Monte Rosa And Johnson & Johnson Partner To Advance MRT-2359 Combination In Prostate Cancer Phase II Study

Monte Rosa Therapeutics, Inc. announced it has entered into a supply agreement with Johnson & Johnson to evaluate its investigational therapy MRT-2359 in combination with ERLEADA (apalutamide) for patients with metastatic castration-resistant prostate cancer (mCRPC) harboring androgen receptor (AR) mutations. The combination will be studied in a planned Phase II clinical trial expected to begin in the third quarter of 2026. MRT-2359 is an orally available molecular glue degrader targeting GSPT1, developed by Monte Rosa as part of its next-generation protein degradation platform. 

ERLEADA, an androgen receptor inhibitor developed by Janssen Research & Development, is already approved for treating metastatic castration-sensitive prostate cancer and non-metastatic castration-resistant prostate cancer. Under the terms of the agreement, Monte Rosa will sponsor and conduct the clinical study, while Johnson & Johnson will supply ERLEADA for use in the trial. The Phase II study is expected to enroll up to 25 patients and is designed to evaluate the safety and efficacy of the combination therapy in individuals with AR-mutated mCRPC.

“We are pleased to enter into this supply agreement with Johnson & Johnson to further explore the potential of MRT-2359 in combination with next-generation AR inhibitors such as apalutamide in patients with advanced prostate cancer,” said Markus Warmuth, M.D., Chief Executive Officer of Monte Rosa Therapeutics. “Based on the compelling clinical activity observed to date in heavily pretreated patients with AR mutations, we believe this combination approach holds significant promise. Data generated from these studies have the potential to further confirm MRT-2359’s clinical activity and may position the program for advancement into registrational studies, representing an important step forward for prostate cancer patients with limited therapeutic options for this respective patient population.”

The trial will assess key endpoints including prostate-specific antigen (PSA) response, tumor response based on RECIST criteria, duration of response, progression-free survival (PFS), radiographic PFS, and overall safety. If promising activity is observed, the study may be expanded to include additional patient populations, such as those who have not previously received next-generation AR inhibitors. This collaboration builds on earlier encouraging results from Monte Rosa’s ongoing Phase I/II trial, where MRT-2359 demonstrated positive outcomes in combination with enzalutamide in heavily pretreated mCRPC patients.