Camizestrant - (SERENA-6)

June 2, 2026: AstraZeneca (NYSE: AZN) reported updated Phase III SERENA-6 results (to be presented at the 2026 ASCO Annual Meeting, abstract LBA1007) evaluating switching, before progression, to camizestrant plus a CDK4/6 inhibitor (palbociclib, ribociclib or abemaciclib) versus continuing an aromatase inhibitor (anastrozole or letrozole) plus a CDK4/6 inhibitor after detection of an emergent ESR1 mutation in 1L HR-positive, HER2-negative advanced breast cancer.

With longer follow-up, the camizestrant combination maintained the PFS benefit and showed a statistically significant improvement in the key secondary endpoint PFS2. PFS: HR 0.45 (95% CI 0.34–0.59; p<0.00001), median 16.8 vs 9.2 months. Final PFS2: HR 0.63 (95% CI 0.46–0.86; p=0.00373), median 25.7 vs 19.1 months. OS showed a numerical trend (HR 0.87; 30% maturity); trial continues to final OS analysis.

Exploratory analyses: median total ctDNA change at week 8 was -99% with camizestrant vs +64% with standard of care; total ctDNA clearance 51% (50/98) vs 1.9% (2/108). Chemotherapy/ADC-free survival: 22.6 vs 18.7 months (HR 0.64; p=0.00375). Safety showed no new concerns.

Regulatory: camizestrant is approved in the UAE and Saudi Arabia; EMA CHMP adopted a positive opinion for EU approval; applications are under review in the US, Japan and other countries, and FDA recently extended the PDUFA date to review the updated SERENA-6 results.