Pfizer (NYSE:PFE) today announced positive topline results from its Phase 3 TALAPRO-3 study, evaluating the combination of TALZENNA® (talazoparib) and XTANDI® (enzalutamide).
The trial focused on patients with homologous recombination repair (HRR) gene-mutated metastatic castration-sensitive prostate cancer (mCSPC).
The study successfully met its primary endpoint, showing a statistically significant and clinically meaningful improvement in radiographic progression-free survival (rPFS) compared to the control group receiving placebo plus XTANDI.
The results notably exceeded the pre-specified target hazard ratio of 0.63, with Pfizer reporting that a majority of patients remained progression-free at the time of the analysis.
The efficacy was consistent across both BRCA and non-BRCA HRR gene alterations, a critical finding given that these mutations—found in approximately 25% of metastatic prostate cancers—are typically associated with a poorer prognosis and lower responsiveness to existing standards of care.
Beyond the primary endpoint, the interim analysis revealed a strong trend toward improved overall survival (OS), a key secondary metric.
Other secondary benefits observed included higher overall response rates, increased duration of response, and a delayed time to Prostate-Specific Antigen (PSA) progression.
The safety profile of the combination therapy was also consistent with the established profiles of the individual medicines, with no new safety signals identified during the trial.