eFFECTOR Therapeutics receives Fast Track Designation for zotatifin combination

eFFECTOR Therapeutics announced that the U.S. Food and Drug Administration has granted Fast Track designation for zotatifin in combination with fulvestrant and abemaciclib as second- or third-line therapy for the treatment of adult patients with estrogen receptor-positive/human epidermal growth factor-negative advanced or metastatic breast cancer with disease progression following treatment with endocrine therapy and a CDK 4/6 inhibitor. The Fast Track designation was granted following FDA review of preclinical and clinical data for zotatifin, including recent safety and efficacy data for the ZFA triplet. Zotatifin is being investigated in a Phase 1/2 dose escalation and expansion study, with cohorts currently enrolling in ER+/HER2- breast cancer. Data presented at the 2023 meeting of the American Society of Clinical Oncology showed that, in heavily pretreated patients, five out of 19 RECIST-evaluable patients achieved a partial response, including four confirmed and one unconfirmed. All five patients who achieved a PR had previously progressed on prior CDK 4/6 and fulvestrant treatments, and all five had received one or more prior lines of chemotherapy in the metastatic setting. Based on safety and tolerability results to date, dose escalation was resumed in combination with fulvestrant. Further updates to interim data from the ZFA triplet cohort and resumed dose escalation cohorts will be presented as a poster at SABCS on Friday, December 8, 2023.