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Mar 17, 2026 12:00 PM

Pfizer Touts Promising Survival Data Without Worsening For Advanced Breast Cancer Patients

Pfizer Inc. (NYSE:PFE) on Tuesday announced topline results from the Phase 2 FOURLIGHT-1 study in pretreated metastatic breast cancer patients.

The trial, which included 264 patients with HR-positive, HER2-negative advanced or metastatic breast cancer, evaluated atirmociclib in combination with fulvestrant versus fulvestrant or everolimus plus exemestane for second-line treatment.

The study met its primary endpoint, showing a significant improvement in progression-free survival (PFS), consistent across all prespecified subgroups. Over 90% of patients started atirmociclib within three months of their last CDK4/6 inhibitor treatment.

Overall Survival Data Still Maturing

Overall survival (OS) data remains immature, with about 20% of participants experiencing an event. Atirmociclib was well tolerated, with ...