- The Food and Drug Administration has approved Pfizer’s Talzenna to treat some patients newly diagnosed with advanced prostate cancer, the company said Tuesday. Its clearance alongside another Pfizer drug called Xtandi broadens Talzenna’s use, although not as widely as the drugmaker had hoped.
- Talzenna’s approval only covers patients with a specific set of genetic alterations called “homologous recombination repair,” or HRR, mutations, where the drug regimen may be more effective. Pfizer aims to expand use to include all newly diagnosed patients if testing proves the combination helps patients live longer.
- The clearance is similar in scope to the recent approval of AstraZeneca and Merck & Co.’s rival drug Lynparza in the same setting. In that case, the FDA only authorized use in patients with a specific HRR mutation called BRCA, concluding that patients with those characteristics drove the benefits observed in testing.
The two drugs are from a class called PARP inhibitors that first showed their effectiveness in ovarian tumors, but have since been cleared for breast and pancreatic cancers as well. Until Tuesday, Talzenna had only been approved for breast cancer patients with BRCA mutations.
But PARP drugs have drawn concerns from U.S. regulators following findings that they don’t help certain patients and, in some cases, are associated with an increased risk of death. Multiple drugmakers have withdrawn PARP blockers in certain indications as a result.
Lynparza’s narrow clearance in first-line prostate cancer earlier this month reflected the ongoing “shift in the regulatory and clinical perception” of PARP drugs, SVB Securities analyst Andrew Berens recently wrote. Now Pfizer’s drug has gotten a similar clearance.
Pfizer appeared to be hoping for broader use. Data from the key study supporting Talzenna’s approval showed that a Talzenna-Xtandi regimen reduced the risk of progression in all patients who received it, regardless of HRR status, by 37%, when compared to Xtandi alone. The benefits were more pronounced among HRR patients, who had a risk reduction of 55%.
Patients haven’t been followed for long enough to detect whether Talzenna is meaningfully extending survival. A Pfizer spokesperson said in an email that if the drug is successful, the company will file for approval for in non-HRR patients as well.
Despite the FDA pushback, sales of PARP inhibitors are still increasing. While Pfizer doesn’t yet break out Talzenna sales — its first approval was in 2018 — AstraZeneca reported first quarter sales of $651 million for Lynparza, or 10% growth, while Merck reported its Lynparza alliance revenue grew 3% to $266 million in the first quarter.
SVB analyst Berens recently forecasted $680 million in peak U.S. sales for Lynparza in prostate cancer, though that projection is far lower than it once was.