An acneiform papulopustular rash developing within the first two weeks of cetuximab therapy correlates with which clinical outcome?

• A Better tumour response and survival ✓
• B Development of a second primary malignancy
• C Impending anaphylaxis on subsequent infusions
• D Emergence of EGFR kinase domain mutations

Explanation

EGFR is expressed in basal keratinocytes and follicular epithelium, so EGFR inhibition produces an acneiform rash in a large majority of patients. Multiple studies show that patients who develop the rash have higher response rates and better survival than those who do not, making it a pharmacodynamic marker of target engagement. It does not predict infusion reactions, which relate to the murine component and occur during administration, nor does it reflect acquired resistance mutations.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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