Moleculin Biotech Inc. (NASDAQ: MBRX) enrolled its 45th patient in the MIRACLE Phase 2B/3 trial evaluating Annamycin combined with cytarabine for treating relapsed or refractory acute myeloid leukemia, the company announced March 23.

The enrollment milestone triggers preparation for an interim data unblinding expected in mid-2026. The unblinding will include approximately 30 patients treated with the drug combination at two dose levels and 15 patients in a control group receiving cytarabine plus placebo.

The company reported preliminary blinded results from the first 30 patients showed a 40% composite complete remission rate, consisting of 30% complete remission and 10% complete remission with partial hematologic recovery. About 35% of subjects had previously failed venetoclax-based therapies.

"We believe this upcoming data readout represents the most important milestone in our history to date," said Walter Klemp, chairman and CEO of Moleculin. "Our Phase 2 AML MB-106 clinical trial generated greater efficacy than any drug ever approved for relapsed or refractory AML."

The MIRACLE trial operates across eight countries using an adaptive design intended to integrate Phase 2B data into the planned Phase 3 portion. Following the 45-patient interim readout, enrollment will continue toward 90 patients for a second unblinding expected in the third quarter of 2026.

The trial protocol allows for a streamlined registration pathway and potential accelerated approval based on complete remission as the primary endpoint. More than 100 patients have been treated with Annamycin to date without associated cardiotoxicity, according to the company.

Moleculin is developing Annamycin as a next-generation anthracycline designed to avoid multidrug resistance and cardiotoxicity associated with current anthracyclines. The company also has ongoing programs targeting pancreatic cancer, brain tumors and soft tissue sarcoma.