Breast Cancer Drug Wins Approval Despite Rejection by Agency Advisors

The FDA granted accelerated approval to camizestrant (Etcamah) combined with a CDK4/6 inhibitor in adults with HR-positive, HER2-negative advanced breast cancer in whom an ESR1 mutation is detected in ctDNA during aromatase inhibitor plus CDK4/6 inhibitor therapy. The basis is the phase 3 SERENA-6 trial (n=315), where switching therapy on mutation detection extended progression-free survival from 9.2 to 16.0 months (HR 0.44; 95% CI 0.31-0.60). This is the first approval of a cancer therapy guided by detection of a resistance mutation in ctDNA before progression is visible on imaging. The approval is accelerated and rests on a progression-free survival endpoint; the FDA advisory committee had voted against granting it.