On March 26, 2019 Moleculin Biotech, Inc., (Nasdaq: MBRX) ("Moleculin" or the "Company"), a clinical stage pharmaceutical company with a broad portfolio of drug candidates targeting highly resistant tumors, reported positive interim safety and efficacy data from two ongoing open label, single arm Phase 1/2 studies of Annamycin. In the first study, being conducted in the US, four patients have completed treatment at 100 mg/m2 with no significant adverse events related to Annamycin, and the study will now proceed to the next higher dose of 120 mg/m2 (Press release, Moleculin, MAR 26, 2019, https://www.prnewswire.com/news-releases/moleculin-announces-positive-interim-results-in-first-cohort-of-phase-12-clinical-studies-of-annamycin-in-acute-myeloid-leukemia-in-the-us-and-in-poland-300818195.html [SID1234534636]). The second trial, taking place in Poland, started at a 120 mg/m2 dose of Annamycin and has treated three patients. The first patient treated in that trial received a single course of Annamycin and his bone marrow blasts have reduced from 60% to 11%. Our principal investigator considers this response sufficient for the patient to proceed to consolidation therapy, with the goal of receiving a potentially curative bone marrow transplant. To date in Poland, one patient experienced grade 2 mucositis (which resolved to grade 1 within 2 days) and no other adverse events related to Annamycin have been reported. Trial results for the other two patients treated in Poland will not be known until the second quarter of this year.
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"We are very pleased to have completed the treatment of patients in cohort 1 of the US trial and move to the next higher dose," commented Walter Klemp, Moleculin’s Chairman and CEO. "In Poland, we are pleased to have such a positive response at the starting dose level in this trial. Of course the response of a single patient doesn’t necessarily predict the outcome of the trial, but this is a great way to begin and it’s consistent with our expectations for Annamycin."
Mr. Klemp continued: "One of the advantages we believe Annamycin will offer is a lack of cardiotoxicity. We have seen no evidence of cardiotoxicity in any of the patients treated thus far. We intend to advance the clinical study of Annamycin with the goal of ultimately demonstrating the drug’s safety and effectiveness to support regulatory approval in the US and European Union."
Dr. Robert Shepard, Moleculin’s Chief Medical Officer for Annamycin added: "A prior clinical trial for Annamycin in acute leukemia demonstrated activity at its Maximum Tolerable Dose of 150 mg/m2, so we are pleased for the US trial to move to the next higher dose in cohort 2 of 120 mg/m2. In Poland, we consider reducing bone marrow blasts for Patient 1 down to 11% with a single course of Annamycin to be very encouraging. Of course, significant additional study is necessary to definitively demonstrate causality."
"We have begun a second course of Annamycin as a consolidation phase for Patient 1," commented Dr. Lidia Gil, Principal Investigator in the Polish Annamycin clinical trial. "Considering that this patient was refractory to standard of care induction therapy, I am very pleased to see that Annamycin appears to be showing activity. While this is considered a ‘Partial Response,’ I believe it’s enough of a reduction to serve as a ‘bridge to transplant’ for this patient. Importantly, with the first course of Annamycin, no toxicities have been observed that would limit continued dosing with Annamycin."
Study Design
The Company is studying Annamycin in both the US and Poland in open label, single arm clinical trials to assess the safety and efficacy of Annamycin for the treatment of adults with relapsed or refractory acute myeloid leukemia. Both the US and Polish trials have the same study design, providing for a Phase 1 intended to establish a "Recommended Phase 2 Dose," ("RP2D") with cohorts of 3 patients each where the first cohort starts at a low beginning dose and each successive cohort receives the next higher dose level until "dose limiting toxicities" prevent further increases. In the case of cohort 1 in the US, one patient did not complete the evaluation protocol, so a fourth patient was added to complete that cohort.
A key difference in the US is that the starting dose was 100 mg/m2, whereas, in Poland, the starting dose was 120 mg/m2. Having completed the first cohort in the US, the Company is seeking patients for the second cohort at a dose level of 120 mg/m2. Once 3 patients have completed the safety evaluation period of the first cohort in Poland, the second cohort will begin there at a dose level of 150 mg/m2. Once the Company establishes an RP2D, the intent is for each trial to advance to a Phase 2 arm planned to assess the safety and efficacy of Annamycin in 21 additional patients.
The US trial also differs from the Polish trial in that the FDA would like to review safety data relating to cardiotoxicity from patients treated prior to advancing beyond 120 mg/m2. The Company believes that the additional patient safety data gained from the Polish trial may also assist in the FDA’s review of cardiac safety.