On September 28, 2026 Moleculin Biotech, Inc. (Nasdaq: MBRX) ("Moleculin" or the "Company") reported the publication of a peer-reviewed analysis of the cardiac safety of Annamycin (also known as L-Annamycin or naxtarubicin) in Frontiers in Cardiovascular Medicine. The publication, titled "Cardiac safety of L-Annamycin: a pooled analysis of five clinical trials," reports cardiac safety findings from 90 patients treated across five clinical trials in acute myeloid leukemia (AML) and metastatic soft tissue sarcoma (STS).

Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:

Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing

                  Schedule Your 30 min Free Demo!

The analysis was independently evaluated by a cardio-oncology laboratory at Cleveland Clinic and found no clinical or subclinical evidence of treatment-related cardiotoxicity, including at cumulative Annamycin exposures exceeding traditional lifetime limits for conventional anthracyclines.

"Publication of this comprehensive pooled analysis in a peer-reviewed cardiovascular medicine journal provides additional validation of the cardiac safety profile we have observed with Annamycin across our clinical development program," said Walter Klemp, Chairman and Chief Executive Officer of Moleculin. "For decades, the clinical utility of anthracyclines has been limited by cumulative cardiotoxicity and associated lifetime dose limits. The absence of detectable cardiac toxicity in patients receiving cumulative doses of Annamycin beyond those traditional thresholds supports our continued development of Annamycin and its potential to address an important limitation of the anthracycline class."

Pooled Analysis Evaluates Cardiac Safety Across Five Clinical Trials

The publication evaluated cardiac safety data from five sponsor- and investigator-initiated clinical trials, including three trials in AML and two trials in metastatic STS. Across the five studies, 90 patients received Annamycin, with paired echocardiographic data available for 78 patients.

Key findings from the pooled analysis include:

No significant change in cardiac function: Mean LVEF was 60.6% at baseline compared with 60.0% following treatment, with no statistically significant difference (p=0.84).
No relationship between cumulative dose and change in LVEF: The analysis found no association between cumulative Annamycin exposure and changes in LVEF.
No relationship between age and change in LVEF: Patient age was not associated with changes in LVEF.
No treatment-related cardiotoxicity identified: Serial ECGs, cardiac biomarkers including troponin I/T, and global longitudinal strain assessments showed no evidence of treatment-related cardiotoxicity.
High cumulative exposure: Patients received a median cumulative Annamycin dose of 660 mg/m², with findings observed despite cumulative exposures exceeding conventional anthracycline lifetime limits.
The authors concluded that Annamycin was not associated with clinical or subclinical evidence of cardiotoxicity at cumulative doses exceeding traditional anthracycline thresholds and that the findings support continued clinical evaluation of Annamycin as a potentially safer anthracycline platform.

Anthracyclines are among the most widely used and effective classes of cancer medicines, but their use can be limited by cumulative, dose-dependent cardiotoxicity. These cardiac risks can restrict treatment intensity, limit retreatment options and prevent some patients from receiving additional anthracycline therapy.

Annamycin is a fundamentally re-engineered anthracycline designed to maintain the antitumor activity of the anthracycline class while addressing the cardiotoxicity associated with conventional agents. Its liposomal formulation was developed to optimize tissue distribution and reduce cardiac exposure.

The newly published article builds upon previously presented clinical data demonstrating a lack of detectable cardiotoxicity with Annamycin despite cumulative exposure levels substantially exceeding conventional anthracycline limits. Moleculin previously reported that the pooled analysis included 90 patients across five completed clinical trials, with independent cardiac review conducted through the Cleveland Clinic Division of Cardiovascular Medicine.

Annamycin is currently being evaluated in Moleculin’s MIRACLE clinical development program for patients with relapsed or refractory AML.

(Press release, Moleculin, SEP 28, 2026, View Source [SID1234671113])