Pfizer Inc. (NYSE: PFE) reported that its drug combination of TALZENNA and XTANDI reduced the risk of radiographic progression or death by 52% compared to placebo plus XTANDI in men with metastatic hormone-sensitive prostate cancer with specific gene mutations.

The Phase 3 TALAPRO-3 study showed a hazard ratio of 0.48 for the combination treatment, with results presented at the American Society of Clinical Oncology Annual Meeting and published in The New England Journal of Medicine.

At three years, 77% of patients treated with the combination remained progression-free versus 56% of patients on placebo plus XTANDI. After more than 37 months of follow-up, median radiographic progression-free survival was not reached in the combination arm and was 46 months with placebo and XTANDI.

The study enrolled 599 patients with metastatic castration-sensitive prostate cancer harboring homologous recombination repair gene alterations. The treatment benefit was consistent across patients with both BRCA and non-BRCA gene alterations.

The most common adverse events in the combination group were anemia, fatigue, decreased neutrophil count, and weakness. Grade 3 or higher anemia occurred in 51% of combination patients versus 3% in the control group. Five percent of patients discontinued TALZENNA due to anemia.

TALZENNA plus XTANDI is currently approved in more than 60 countries for metastatic castration-resistant prostate cancer. Pfizer stated it will discuss these new results with global health authorities to potentially expand the indication to the earlier disease stage studied in TALAPRO-3.