Prelude Therapeutics reports results from Phase 1 trial of PRT3789

Prelude Therapeutics announced the first interim clinical data from its ongoing Phase 1 open-label, dose-escalation trial of PRT3789, a first-in-class SMARCA2 degrader, highly selective for SMARCA2 and designed to treat cancer patients with a SMARCA4 mutation. The data were presented at the European Society for Medical Oncology Congress 2024 in Barcelona, Spain. The study investigators reported that, as of the August 5, 2024 data cutoff date, 65 patients were safety evaluable, enrolled and treated. This included 46 efficacy evaluable patients with any tumor type harboring any SMARCA4 mutation. As reported by the study investigators, PRT3789 was generally well-tolerated through 8 dosing cohorts. Dose escalation continues, now in the 9th dosing cohort. The majority of adverse events reported by investigators have been mild to moderate. A maximum tolerated dose has not yet been identified. Overall, of the 26 advanced, heavily pre-treated NSCLC or esophageal patients evaluable for efficacy, 7 had tumor shrinkage. RECIST confirmed partial responses were observed in 3 patients. Additional patients demonstrated clinical benefit as measured by prolonged stable disease including one patient on treatment for more than 1 year.