Constellation Pharmaceuticals initiates Phase 2 portion of ProSTAR trial
Constellation Pharmaceuticals announced an update of the ProSTAR study, its ongoing Phase 1b/2 clinical trial of CPI-1205 in patients with metastatic castration-resistant prostate cancer. The ProSTAR study is evaluating CPI-1205, Constellation's potent and highly selective small-molecule EZH2 inhibitor, in combination with either enzalutamide or abiraterone / prednisone, in mCRPC patients who experienced disease progression while receiving the other ARS inhibitor. Based on encouraging results from the Phase 1b portion of ProSTAR, the Company has initiated dosing in the randomized Phase 2 portion studying CPI-1205 in combination with enzalutamide versus enzalutamide alone. Constellation has also decided to expand the Phase 2 portion of the study by adding an arm evaluating CPI-1205 in combination with abiraterone in the second-line setting. "We are pleased that CPI-1205 achieved its Phase 1b endpoints in ProSTAR, demonstrating an encouraging safety profile and evidence of clinical activity in both arms," said Adrian Senderowicz, Chief Medical Officer of Constellation Pharmaceuticals. "As we advance into the Phase 2 portion of the study, we believe combination therapy with CPI-1205 may provide a meaningful second-line treatment option to patients with metastatic castration-resistant prostate cancer, an area of significant unmet medical need. We are excited about expanding our opportunity to include an arm evaluating CPI-1205 in combination with abiraterone in the second-line setting, given that very few patients experience a 50% reduction in PSAs on second-line treatment with abiraterone and that time to progression in this setting is typically short."