Phase 3 data showed that the combination resulted in a 37% reduction in risk of disease progression or death in men with advanced prostate cancer.
The FDA has granted priority review to the supplemental new drug application for the combination of Talzenna (talazoparib) and Xtandi (enzalutamide) to treat patients with metastatic castration-resistant prostate cancer (mCRPC). Priority review generally is six months compared with 10 months for standard review.
Metastatic castration-resistant prostate cancer is a cancer that has spread beyond the prostate gland and has progressed despite medical or surgical treatment to lower testosterone. About 10% to 20% of prostate cancer patients develop mCRPC within five to seven years of diagnosis.
Both therapies were developed by Pfizer. Talzenna is an oral PARP inhibitor, which plays a role in DNA damage repair, and is indicated to treat patients with BRCA-mutated, HER2- advanced breast cancer. Xtandi is androgen receptor inhibitor indicated to treat patients with castration-resistant prostate cancer and metastatic castration-sensitive prostate cancer.
Data from the phase 3 TALAPRO-2 study show the combination resulted in a 37% reduction in risk of disease progression or death in men with advanced prostate cancer. A trend in overall survival (OS) favoring the combination was also observed, but these data are immature, the company said. The final overall survival will be reported once the predefined number of survival events has been reached.
“In addition to delaying disease progression, this combination delayed prostate-specific antigen progression and time to chemotherapy without adversely impacting patient quality of life,” Neeraj Agarwal, M.D., professor of oncology and Presidential Endowed Chair of Cancer Research at Huntsman Cancer Institute, University of Utah, and lead investigator for TALAPRO-2, said in a press release. “The TALAPRO-2 results support the potential for this combination to be practice-changing, with strong, highly consistent efficacy and observations in mCRPC patients both with or without HRR gene mutations, and across clinically relevant sub-populations.”
The study also showed clinically meaningful improvement in median radiographic progression-free survival (rPFS) for patients in the study treated with Talzenna/Xtandi combination across several prospectively assessed subgroups including homologous recombination repair (HRR)-deficient and homologous recombination repair-non-deficient or unknown. Median time to clinical deterioration in global health status/quality of life was also longer in those treated with the two therapies — 30.8 vs 25.0 months for placebo.
The most common grade ≥3 treatment emergent adverse events (TEAEs) were anemia, low neutrophil, and low platelet counts. TEAEs led to discontinuation of Talezenna in 19.1% of patients versus 12.2% of placebo. Discontinuation rates of Xtandi were generally consistent across both study arms (10.8% vs 11.0%).