-Pfizer Inc. announced positive topline results from the Phase 3 TALAPRO-3 study of TALZENNA^® (talazoparib), an oral poly ADP-ribose polymerase (PARP) inhibitor, in combination with XTANDI^® (enzalutamide), an androgen receptor pathway inhibitor (ARPI), in people with homologous recombination repair (HRR) gene-mutated metastatic castration-sensitive prostate cancer (mCSPC), also known as metastatic hormone-sensitive prostate cancer (mHSPC).

The study met its primary endpoint, with TALZENNA plus XTANDI demonstrating a statistically significant and clinically meaningful improvement in radiographic progression-free survival (rPFS), compared to placebo plus XTANDI. The results markedly exceeded the pre-specified target hazard ratio of 0.63, with the majority of patients remaining progression-free at the time of analysis. Consistent efficacy benefit was also observed in patients whose tumors harbored BRCA and non-BRCA HRR gene alterations.

“Current treatment approaches leave many patients with HRR gene-mutated metastatic castration-sensitive prostate cancer vulnerable to early disease progression,” said Neeraj Agarwal, M.D., FASCO, Professor and Presidential Endowed Chair of Cancer Research at Huntsman Cancer Institute at the University of Utah, and global lead investigator for TALAPRO-3. “The TALAPRO-3 results demonstrate that treatment with TALZENNA in combination with XTANDI earlier in the disease course significantly extends the time patients can live without their cancer worsening.”

At the time of the interim analysis, results showed a strong trend toward improved overall survival (OS), a key secondary endpoint. Benefits were also observed in other secondary endpoints, including overall response rate, duration of response, and time to Prostate-Specific Antigen (PSA) progression. The safety of TALZENNA plus XTANDI was consistent with the known safety profile of each medicine, and no new safety signals were identified.

Prostate cancer is the second most common cancer in men worldwide, with an estimated 1.4 million new cases diagnosed globally in 2022¹ and 330,000 new cases anticipated in the United States in 2026.² mCSPC, is a form of advanced prostate cancer that has spread beyond the prostate but is still sensitive to androgen inhibition.³ Despite recent treatment advances, 50% to 65% of patients with mCSPC progress to metastatic castration-resistant prostate cancer (mCRPC) within two years, with increased risk in HRR gene-mutated patients.^4-6

“Alterations in DNA damage repair genes, such as HRR genes, are found in approximately 25% of metastatic prostate cancers and associated with a worse prognosis and are less responsive to current standards of care, representing a group with a high unmet need,” said Jeff Legos, Chief Oncology Officer, Pfizer. “TALZENNA plus XTANDI is already a standard of care in HRR gene-mutated metastatic castration-resistant prostate cancer, and these unprecedented results demonstrate the potential to deliver benefit earlier in the disease course. These findings underscore Pfizer’s leadership in precision medicine and commitment to bringing more personalized treatment options to people living with prostate cancer.”

TALZENNA plus XTANDI in HRR gene-mutated mCSPC is an investigational treatment regimen. The TALAPRO-3 results will be submitted for presentation at an upcoming medical congress and will be discussed with global health authorities for potential regulatory submissions.

TALZENNA plus XTANDI is currently approved in 60 countries, including in the United States for adults with HRR gene-mutated mCRPC and in the European Union for adults with mCRPC in whom chemotherapy is not clinically indicated.