Pfizer announced positive topline results from the Phase 3 TALAPRO-2 study of TALZENNA (talazoparib), an oral poly ADP-ribose polymerase (PARP) inhibitor, in combination with XTANDI (enzalutamide) compared to placebo plus XTANDI in men with metastatic castration-resistant prostate cancer (mCRPC), with or without homologous recombination repair (HRR) gene mutations.

The study met its primary endpoint with a statistically significant and clinically meaningful improvement in radiographic progression-free survival (rPFS) compared with placebo plus XTANDI. The results of the primary endpoint exceeded the pre-specified hazard ratio of 0.696.

Results showed a trend toward improved overall survival, a key secondary endpoint, at the time of the analysis, but these data are not yet mature. Benefits were also observed in other secondary endpoints, including investigator assessed rPFS, prostate specific antigen (PSA) response, time to PSA progression, and overall response rate. Other secondary endpoints are being analyzed. At the time of topline analysis, the safety of TALZENNA plus XTANDI were generally consistent with the known safety profile of each medicine.

“XTANDI is a global standard of care, with overall survival demonstrated in mCRPC, non-metastatic CRPC, and metastatic castration-sensitive prostate cancer (mCSPC),” said Chris Boshoff, M.D., Ph.D., Chief Development Officer, Oncology and Rare Disease, Pfizer Global Product Development.

“We are very pleased with the strong findings from TALAPRO-2, and although no definitive conclusions can be made across trials, the rPFS appears to be the longest observed in a randomized trial in this setting. These data highlight the potential for TALZENNA in combination with XTANDI, if approved, to become a new standard of care for mCRPC, irrespective of HRR gene mutation status. We look forward to discussing these data with global health authorities.”

“These exciting results from TALAPRO-2 underscore our long-standing commitment to men living with prostate cancer and delivering the next scientific breakthroughs,” said Suneet Varma, Global Oncology and U.S. President, Pfizer. “Based on these compelling combination data with XTANDI, we believe TALZENNA in prostate cancer may become the next potential blockbuster opportunity in our leading Pfizer Oncology portfolio, subject to regulatory approval.”