FDA Approves Camizestrant Combo for ESR1 Mutated Breast Cancer

The FDA has granted accelerated approval to camizestrant (brand name Etcamah), an estrogen receptor antagonist, for use with a CDK4/6 inhibitor (abemaciclib, palbociclib, or ribociclib) in adults with HR positive, HER2 negative locally advanced or metastatic breast cancer whose tumors develop an ESR1 mutation while on an aromatase inhibitor plus a CDK4/6 inhibitor, according to the FDA's announcement. The agency also approved the Guardant360 CDx blood test as a companion diagnostic to detect the mutation.

The approval rests on SERENA6, a randomized, blinded, placebo controlled trial of 315 patients who switched to camizestrant plus their existing CDK4/6 inhibitor versus continuing the aromatase inhibitor combination. Median progression free survival was 16 months in the camizestrant arm compared with 9.2 months in the control arm. Overall survival data were not yet mature at the time of analysis.

Camizestrant carries a boxed warning for arrhythmia risk tied to QTc prolongation, along with warnings for bradycardia and embryo fetal toxicity. Because this is an accelerated approval, continued marketing depends on confirmatory trials verifying clinical benefit. This is a real, FDA authorized treatment for a specific mutation, not a general breast cancer therapy, and any use outside its approved indication should be guided by an oncologist.

This article is for education only. It is not medical advice. Compounds discussed here are sold for research purposes. Talk to a licensed clinician before making health decisions.