Clinical Activity of MRT-2359 + Enzalutamide Combo in Heavily Pretreated Metastatic CRPC Patients with Androgen Receptor Mutations Announced

“We continue to be highly encouraged by the clinical activity observed with MRT-2359 in combination with enzalutamide in heavily pretreated mCRPC patients, a population with limited therapeutic options, with an overall disease control rate (DCR) of 64%. The responses seen in the subset of patients harboring AR mutations were particularly compelling, with 4 of 4 patients demonstrating a PSA response, including 2 PSA90 responses and 2 PSA50 responses. Two of the 4 patients with AR mutations showed a RECIST response, and the DCR in the AR mutant population was 100%. We believe these results are especially promising given that most of the patients with AR mutations, even more so than in the overall mCRPC trial population, received prior chemotherapy as well as radioligand therapy, or even experimental bispecific antibodies,” said Markus Warmuth, M.D., Chief Executive Officer of Monte Rosa Therapeutics. “We were also pleased to see through our biomarker work that MRT-2359 significantly impacted both the MYC and the E2F signaling pathways, suggesting a mechanism of action that is at least in part independent of inhibiting AR signaling, and confirming our preclinical studies. Given these findings and the favorable safety profile observed to date, we believe there is a significant opportunity for MRT-2359 in the rapidly evolving treatment landscape of prostate cancer.”