Monte Rosa Therapeutics provides development progress on ongoing MRT-2359 study

Monte Rosa Therapeutics (GLUE) reported an update from its ongoing Phase 1/2 open-label, multicenter study of MRT-2359 in patients with MYC-driven solid tumors. MRT-2359 is an investigational, orally bioavailable, GSPT1-directed MGD discovered and developed by Monte Rosa Therapeutics. Enrollment Highlights: Patients have been dosed with MRT-2359 in 6 dose levels across two dosing schedules. Safety Highlights: Using the 5/9 dosing schedule, doses of 0.5 mg and 1 mg per day were identified as having a generally favorable safety profile, while doses of 1.5 mg or higher were above the maximum tolerated dose with thrombocytopenia being a dose limiting toxicity. Using the 21/7 schedule, both 0.5 and 0.75 mg were identified as having a generally favorable safety profile. 0.5 mg using the 21/7 dose schedule was selected as the recommended phase 2 dose for any expansion cohorts of the Phase 1/2 study. Pharmacodynamic Highlights: Pharmacodynamic effects were assessed utilizing mass spectrometry measurements of GSPT1 protein levels from paired tumor biopsies. The target levels of approximately 60% GSPT1 degradation were observed in tumor biopsies across all dose levels in relevant tumor types.