The overall survival data from the late-stage trial will help Pfizer in its bid to expand the label for Talzenna and Xtandi, potentially covering all patients with metastatic castration-resistant prostate cancer regardless of biomarker status.
Pfizer on Thursday announced that a combination regimen of its PARP inhibitor Talzenna and ARPI drug Xtandi improved survival in patients with metastatic castration-resistant prostate cancer, according to a topline analysis of the Phase III TALAPRO-2 study.
Specific data in the announcement were sparse, with Pfizer revealing only that Talzenna plus Xtandi led to a “statistically significant and clinically meaningful improvement” in overall survival (OS) versus Xtandi alone. The OS benefit was significant not only in the subgroup of participants harboring mutations in the homologous recombination repair (HRR) gene but in all-comers regardless of their biomarker status.
Thursday’s readout follows a previous data drop from TALAPRO-2 in February 2023, which found that the combo treatment induced a 37% reduction in the risk of disease progression or death. At the time of the final analysis, this benefit in radiographic progression-free survival remained “clinically meaningful,” according to Pfizer.
In terms of safety, the adverse events in TALAPRO-2 were consistent with the known toxicity profiles of the individual medicines.
With these findings, Talzenna plus Xtandi becomes the “first and only PARP inhibitor in combination with an ARPI to significantly improve survival” in metastatic castration-resistant prostate cancer (mCRPC) patients, “regardless of mutation status,” Roger Dansey, Pfizer’s chief development officer for oncology, said in a statement. The pharma plans to present complete data and analysis for TALAPRO-2 at an upcoming medical meeting.
Pfizer will also share these findings with global health authorities “to update and potentially expand the approved label for Talzenna.”
In June 2023, the FDA approved Talzenna plus Xtandi for mCRPC, but specifically for patients with HRR gene mutations. The combination regimen brings together Talzenna’s action of blocking the PARP protein, which helps cells repair DNA damage, with Xtandi’s mechanism of inhibiting the androgen receptor to limit cell proliferation and trigger cell death.
In related news, Pfizer’s ex-CEO Ian Read and ex-CFO Frank D’Amelio reaffirmed their support for the pharma’s current leadership. In a statement late Wednesday, the former executives said that they are “fully supportive of Pfizer Chairman & CEO Albert Bourla” and of the pharma’s senior management and board of directors. “We are confident that over time they will deliver shareholder value,” they said.
On Sunday, The Wall Street Journal reported that activist investor Starboard Value snapped up a $1 billion stake in Pfizer and was preparing to launch a campaign to turn the business around, a move that reportedly would include removing Bourla from his post. At the time, anonymous insider sources said that Read and D’Amelio expressed interest in helping Starboard—a claim they refute.
