Annamycin Plus Cytarabine Drive Potential OS Benefit in Acute Myeloid Leukemia

Treatment with the combination of annamycin and cytarabine (AnnAraC) generated a potential overall survival (OS) benefit in patients with acute myeloid leukemia (AML), according to final data from the phase 1/2 MB-106 trial (NCT06788756) announced by Moleculin Biotech.1

Findings showed that the median OS was 9 months in the intention-to-treat population (n = 22), which included patients receiving treatment as early as the first line and as late as the seventh line. Notably, patients who achieved a complete remission (CR; n = 8) experienced a median OS of 15 months, with 4 patients still alive at the end of the study. In patients treated in the second-line setting (n = 9), the median OS was 12 months.

“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 clinical study report,” Walter Klemp, chairman and chief executive officer of Moleculin Biotech, stated in a news release. “These second-line data formed the basis for the design of the phase 2B/3 pivotal MIRACLE trial [NCT05319587] with which we aim to gain eventual approval of Annamycin to serve the unmet need in second-line AML.”

Previously reported data from MB-106 showed that the ITT population experienced a CR rate of 36%, including a CR rate of 50% in the second line. The median duration of CR was 10 months (range, 2-22), and CRs were reported in patients who received a variety of prior therapies, including 7+3 chemotherapy and venetoclax (Venclexta)-based regimens.

“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,” Klemp added in the news release. “The results we have seen in second-line patients are better than any drug ever approved for second-line AML and more than double the average for the last 5 drugs approved for second-line use.”

MB-106 Overview

The multicenter, open-label, dose-escalation study enrolled patients at least 18 years of age with pathologically confirmed AML per WHO classification; patients could be treatment naive or have relapsed/refractory disease following induction therapy, defined as a bone marrow blasts percentage of more than 5%.2

For only the dose-expansion phase, patients were required to receive AnnAraC as first-, second-, or third-line therapy.

No chemotherapy, radiation, or major surgery was permitted within 2 weeks of the first study drug. Other key inclusion criteria comprised an ECOG performance status of 0 to 2, as well as adequate hematologic and organ function.

Patients with acute promyelocytic leukemia were excluded. Prior mediastinal radiotherapy and central nervous system involvement also precluded patients from enrollment.

All patients received liposomal Annamycin for 3 consecutive days, followed by 18 days off treatment during each 21-day cycle. Cytarabine was administered at 2.0 g/m2 per day for 5 consecutive days during cycle 1. The dose of cytarabine was consistent throughout all dose-escalation and -expansion cohorts.

Determining the maximum tolerated dose and the recommended phase 2 dose served as the trial’s primary end point. Secondary end points comprised pharmacokinetics and anti-leukemic activity.

“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,” Klemp stated in the news release.1 “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.”

References

1. Moleculin issues new positive AML overall survival data. News release. Moleculin Biotech. August 27, 2025. Accessed August 28, 2025. https://moleculin.com/moleculin-issues-new-positive-aml-overall-survival-data/
2. Study of liposomal annamycin in combination with cytarabine for the treatment of subjects with acute myeloid leukemia (AML). ClinicalTrials.gov. Updated December 20, 2024. Accessed August 28, 2025. https://www.clinicaltrials.gov/study/NCT05319587