Moleculin Biotech Inc. (NASDAQ: MBRX) announced that an independent review by Cleveland Clinic found no clinically significant cardiotoxicity with its experimental drug Annamycin in patients with relapsed or refractory acute myeloid leukemia.

The analysis examined cardiac safety data from 90 patients across five clinical trials who received doses beyond conventional anthracycline limits. Among 78 patients with verified pre- and post-treatment ejection fraction assessments, none met criteria for clinically significant left ventricular dysfunction, according to the company's statement.

The findings were published in an abstract at the European Hematology Association 2026 Congress. The cardio-oncology laboratory at Cleveland Clinic conducted the independent cardiac review, analyzing comprehensive cardiac monitoring data including ejection fraction measurements, ECGs, troponins, and strain assessments.

Mean ejection fraction remained stable throughout treatment, and researchers observed no association between cumulative dose and cardiac function decline. The study included heavily pretreated patients with substantial prior anthracycline exposure.

Annamycin is designed as a next-generation anthracycline that aims to avoid the cumulative cardiac toxicity associated with traditional anthracyclines while maintaining anti-cancer effectiveness. The drug is currently in late-stage development for treating relapsed or refractory acute myeloid leukemia.

"These data further strengthen the clinical rationale for Annamycin as a differentiated anthracycline with the potential to overcome one of the most significant barriers to treatment in AML," said Walter Klemp, Chairman and Chief Executive Officer of Moleculin.

The company is conducting the MIRACLE Trial, a pivotal Phase 3 study evaluating Annamycin in combination with cytarabine for relapsed or refractory acute myeloid leukemia treatment.