Moleculin Biotech Inc. reported that its lead drug candidate, Annamycin, showed no clinically significant cardiac toxicity in a pooled analysis of 90 relapsed/refractory acute myeloid leukemia patients, a finding that could overcome the primary safety barrier of conventional anthracyclines and address a key unmet need in heavily pretreated populations.
"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,” Walter Klemp, Chairman and Chief Executive Officer of Moleculin, said in a statement.
The analysis, conducted by a cardio-oncology laboratory at the Cleveland Clinic and detailed in an abstract for the European Hematology Association 2026 Congress, reviewed data from five completed trials. Among 78 patients with verifiable pre- and post-treatment ejection fraction data, zero developed clinically significant left ventricular dysfunction. The review also found that mean ejection fraction remained stable, with no link between higher cumulative doses and cardiac decline.
The findings are critical for Annamycin’s path forward in R/R AML, a market where patients have often been exposed to cardiotoxic first-line therapies like daunorubicin. By demonstrating a favorable safety profile, Moleculin (Nasdaq: MBRX) aims to position Annamycin as a viable option after venetoclax-based regimens have failed, a segment with limited effective treatments.
A Differentiated Approach to AML
Annamycin is a next-generation anthracycline, a class of potent chemotherapy agents widely used in treating leukemia. However, their use is often constrained by cumulative, dose-dependent cardiotoxicity. Moleculin designed Annamycin to avoid the multidrug resistance mechanisms that can limit efficacy while also engineering the molecule to be non-cardiotoxic. The EHA data, showing safety even at doses beyond conventional lifetime limits, provides strong clinical support for this intended design.
The company has initiated a pivotal Phase 3 adaptive-design study, the MIRACLE trial, to evaluate Annamycin in combination with cytarabine ("AnnAraC") for R/R AML. This follows a successful Phase 1B/2 study that gave the company confidence, with input from the FDA, to move into the late-stage trial. Beyond AML, Moleculin is also developing Annamycin for soft tissue sarcoma lung metastases and is advancing other pipeline candidates, including the immune modulator WP1066 for brain tumors and the antimetabolite WP1122.
While the cardiac safety data is a significant step, the company noted in its forward-looking statements that it will require significant additional financing to complete its clinical trials and that the findings are subject to long-term follow-up and further regulatory review.
This article is for informational purposes only and does not constitute investment advice.
