eFFECTOR Therapeutics Discloses Updated Data From Mid-Stage Breast Cancer Study

eFFECTOR Therapeutics Inc EFTR announced new interim data from dose escalation and Phase 2 expansion cohorts of a Phase 1/2 study of zotatifin in patients with estrogen receptor positive (ER+) metastatic breast cancer.

In the ZFA triplet cohort, patients received 0.07 mg/kg zotatifin combined with fulvestrant and abemaciclib.

The median progression-free survival was 7.4 months. As previously reported, 5/19 (26%) RECIST-evaluable patients had partial responses, including four confirmed and one unconfirmed. 

The ZFA triplet was generally well tolerated, with most zotatifin-related treatment-emergent adverse events (TEAEs) being Grade 1 or 2.

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. 

No dose-limiting toxicities or serious adverse events were observed in these nine patients; 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 stable disease in the 0.14 mg/kg cohort, and one stable disease in the 0.2 mg/kg cohort.

The dose escalation has been reopened in the ZFA triplet, with enrollment ongoing at 0.1 mg/kg zotatifin dosed once every two weeks, combined with fulvestrant and abemaciclib. 

The company expects to report additional data from dose escalation in the first half of 2024.

Price Action: EFTR shares are up 2.94% at $0.59 on the last check Friday.