AstraZeneca (AZ) has secured US accelerated approval for camizestrant (Etcamah), a next-generation oral selective oestrogen receptor degrader (SERD), for HR-positive, HER2-negative, locally advanced or metastatic breast cancer with ESR1 mutation detected by an approved test during aromatase inhibitor plus CDK4/6 inhibitor therapy. The decision rests on SERENA-6, the first registrational double-blind Phase III trial to use circulating tumour DNA monitoring to switch therapy before radiographic progression: camizestrant plus a CDK4/6 inhibitor cut progression or death risk by 56% versus continued aromatase inhibitor plus CDK4/6 inhibitor (median PFS 16.0 versus 9.2 months, HR 0.44, p<0.00001), with a later prespecified analysis showing PFS2 of 25.7 versus 19.1 months (HR 0.63, p=0.00373) and an immature but favourable overall survival trend (HR 0.87).

Camizestrant's differentiation is twofold – oral dosing and ESR1-mutation targeting versus fulvestrant's intramuscular delivery and Menarini's elacestrant, which already holds an ESR1-mutant label but with a narrower PFS delta – and the ctDNA-guided SERENA-6 design sets a regulatory precedent for switch-maintenance trials in endocrine-resistant disease.

Safety matched known CDK4/6 inhibitor profiles with no new signals and low discontinuation, supporting combination use with palbociclib, ribociclib, or abemaciclib.