Moleculin Biotech announced positive interim efficacy data from its ongoing European Phase 1B/2 clinical trial evaluating Annamycin for acute myeloid leukemia (AML) treatment, presenting findings to key opinion leaders at the 65th American Society of Hematology Meeting in San Diego. The next-generation anthracycline demonstrated a complete response rate of 36% in intent-to-treat subjects with sustained durability and maintained its cardiotoxicity-free profile across all treated patients.
Clinical Efficacy Results
The MB-106 trial showed promising efficacy signals with 4 complete responses among 11 evaluable intent-to-treat subjects, representing a 36% complete response rate. Among the 9 subjects who received Annamycin dosing, the complete response rate reached 44%. The responses demonstrated notable durability, with complete remissions lasting up to 8 months and continuing to climb, with no relapses observed to date in the trial.
"We believe that our growing body of preliminary clinical data demonstrated by Annamycin in the treatment of patients with AML continues to be highly encouraging and bolsters our confidence in its potential to be a meaningful option for patients," commented Walter Klemp, Chairman and Chief Executive Officer of Moleculin. "While still preliminary, the complete response rate we are seeing continues to reflect what we believe is an efficacy level greater than we need for eventual approval of Annamycin."
The trial enrolled patients with a median age of 69 years and a median number of prior therapies for AML of one. Two of the complete responders are too recent to measure durability, while the company continues to monitor response duration in ongoing patients.
Safety Profile and Cardiotoxicity Absence
Annamycin maintained its differentiated safety profile with zero evidence of cardiotoxicity across all measurements including ejection fraction, strain analyses, ECGs, and cardiac biomarkers including Troponin-I and T. This cardiotoxicity-free profile extends across 66 subjects treated in multiple Annamycin clinical trials, including 50 subjects treated over the lifetime maximum anthracycline dose set by the FDA.
The trial experienced two subject withdrawals due to adverse events: one allergic reaction to Annamycin (the first observed across over 70 subjects dosed in multiple trials) and one allergic reaction to cytarabine. Additionally, one subject experienced a grade 4 serious adverse event with septic shock caused by E. coli, which was reported to regulatory bodies and ethics committees as ongoing while the subject recovers.
Trial Progress and Regulatory Status
The MB-106 Phase 1B/2 clinical trial has recruited 16 subjects to date, representing 59% of target enrollment. The company expects to achieve full recruitment within the next few months, with recruitment rates exceeding expectations. Nine clinical sites across Poland and Italy have been activated, with plans for up to eleven total sites in the European Union.
Annamycin currently holds Fast Track Status and Orphan Drug Designation from the U.S. Food and Drug Administration for treating relapsed or refractory acute myeloid leukemia, in addition to Orphan Drug Designation for soft tissue sarcoma treatment.
Drug Mechanism and Development Strategy
Annamycin represents a next-generation anthracycline designed to accumulate in lungs at up to 30-fold the level of doxorubicin in animal models while avoiding multidrug resistance mechanisms that limit current anthracycline efficacy. The absence of cardiotoxicity potentially removes the usage limitations imposed on doxorubicin and other currently approved anthracyclines.
"Having 38% of subjects with a median age of 68 in our MB-106 AML study receiving a full course of Annamycin show a complete response with durability of up to approximately 8 months and counting, we believe, is exceptional while also demonstrating no cardiotoxicity," stated Dr. Paul Waymack, Senior Chief Medical Officer.
The company is simultaneously developing Annamycin for soft tissue sarcoma lung metastases, where preliminary data showed median overall survival of 11 months in heavily pre-treated subjects and progression-free survival of 3.4 months for subjects with fewer prior therapies dosed at or below 330 mg/m2.
