Pfizer’s Phase 3 TALAPRO‑3 trial shows TALZENNA® plus XTANDI® cut progression risk by 52% in HRR‑mutated metastatic castration‑sensitive prostate cancer, reinforcing biomarker‑driven strategies and supporting regulatory expansion.
Written By: Mahathi Palivela, PharmD
Reviewed By: Pharmacally Editorial Team
Pfizer reported positive Phase 3 results from the pivotal TALAPRO-3 study (NCT04821622), showing that TALZENNA® (talazoparib) combined with XTANDI® (enzalutamide) reduced the risk of radiographic progression or death by 52% compared with XTANDI alone in men with homologous recombination repair (HRR) gene-mutated metastatic castration-sensitive prostate cancer (mCSPC).
Findings were presented at the 2026 ASCO Annual Meeting and published simultaneously in The New England Journal of Medicine.
After a median follow-up exceeding 37 months, the combination achieved a hazard ratio of 0.48 (95% CI: 0.36–0.65; p<0.0001). Median radiographic progression-free survival (rPFS) was not reached in the TALZENNA arm, compared with 46 months in patients receiving placebo plus XTANDI. Kaplan-Meier estimates showed three-year rPFS rates of 77% and 56%, respectively.
Genetic Subgroup Consistency
Clinical benefit remained consistent across predefined HRR subgroups. In patients with BRCA alterations, the regimen reduced the risk of progression or death by 63% (HR 0.37), with three-year rPFS rates of 77% versus 49%. Among patients with non-BRCA HRR alterations, the combination reduced risk by 43% (HR 0.57), with corresponding three-year rPFS rates of 76% and 60%.
HRR gene alterations are present in roughly one-third of patients with mCSPC and are associated with more aggressive disease and poorer clinical outcomes, highlighting the importance of biomarker-driven treatment strategies in earlier-stage metastatic disease.
Overall Survival and Secondary Endpoints
Interim overall survival data favored the combination (HR 0.77; p=0.09), although the analysis did not reach statistical significance at the time of data cutoff. Median overall survival remains unreached in both treatment arms.
The regimen also delayed prostate-specific antigen (PSA) progression and postponed the need for subsequent anticancer therapy, supporting durable disease control beyond the primary endpoint.
Safety Profile
The safety profile was consistent with previous TALZENNA studies. The most common treatment-emergent adverse events were anemia, fatigue, decreased neutrophil count, and asthenia.
Grade 3 or higher anemia occurred in 51% of patients receiving TALZENNA plus XTANDI compared with 3% in the control arm. Despite the higher incidence, discontinuation due to anemia was limited to 5%, with most events managed through dose modifications and supportive care.
Clinical and Regulatory Outlook
Lead investigator Dr. Neeraj Agarwal highlighted the durable disease control observed across both BRCA and non-BRCA HRR-mutated populations, reinforcing the potential value of introducing PARP inhibitor-based therapy earlier in the treatment journey.
The findings also strengthen the case for early genetic testing to identify patients who may benefit from targeted treatment before progression to metastatic castration-resistant prostate cancer.
TALZENNA plus XTANDI is currently approved in more than 60 countries for HRR-mutated metastatic castration-resistant prostate cancer. Pfizer is engaging with global regulatory authorities to support expansion into the metastatic castration-sensitive setting, while ongoing follow-up from TALAPRO-3 will provide final overall survival data that could inform future regulatory decisions.
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About the Writer
Mahathi Palivela (LinkedIn) is pursuing PharmD and has a strong interest in Clinical Pharmacy and Patient safety. She is passionate about handling and analyzing patient data, and translating clinical insights into clear, meaningful summaries. She aims to apply this interest in Medical Writing and Pharmacovigilance, focusing on improving patient outcomes through careful data interpretation and communication.