Moleculin Biotech, Inc. provided a preliminary update on recent clinical activity and expected near term milestones for its lead program MB-106 for the treatment of Acute Myeloid Leukemia (AML) following its Fiscal Year 2023 filing with the Securities and Exchange Commission. During 2023, Moleculin commenced its MB-106 clinical trial with AnnAraC for the treatment of AML in an all-comers trial, accepting subjects without regard to the number of prior therapies in the Phase 1 portion with a limit of two prior therapies in the Phase 2 portion. Nine clinical sites in Poland and Italy have been activated for the MB-106.

To date, 20 subjects have been enrolled in the full MB106 Phase 1B/2 study with two subjects not yet evaluable. At the end of January 2024, the Company completed recruiting the desired number of 2nd line subjects and began preparation for an End of Phase 2 (EoP2) meeting with the FDA. In addition, Moleculin expanded the MB-106 study protocol to include 1st line subjects to provide data to enable the designing of a potential confirmatory Phase 3 post-approval study, however, do not expect the addition of this cohort to delay the EoP2 meeting.

The study has recruited three 1st line subjects to date with one CR and one not yet evaluable. Moleculin's current planned pathway for approval for Annamycin in combination with Cytarabine for the treatment of AML is as a 2nd line therapy. Therefore, the focus is primarily on securing an accelerated approval pathway for the treatment of 2nd line subjects (those who were relapsed from or refractory to a 1st line AML therapy, regardless as to whether the subject was deemed "fit" or "unfit").

Moleculin has begun recruiting 1st line subjects into this trial to provide data for a possible future confirmatory Phase 3 clinical trial in 1st line patients. Summary table of the MB-106 preliminary results, which are subject to change, is shown below. The total CRs in both Phases to date in MB-106 represent a complete response composite (CRc) rate of 39% in all currently evaluable, intent to treat subjects (n= 18) with two additional subjects recruited not yet evaluable.

These subjects had 0-6 prior therapies. This is comprised of a CR rate of 33% and CRi of 6%. Durability data are developing with one CRc having relapsed to date.

The first CR subject was treated in February 2023 and remains durable after over a year and continues in remission. Durability of CRs is confirmed by repeat bone marrow aspirates (BMAs). The median age of all subjects recruited is 69, ranging from 19 to 78.

Median durability will be established as the trial data mature. This trial may enroll up to 28 subjects, however, having already recruited the desired number of 2nd line subjects to support an EoP2 meeting with the FDA, the Company may elect to complete this trial with fewer than 28 subjects. The trial continues recruitment for treatment as 1st line and 3rd line therapy.

Since Moleculin intends to position AnnAraC for approval as a 2nd line therapy, the Company believes that the most important data from this trial are the results in 2nd line subjects (excluding subjects who are either 1st line or 3rd line and beyond). When stratified for that population (n=10), the CRc rate is 60%, being comprised of a CR rate of 50% and a CRi of 10%.