Pfizer Inc. (NYSE: PFE) announced that its Phase 3 TALAPRO-3 study met its primary endpoint, showing TALZENNA (talazoparib) plus XTANDI (enzalutamide) significantly improved radiographic progression-free survival compared to placebo plus XTANDI in patients with homologous recombination repair gene-mutated metastatic castration-sensitive prostate cancer.

The study enrolled 599 patients across the U.S., Canada, Europe, South America, and Asia-Pacific. Results exceeded the pre-specified target hazard ratio of 0.63, with most patients remaining progression-free at the time of analysis. The combination showed consistent benefits in patients with both BRCA and non-BRCA HRR gene alterations.

An interim analysis showed a trend toward improved overall survival, a key secondary endpoint. Other secondary endpoints showed benefits including overall response rate, duration of response, and time to prostate-specific antigen progression. The safety profile remained consistent with known profiles of each medicine, with no new safety signals identified.

TALZENNA plus XTANDI is currently approved in 60 countries for HRR gene-mutated metastatic castration-resistant prostate cancer. The companies plan to discuss these results with global health authorities for potential regulatory submissions to expand the indication to earlier-stage disease.

HRR gene alterations are found in approximately 25% of metastatic prostate cancers and are associated with worse prognosis and reduced response to current treatments. Despite recent advances, 50% to 65% of patients with metastatic castration-sensitive prostate cancer progress to castration-resistant disease within two years.

The study results will be submitted for presentation at an upcoming medical congress, according to the company's press release.