AstraZeneca Breast Cancer Trial Misses Key Goal

AstraZeneca said its breast cancer pill camizestrant, or Etcamah, failed to significantly improve progression-free survival in the late-stage SERENA-4 trial when combined with Pfizer’s Ibrance in previously untreated patients with advanced hormone-receptor-positive, HER2-negative breast cancer. The study enrolled 1,371 patients and compared the combination with Ibrance plus hormone-suppressing therapy, sending AstraZeneca shares lower in after-hours trading. The result contrasts with the drug’s recent accelerated FDA approval for a narrower group of patients whose tumors develop an ESR1 mutation after initial treatment; in the SERENA-6 trial, camizestrant reduced the risk of progression or death by 56%. Analysts described the failed broader trial as a setback but not necessarily a threat to camizestrant’s longer-term prospects, with full data still expected at a medical conference.