FDA Greenlights Promontory Therapeutics' Phase 3 Trial Design for PT-112 in Metastatic Prostate Cancer
Key Insights
Promontory Therapeutics (search) has successfully completed an End of Phase 2 meeting with the FDA, reaching agreement on key aspects of a registrational Phase 3 trial for PT-112 in metastatic castration-resistant prostate cancer (search).
The FDA approved the proposed dosing regimen, patient population, study comparator, and endpoints, with an interim analysis provision that could allow for drug approval before study completion.
Preliminary clinical outcomes from the Phase 2 trial of PT-112 will be presented at the upcoming ASCO 2025 Annual Meeting on June 2nd, following recent presentation of immune response biomarker data at AACR 2025.
Promontory Therapeutics (search) announced today that it has successfully completed an in-person End of Phase 2 (EOP2) meeting with the U.S. Food and Drug Administration (FDA) regarding its lead candidate PT-112. The meeting outcome enables the company to advance toward a registrational Phase 3 study of PT-112 as a monotherapy for patients with metastatic castration-resistant prostate cancer (search) (mCRPC (search)).
The FDA agreed with Promontory's proposed dosing regimen for the Phase 3 trial, which aligns with the agency's Project Optimus initiative focused on dose optimization in oncology drug development. Agreement was also reached on the study design, endpoints, proposed comparator, and statistical framework for the pivotal trial.
Significantly, the FDA approved Promontory's proposal for an interim analysis, which could provide a pathway for drug approval prior to the full completion of the Phase 3 study. This approach could potentially accelerate patient access to the therapy if interim results demonstrate sufficient efficacy and safety.
Phase 2 Clinical Development Program
The recently completed Phase 2 study that formed the basis for the EOP2 meeting was a proof-of-concept and dose optimization trial conducted across sites in the United States and France. The study evaluated PT-112 monotherapy in patients with advanced mCRPC (search) and included three randomized dosing arms to determine the optimal therapeutic dose.
Immune response biomarker data from this trial were recently presented at the American Association of Cancer Research (AACR) 2025 Annual Meeting. The company has announced that preliminary clinical outcomes from the Phase 2 study will be presented on June 2nd at the upcoming American Society of Clinical Oncology (ASCO) 2025 Annual Meeting.
Next Steps in Regulatory Process
Following the successful FDA meeting, Promontory will prepare its full Phase 3 study submission for final regulatory review based on the FDA's guidance. The company also plans to conduct similar meetings with international regulatory authorities to align on global development strategy.
"This successful End of Phase 2 meeting represents a significant milestone in our development program for PT-112," said a company representative. "The FDA's agreement on our proposed Phase 3 trial design, including the potential for an accelerated approval pathway through interim analysis, validates our approach and brings us one step closer to potentially offering a new treatment option for patients with metastatic castration-resistant prostate cancer (search)."
About PT-112 and the Unmet Need in mCRPC
PT-112 is a small molecule with anti-cancer immune effects. Clinical data generated across six studies have demonstrated both single-agent and combination anti-cancer activity, along with what the company describes as "an attractive tolerability profile."
Metastatic castration-resistant prostate cancer (search) represents a significant unmet medical need. Despite advances in treatment options, mCRPC (search) remains a challenging disease with limited effective therapies once patients progress on standard treatments. Prostate cancer (search) is the second leading cause of cancer death in American men, with the metastatic castration-resistant form representing the most advanced stage of the disease.
Broader Development Program
Beyond prostate cancer (search), Promontory is also evaluating PT-112 in other indications. The company currently has an active Phase 2 trial underway at the National Cancer Institute under a Collaborative Research and Development Agreement. This study is assessing PT-112 monotherapy in thymic epithelial tumors (search), a rare disease with no FDA-approved treatments. Promontory holds FDA Orphan Drug designation for PT-112 in this indication.
Promontory Therapeutics (search) is a privately held, clinical-stage drug development company based in New York. The company focuses on developing small molecules with anti-cancer immune effects and has conducted research and development programs across the United States, Europe, and Asia. Recently, as part of its clinical expansion into France, Promontory was selected as the first international company member of the Paris-Saclay Cancer Cluster, Europe's emerging biotech hub for oncology.