Moleculin’s MIRACLE R/R AML Trial Reports Positive Interim Data with 37% Blinded CRc in Venetoclax-Failed Patients

Moleculin’s MIRACLE R/R AML Trial Reports Positive Interim Data with 37% Blinded CRc in Venetoclax-Failed Patients Prior venetoclax failure — a setting in which published salvage remission rates are approximately 13% and median survival approximately 2.4 months — shows no adverse impact on blinded composite remission rates as MIRACLE approaches the end of Part A Preliminary blinded CR of 24% and CRc of 37% (n=62), with essentially identical rates among the 30 patients who had failed first-line venetoclax: CR of 23% and CRc of 37% (3X the published salvage remission rates following first-line venetoclax failure of approximately 13%) Enrollment reaches 74 of 90 patients, with final Part A treatment expected in September 2026 and comprehensive unblinded Part A results on track for the planned December 2026–February 2027 timeframe No evidence of cardiotoxicity continues to differentiate Annamycin from conventional anthracyclines HOUSTON, July 31, 2026 (GLOBE NEWSWIRE) -- Moleculin Biotech, Inc. , (Nasdaq: MBRX) (“Moleculin” or the “Company”), today announced updated preliminary blinded results from Part A of its pivotal Phase 2/3 MIRACLE trial (MB-108) of Annamycin in combination with cytarabine (AnnAraC) for the treatment of relapsed or refractory acute myeloid leukemia (R/R AML). With 62 subjects evaluable to date, the preliminary blinded complete remission (CR) rate is 24% and the composite complete remission (CRc) rate is 37%. Of those 62 subjects, 30, or 48%, had previously received a venetoclax-based regimen. Among that subgroup, the preliminary blinded CR and CRc rates were 23% and 37%, respectively, essentially identical to the evaluable population as a whole. Walter Klemp, Chairman and Chief Executive Officer of Moleculin, commented, “Nearly half of our evaluable subjects have now entered the trial having failed prior venetoclax therapy, a group for which published salvage remission rates are approximately 13% and median survival approximately 2.4 months. Within that subgroup, our blinded CRc is also approximately 37%, indistinguishable from the evaluable population as a whole, which suggests prior venetoclax failure is not diminishing the remissions we are seeing. Because this analysis is still blinded and includes control-arm subjects, we would expect it to sit below the unblinded Annamycin-arm results we reported in June. That it has held in a narrow band while the population became measurably harder to treat is what gives us added confidence as we approach the completion of Part A.” Mr. Klemp continued, “Just as importantly, based on reported ejection fractions and adverse events, we continue to observe no evidence of cardiotoxicity, one of the defining characteristics that differentiates Annamycin from conventional anthracyclines. We believe the combination of encouraging efficacy, continued cardiac safety, and rapid enrollment progress positions MIRACLE for what could be its most important period yet.” Because this analysis remains blinded, it includes subjects randomized to the control arm and is therefore expected to be lower than the unblinded Annamycin-arm results reported at the June 2026 interim analysis, in which CRc reached 50% and 57% in the two Annamycin arms versus 29% for control. The two sets of figures are not directly comparable. Across three successive blinded analyses, at 30, 45 and 62 evaluable subjects, the blinded CRc has remained within a narrow band of approximately 37% to 40%, while the proportion of subjects entering the trial after failure of a first-line venetoclax-based regimen has risen from 31.1% in the n=45 population to 48% today. Enrollment stands at 74 of 90 subjects, and additional subjects continue to be identified by site investigators. The Company expects to treat the 90th subject in September 2026, with unblinded