacizumab ✓
- B Panitumumab
- C Cetuximab
- D Nivolumab
Correct answer: A. Bevacizumab
Explanation
Activating KRAS mutations render downstream signalling constitutively active, so antibodies against EGFR such as cetuximab and panitumumab confer no benefit and are contraindicated. Bevacizumab acts on VEGF-C, a pathway independent of KRAS status, and is appropriate first-line. Nivolumab is an option in MSI-high refractory disease, not first-line microsatellite-stable disease, making it the tempting but incorrect distractor here.
Reference: DeVita, Hellman, and Rosenberg's Cancer: Principles and Practice of Oncology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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