eFfector announces interim data from Phase 2 expansion cohorts of zotatifin

eFFECTOR Therapeutics announced new positive interim data from dose escalation and Phase 2 expansion cohorts of a Phase 1/2 clinical study of zotatifin in patients with estrogen receptor positive metastatic breast cancer. The data, reflecting a cutoff date of Nov. 17, 2023, is being presented by Ezra Rosen, M.D., Ph.D., Medical Oncologist and Early Drug Development Specialist, Memorial Sloan Kettering Cancer Center, at the 2023 San Antonio Breast Cancer Symposium, held from December 5 – 9, 2023 in San Antonio, Texas. In the ZFA triplet cohort, wherein patients with a median of four prior lines of therapy for metastatic disease received 0.07 mg/kg zotatifin dosed on Days 1 and 8 of 21-day cycles, combined with fulvestrant and abemaciclib, the mPFS was 7.4 months. As previously reported, five of 19 RECIST-evaluable patients had partial responses, including four confirmed and one unconfirmed. The ZFA triplet was generally well tolerated, with the large majority of zotatifin-related treatment-emergent adverse events being Grade 1 or 2. The most common zotatifin-related TEAEs were nausea, vomiting and fatigue, all Grade 1 or 2. The most common Grade 3 or higher zotatifin-related TEAEs were anemia and blood creatinine phosphokinase increase, each in two of 20 patients. Four of 20 of patients discontinued treatment due to adverse events of any cause. In the new ZF dose escalation cohorts, three patients were enrolled at each dose level of 0.1, 0.14 and 0.2 mg/kg zotatifin administered once every two weeks, combined with fulvestrant. The patients were heavily pretreated, with a median of four prior lines of treatment for metastatic disease. There were no dose-limiting toxicities or serious adverse events observed in these nine patients and enrollment is ongoing now at 0.28 mg/kg zotatifin combined with fulvestrant. There was one confirmed partial response in the 0.1 mg/kg cohort, two instances of stable disease in the 0.14 mg/kg cohort and one instance of stable disease in the 0.2 mg/kg cohort.