AN2 Therapeutics, Inc. announced the company?s decision to voluntarily pause Phase 3 enrollment in the seamless Phase 2/3 clinical trial (EBO-301) evaluating epetraborole in treatment-refractory MAC lung disease, pending further data review. The double-blind, placebo-controlled trial has two arms comparing epetraborole plus optimized background regimen (OBR) versus placebo plus OBR. The voluntary pause was instituted following a blinded aggregate analysis of the ongoing Phase 2 study, including pooled patients from both treatment arms, which showed potentially lower than expected efficacy.

The decision was not due to safety concerns. The Phase 2 part of the trial is intended to inform the Phase 3 part of the trial. The company continues to expect to announce topline data from the Phase 2 part of the trial in summer 2024.

The company?s decision to pause enrollment enables time to further evaluate study data and for the independent Data Safety Monitoring Board (DSMB) to conduct an unblinded assessment and recommend next steps, which could include changes to the Phase 3 part of the study protocol. The Phase 2 part of the trial completed enrollment in September 2023 with 80 patients. The Phase 3 part of the trial has enrolled nearly 100 patients to date, a faster enrollment rate than previously anticipated.

Patients already enrolled in the Phase 2/3 trial will be allowed to continue on study. This double-blind, placebo-controlled superiority trial uses an adaptive design to evaluate the safety and efficacy of epetraborole in patients with treatment-refractory MAC lung disease. The Phase 2 part of the trial (n=80) assesses clinical response using various patient-reported outcome tools as well as the safety, efficacy and pharmacokinetics of epetraborole plus an OBR, when compared to a placebo plus an OBR.

The Phase 2 findings will be utilized to inform the clinical response measures evaluated in the Phase 3 part of the trial and confirm the final sample size. The primary objective in Phase 3 (n=at least 234) will be to determine if epetraborole plus an OBR, consisting of two or more standard-of-care drugs, is superior to placebo plus an OBR.