Pfizer Reports Results From Phase 3 HER2CLIMB-05 Trial, TUKYSA, Trastuzumab, And Pertuzumab Cuts Risk of Disease Progression or Death by 36% in Phase 3 HER2+ Metastatic Breast Cancer Study

• TUKYSA, trastuzumab, and pertuzumab reduced the risk of disease progression or death by 36% compared to trastuzumab and pertuzumab alone in Phase 3 HER2CLIMB-05 study
• The combination demonstrated a manageable safety profile as a first-line maintenance therapy

Pfizer Inc. (NYSE:PFE) today announced detailed results from the Phase 3 HER2CLIMB-05 trial of the tyrosine kinase inhibitor TUKYSA® (tucatinib) as part of an investigational first-line maintenance treatment combination, following chemotherapy-based induction, in patients with human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer (MBC). The primary endpoint analysis showed a 35.9% reduction in the risk of disease progression or death among patients treated with TUKYSA, trastuzumab, and pertuzumab compared to those treated with placebo, trastuzumab, and pertuzumab, as assessed by the investigator (hazard ratio [HR] of 0.641, 95% confidence interval (CI): 0.514-0.799; 2-sided p<0.0001). These findings were published today in the Journal of Clinical Oncology, shared in an oral presentation at the 48th San Antonio Breast Cancer Symposium (SABCS), and highlighted in the SABCS official press program.

In HER2CLIMB-05, the median progression-free survival (PFS) was 24.9 months (95% CI: 21.3-not reached) in the TUKYSA arm and 16.3 months (95% CI:12.6-18.7) in the placebo arm, representing an extension in median PFS of 8.6 months. A PFS benefit was observed across all prespecified patient subgroups, including de novo or recurrent diagnosis, hormone receptor (HR)-positive or HR-negative disease, and with or without the presence or history of brain metastases at baseline. The key secondary endpoint of overall survival was not mature at the time of the analysis (20% of the required events have occurred to date) but showed a numerical trend for improvement with TUKYSA.