Moleculin Biotech, Inc., a clinical-stage pharmaceutical company developing therapies for difficult-to-treat cancers and viral diseases, has announced updated preliminary blinded results from Part A of its pivotal Phase 2/3 MIRACLE trial (MB-108) evaluating Annamycin in combination with cytarabine (AnnAraC) for patients with relapsed or refractory acute myeloid leukaemia (R/R AML).

Based on data from 62 evaluable patients, the study reported a 24 percent complete remission rate and a 37 percent composite complete remission (CRc) rate. Nearly half of the evaluable patients (48 percent) had previously received venetoclax-based therapy, a population typically associated with poor treatment outcomes. Within this subgroup, Annamycin achieved a 23 percent CR rate and a 37 percent CRc rate, mirroring the response observed across the overall study population.

According to the company, these findings suggest that previous treatment failure with venetoclax does not appear to diminish the therapeutic activity observed with the investigational regimen.

Commenting on the interim findings, Walter Klemp, Chairman and Chief Executive Officer of Moleculin Biotech, said the results are particularly encouraging given the increasing proportion of difficult-to-treat patients enrolled in the trial.

"Nearly half of the evaluable patients entered the study after failing prior venetoclax therapy, a group for whom published salvage remission rates remain extremely low and median survival is measured in only a few months. Despite this, the blinded composite remission rate has remained consistent with that seen in the broader study population, providing additional confidence as we approach completion of Part A," he said.

Klemp also noted that the company continues to observe no evidence of cardiotoxicity, one of the key characteristics that differentiates Annamycin from conventional anthracycline chemotherapy agents.

Because the latest analysis remains blinded, it includes patients from both the investigational and placebo-controlled treatment arms. Consequently, the remission rates are expected to be lower than those reported in the June 2026 interim unblinded analysis, where the two Annamycin treatment arms achieved composite complete remission rates of 50 percent and 57 percent, compared with 29 percent in the control arm. The company emphasized that the two analyses are not directly comparable.

Across three successive blinded analyses conducted after 30, 45 and 62 evaluable patients, the composite complete remission rate has remained stable between 37 and 40 percent, despite the growing proportion of patients previously treated with venetoclax.

The MIRACLE trial has now enrolled 74 of the planned 90 patients for Part A, with completion of enrollment expected in September 2026. Comprehensive unblinded efficacy and safety data are anticipated between December 2026 and February 2027.

The global, multicentre Phase 2/3 MIRACLE trial is evaluating two dose levels of Annamycin in combination with cytarabine against cytarabine plus placebo in adults with relapsed or refractory AML following a single prior induction therapy. The study uses an adaptive design, with data from Part A and Part B expected to be combined for the primary efficacy analysis.

Moleculin believes the upcoming data release could represent an important milestone for the development programme.

"As enrollment nears completion, Moleculin is entering what we believe will be a major value-inflection period. The comprehensive Part A results have the potential to validate Annamycin's differentiated clinical profile, support progression into Part B, strengthen our regulatory strategy and expand partnership opportunities," Klemp said.

The company highlighted the unmet medical need among patients who relapse after venetoclax-based frontline therapy, noting that published retrospective studies have reported remission rates of only around 13 percent and median overall survival of approximately 2.4 months following salvage treatment. While the current subgroup analysis is descriptive and based on a limited number of patients, Moleculin believes the consistent remission rates warrant continued investigation.

Earlier results presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting demonstrated that both Annamycin dose groups outperformed the control arm after a single treatment cycle, reinforcing the therapy's potential clinical benefit.

Annamycin, also known as naxtarubicin, has received Fast Track Designation and Orphan Drug Designation from the US Food and Drug Administration (FDA) for relapsed or refractory AML, as well as Orphan Drug Designation from the European Medicines Agency (EMA). The investigational therapy is designed to overcome multidrug resistance while avoiding the cardiotoxicity commonly associated with traditional anthracycline chemotherapy.

With enrollment nearing completion and final Part A results expected early next year, Moleculin is positioning Annamycin as a potential new treatment option for patients with relapsed or refractory AML who have limited therapeutic alternatives.