Pfizer's Prostate Cancer Combo Shows Promise, Inks New Antibody Discovery Deal

In a significant development for prostate cancer treatment, Pfizer has unveiled promising phase 1 data for its investigational EZH2 inhibitor, mevrometostat, in combination with Xtandi (enzalutamide). The pharmaceutical giant has also announced a new collaboration with Alloy Therapeutics to enhance its antibody discovery capabilities.

Mevrometostat-Xtandi Combo Demonstrates Efficacy in Prostate Cancer Trial

Pfizer's phase 1 trial results, initially scheduled for presentation at the ASCO Genitourinary Cancers Symposium, reveal that the combination of mevrometostat and Xtandi reduced prostate cancer progression by 49% compared to Xtandi alone in patients with metastatic castration-resistant prostate cancer (mCRPC).

The open-label trial, which enrolled 81 previously treated mCRPC patients, showed a median radiographic progression-free survival of 14.3 months for the 41 patients receiving the combination therapy, compared to 6.2 months for the 40 patients on Xtandi monotherapy.

For patients with measurable disease at baseline, the overall response rate was 26.7% in the combination arm, versus 14.3% in the Xtandi-only group.

While the combination therapy demonstrated improved outcomes, it also showed a higher rate of grade 3 or higher treatment-emergent adverse events (TEAEs) at 53.7%, compared to 42.5% in the monotherapy cohort. The most common severe TEAEs in the combination arm were diarrhea, neutropenia, and sepsis. Importantly, no treatment-related deaths were reported as of September 2024.

Based on these encouraging results, Pfizer has initiated two phase 3 trials to further evaluate the mevrometostat-enzalutamide combination in different mCRPC patient populations.

Pfizer Expands Antibody Discovery Capabilities with Alloy Therapeutics Partnership

In a separate announcement, Pfizer has entered into a new agreement with Boston-based Alloy Therapeutics to develop a platform for discovering antibodies against challenging targets. This collaboration builds upon an existing partnership between the two companies.

Under the terms of the deal, Alloy will receive an undisclosed upfront payment and is eligible for potential milestone payments. The partnership will leverage Alloy's ATX-Gx platform, which utilizes fully humanized transgenic mice and is currently employed by over 170 partners in the industry.

The expanded collaboration aims to combine Pfizer's expertise with Alloy's innovative technologies, including the ATX-CLC platform, which generates human antibodies using a single light chain sequence. This strategic partnership is expected to enhance Pfizer's capabilities in addressing difficult-to-target proteins and expand its antibody discovery efforts.