AstraZeneca's Phase 3 Trial of Combination Treatment for Breast Cancer Fails to Meet Primary Endpoint

11:23 PM EDT, 09/13/2026 (MT Newswires) -- AstraZeneca (AZN.L, AZN.ST) reported on Sept. 11 that the Serena-4 phase 3 trial of Etcamah, or camizestrant, plus palbociclib failed to meet the primary endpoint of progression-free survival in patients with estrogen receptor-positive, HER2-negative advanced breast cancer. The trial compared the combination formulation against a treatment comprising the aromatase inhibitor anastrozole and palbociclib. The pharmaceutical company said the study exhibited a numerical improvement in the upfront first-line treatment. The company also reported that the safety profile of the tested combination formulation was in line with known profiles for each component, with no new safety concerns determined during the trial.