On August 27, 2025 Moleculin Biotech, Inc., (Nasdaq: MBRX) ("Moleculin" or the "Company"), a late-stage pharmaceutical company with a broad portfolio of drug candidates targeting hard-to-treat cancers and viral infections, reported the completion of its Phase 1B/2 (MB-106) clinical trial evaluating Annamycin in combination with Cytarabine (also known as "Ara-C" and for which the combination of Annamycin and Ara-C is referred to as AnnAraC) for the treatment of subjects with acute myeloid leukemia (AML) (Press release, Moleculin, AUG 27, 2025, View Source [SID1234655517]). Database lock for the trial is expected by the end of September, with the final clinical study report (CSR) projected to be published in early Q1 2026.
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In total, 22 subjects were enrolled in the trial, with all subjects (1L-7L) who received AnnAraC per protocol having completed their efficacy evaluations (n=20). The updated overall survival (OS) data reveal the following:
Median OS for Complete Remissions (CR): 15 months (n=8) with 4 subjects alive at study close
Median OS for the intent to treat (ITT) Population (1L-7L): 9 months (n=22; 13 subjects experienced an event, 9 subjects censored)
Median OS for 2L Efficacy Evaluable Population: 12 months (n=9)
"Industry publications1 note that the typical OS for relapsed AML patients is roughly 4-6 months, these results highlight a remarkable improvement, exceeding expectations by 30% or more," said Walter Klemp, Chairman and CEO of Moleculin Biotech.
As previously reported, 8 subjects in the ITT population of 22 (36%) achieved a complete remission (CR) following treatment with AnnAraC. Among the subjects treated in the second line (2L) setting (n=10), the CR rate (the same primary efficacy endpoint as in the ongoing Phase 2B/3 pivotal MIRACLE trial), was 50%. Median durability for the 8 subjects achieving a CR was 10 months and continuing at the end of the study. CR durability ranged from 2 months to 22 months. CRs were achieved in subjects with a variety of prior treatments, including traditional 7+3 and venetoclax regimens.
"We are glad to finally be in a position to close out our last Phase 2 AML trial, MB-106 by having completed follow-up on all subjects – some with durable CRs continuing – with database lock expected by the end of next month. While still technically preliminary, we are extremely pleased with the results of the MB-106 trial and look forward to the final CSR. These 2L data formed the basis for the design of the Phase 2B/3 pivotal MIRACLE trial with which we aim to gain eventual approval of Annamycin to serve the unmet need in 2L AML," added Walter Klemp, Chairman and CEO of Moleculin. "We continue to see meaningful, positive trends across all data points, particularly in overall survival and durability. Of note, an 80+ yr old subject who achieved a CR with one cycle of Annamycin and then received two maintenance cycles of Annamycin finally relapsed after 600+ days. He then received a fourth round of Annamycin under compassionate use and is now back in remission. These data are very exciting and continue to give us hope that Annamycin has the potential to address the significant unmet need for safe and effective therapies for R/R AML. We also need to reemphasize that we have not seen any cardiotoxicity in any of the subjects to date, a key aspect of Annamycin."
"We can now also report that 50% of subjects achieving CR moved on to a curative bone marrow transplant, which is the most sought-after goal of any induction therapy in AML," Mr. Klemp continued. "The results we have seen in 2L patients are better than any drug ever approved for second line AML and more than double the average for the last five drugs approved for 2L use."
"Looking ahead, we are focused on driving Part A of our Phase 3 MIRACLE trial forward and remain on track recruit the first 45 enrolled patients before the end of this year on which safety and efficacy will be unblinded. The final data from MB-106, coupled with the expected data from the MIRACLE trial will be invaluable as we continue to unlock the full potential of Annamycin for the treatment of AML," concluded Mr. Klemp.
The median age of subjects in MB-106 is 68 years. A total of 18 subjects had relapsed/refractory AML and 4 subjects were first line treatment. Two subjects discontinued early due to allergic reactions. All subjects who completed treatment had undergone post therapy disease response assessments (bone marrow assessment and/or peripheral blood evaluation) (Day 15 or later). No clinically significant signs of cardiotoxicity were noted during or after treatment in any of the subjects enrolled. The combination was well tolerated with myelosuppression and infections being the main adverse events (AEs). All data from MB-106 is preliminary and subject to change.
Annamycin, also known by its non-proprietary name of naxtarubicin, currently has Fast Track Status and Orphan Drug Designation from the FDA for the treatment of relapsed or refractory acute myeloid leukemia, in addition to Orphan Drug Designation for the treatment of soft tissue sarcoma. Furthermore, Annamycin has Orphan Drug Designation for the treatment of relapsed or refractory acute myeloid leukemia from the EMA.
The Company is currently evaluating Annamycin in combination with Cytarabine (also known as "Ara-C" and for which the combination of Annamycin and Ara-C is referred to as "AnnAraC") in a Phase 3 pivotal trial for the treatment of AML patients who are refractory to or relapsed after induction therapy (R/R AML). This global Phase 3 "MIRACLE" trial (derived from Moleculin R/R AML AnnAraC Clinical Evaluation) includes sites in the US, Europe and the Middle East. For more information about the MIRACLE trial, visit clinicaltrials.gov and reference identifier NCT06788756. Additionally, the clinical trial in the EU is on euclinicaltrials.eu and the reference identifier there is 2024-518359-47-00.