Pfizer's Phase III Prostate Cancer Success Supports Expanded Label for Talzenna-Xtandi Combo

Pfizer has announced encouraging results from a late-stage trial evaluating a combination of its PARP inhibitor Talzenna and ARPI drug Xtandi in patients with metastatic castration-resistant prostate cancer (mCRPC). The Phase III TALAPRO-2 study indicated that the combination treatment significantly improved overall survival (OS) compared to Xtandi alone.

According to the topline analysis, the combination of Talzenna and Xtandi demonstrated a "statistically significant and clinically meaningful improvement" in OS. This OS benefit was observed not just in patients with mutations in the homologous recombination repair (HRR) gene but in all patients irrespective of their biomarker status.

This positive outcome follows earlier findings from February 2023, where the TALAPRO-2 study showed that the combination therapy resulted in a 37% reduction in the risk of disease progression or death. The final analysis of the study maintained this benefit in terms of radiographic progression-free survival, with the results being deemed "clinically meaningful" by Pfizer.

Regarding safety, the adverse events reported in the TALAPRO-2 trial were consistent with the previously known toxicity profiles of Talzenna and Xtandi when used individually.

Roger Dansey, Pfizer’s chief development officer for oncology, highlighted the significance of these findings, noting that Talzenna plus Xtandi is now the first and only PARP inhibitor combined with an ARPI to show a significant improvement in survival for mCRPC patients, regardless of their mutation status. Pfizer intends to present the complete data and analysis of the TALAPRO-2 study at an upcoming medical conference.

Additionally, Pfizer plans to submit these findings to global health authorities to seek an update and potential expansion of the approved label for Talzenna. As of June 2023, the FDA had approved the combination of Talzenna and Xtandi for mCRPC patients specifically with HRR gene mutations. The combination therapy works by combining Talzenna’s ability to block the PARP protein, which aids in DNA repair, with Xtandi’s mechanism of inhibiting the androgen receptor, thereby limiting cell proliferation and inducing cell death.

In other related news, former Pfizer executives Ian Read and Frank D’Amelio have expressed their support for the current leadership of the company. In a statement, they voiced their confidence in Pfizer Chairman & CEO Albert Bourla and the senior management team, asserting their belief in the leadership's ability to deliver shareholder value over time.

Meanwhile, The Wall Street Journal reported on an activist investor, Starboard Value, acquiring a $1 billion stake in Pfizer. The investor is reportedly planning to initiate a campaign to revitalize the company, which could potentially involve removing CEO Albert Bourla. However, Read and D’Amelio have refuted claims that they are interested in collaborating with Starboard in this effort.