AstraZeneca’s Camizestrant Shows Major Breakthrough in Breast Cancer Treatment

AstraZeneca’s experimental pill camizestrant significantly reduced the risk of disease progression or death in hormone receptor-positive, HER2-negative breast cancer, according to new data presented at the American Society of Clinical Oncology (ASCO) meeting. In the trial, patients switched to camizestrant after early signs of resistance detected through a blood-based liquid biopsy showed a 56% improvement in progression-free survival compared to standard therapy.

This marks the first time liquid biopsy has been used to guide treatment decisions before visible tumor growth. Dr. Eleonora Teplinsky of Valley-Mount Sinai said the early switch approach allows oncologists to “stay ahead of the curve,” potentially changing how breast cancer is treated.

The phase 3 study enrolled 3,256 women with advanced HR-positive, HER2-negative breast cancer. After at least six months of aromatase inhibitors and CDK4/6 inhibitors—like Kisqali (Novartis), Ibrance (Pfizer), or Verzenio (Eli Lilly)—315 patients with ESR1 mutations were identified and randomized. Patients receiving camizestrant plus a CDK4/6 inhibitor saw a median of 16 months without disease progression, versus 9.2 months on standard therapy with placebo.

No new safety issues were reported, and dropout rates remained low. Camizestrant is a selective estrogen receptor degrader (SERD), designed to block estrogen signaling in cancer cells—an alternative when standard hormone therapies lose effectiveness.

In a separate trial, AstraZeneca’s immunotherapy Imfinzi (durvalumab), combined with FLOT chemotherapy, reduced the risk of disease recurrence or death by 29% in early-stage gastric and esophageal cancer patients. The findings support earlier intervention with immunotherapy and are expected to influence global treatment practices.

AstraZeneca CEO Pascal Soriot emphasized the importance of proactive monitoring, calling it the future of cancer care. Both studies were simultaneously published in the New England Journal of Medicine.