HOUSTON — June 30, 2026

Moleculin Biotech, Inc. reported positive preliminary unblinded efficacy results from the first 45 patients enrolled in Part A of the pivotal Phase 2/3 MIRACLE trial evaluating Annamycin in combination with high-dose cytarabine (HiDAC) in patients with relapsed or refractory acute myeloid leukemia (R/R AML). On a full intent-to-treat basis with no patient exclusions, both Annamycin dose arms showed higher complete remission (CR) rates than the concurrent control arm. CR was 43% with 190 mg/m² Annamycin plus HiDAC and 36% with 230 mg/m², compared with 12% for the HiDAC control arm. Composite complete remission (CRc) rates were 50% and 57%, respectively, versus 29% for control. The Independent Data Monitoring Committee (iDMC) concluded that the efficacy trend supported continuation of the study.

MIRACLE Interim Analysis Shows Higher Remission Rates

The interim analysis evaluated 45 patients after a single treatment cycle, as specified by the MIRACLE protocol. The Annamycin treatment arms demonstrated higher CR and CRc rates than the randomized control arm, although the interim analysis did not reach formal statistical significance. The study population included a heavily pretreated R/R AML population, with 75.6% of patients older than 60 years, while 55.6% had previously received 7+3 therapy and 31.1% had received venetoclax-containing frontline regimens. Moleculin noted that historical studies such as MIRROS and CLASSIC I generally permitted multiple treatment cycles, making direct cross-trial comparisons inappropriate. The company therefore emphasized the concurrent randomized control arm as the most relevant comparison for the single-cycle interim analysis.

iDMC Supports Continued MIRACLE Trial Enrollment

The independent Data Monitoring Committee unanimously recommended continuing the MIRACLE trial, concluding that the experimental Annamycin arms demonstrated a strong numerical efficacy trend compared with placebo plus HiDAC. The committee did not recommend eliminating either Annamycin dose because the efficacy results between the two experimental arms remained sufficiently similar at this stage. Moleculin accepted the recommendation and will continue Part A as planned. The company reported that 67 of the targeted 90 patients have been enrolled in Part A, with the dose-selection portion intended to identify the optimal Annamycin dose before the selected arm advances into Part B of the pivotal study.

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Annamycin Advances Toward Pivotal AML Evaluation

MIRACLE is a randomized, double-blind, placebo-controlled, adaptive Phase 2/3 study evaluating L-Annamycin for injection in combination with cytarabine as second-line remission induction therapy for adults with R/R AML. Following Part A dose selection, efficacy data will be carried forward into the pivotal portion of the study, which is planned to evaluate an overall population of approximately 282 patients. The trial uses a prespecified group-sequential statistical design with an O’Brien-Fleming spending function, and the company stated that the interim analysis was not expected to establish statistical significance at this stage. Moleculin is developing Annamycin as an anthracycline designed to avoid multidrug resistance mechanisms and the cardiotoxicity associated with currently prescribed anthracyclines. The interim MIRACLE findings support continued clinical evaluation of Annamycin as Moleculin advances the program toward its planned pivotal analysis in R/R AML.

Source: Moleculin Biotech press release