MB-104

Data published in peer-reviewed British Journal of Cancer Research No evidence of cardiotoxicity in any subject treated in this study, including up to 16 subjects whose cumulative anthracycline dose (Annamycin included) exceeded the lifetime cumulative doxorubicin (or equivalent) dose of > 450 mg/m2 After experiencing an 80%/60% ORR/CRi rates in last single agent cohort, Annamycin is currently being evaluated in a Phase 1b/2 study in combination with Cytarabine for the treatment of AML HOUSTON, July 13, 2023 /PRNewswire/ --Moleculin Biotech, Inc., (Nasdaq: MBRX) (Moleculin or the Company), a clinical stage pharmaceutical company with a broad portfolio of drug candidates targeting hard-to-treat tumors and viruses, today announced the publication of data from its completed MB-105 European Phase 1 clinical trial assessing the safety and efficacy of Annamycin as a single agent for the treatment of adults with relapsed or refractory AML. The manuscript titled, "Results of a Phase 1 Study of Liposomal Annamycin for the Treatment of Relapsed or Refractory AML Patients After Induction Therapy," was published in the peer-reviewed British Journal of Cancer Research. The authors of the published manuscript include Dr. Wolfram Dempke (Moleculin's European Chief Medical Officer), Dr. John Paul Waymack (Moleculin's Senior Chief Medical Officer) and Dr. Waldemar Priebe (Moleculin's Chair - Scientific Advisory Board), as well as Polish investigators from the MB-105 trial. "We are pleased to have the data from our successful MB-105 study published in this prestigious journal," commented Walter Klemp, Chairman and CEO of Moleculin. "This early data provided an important foundation for our AML program and was informative for guiding our clinical development strategy for Annamycin in combination with Cytarabine for the treatment of AML. We continue to be very optimistic about Annamycin's potential to provide a non-cardiotoxic treatment option for patients." MB-105 is the Company's completed multicenter, open-label, dose-escalation study which was conducted to determine the maximal tolerated dose (MTD) and recommended Phase 2 dose (RP2D) of Annamycin as a single agent for the treatment of patients with AML after induction therapy. A total of 20 subjects with the age range of 24-76 years with a median age of 64.5 were enrolled across five clinical trial sites in Europe. The median number of prior therapies for all subjects was 4 (range 1-18). Of the 20 subjects enrolled, 17 received the full 3 consecutive days of dosing per protocol. As previously announced, the final MB-105 results aligned with the overall safety pro Annamycin and observations made in previously completed and ongoing clinical studies evaluating Annamycin. Additionally, as detailed in the paper, among the eight subjects treated in the final dosing cohort (240 mg/m2) five were evaluable for efficacy and there were one PRs (Partial Response) and three CRi (complete response with incomplete recovery of peripheral blood count) among these five subjects, representing an 80% overall response rate (ORR) in the last cohort. For purposes of this clinical trial, a CR means that the subject's bone marrow blasts reduced to 5% or less (with CRi meaning a CR where there was incomplete recovery of white blood cell and/or platelet counts), and a PR means the subject's bone marrow blasts reduced by 50% and resulted in a blast count of 25% or less. Annamycin again demonstrated no evidence of cardiotoxicity based on review of cardiotoxicity biomarkers, LVEF, and ECHO GLS evaluation. These properties differentiate Annamycin from all other anthracyclines that have shown limited or no cardiotoxicity to date and highlight it as a very promising anticancer agent and it retains the ability to poison TOPO-IIα (topoisomerase II) and can also overcome mdr-1-related resistance mechanisms in leukaemic blasts, as shown in its parent compound. As announced in February 2022, upon safely reaching the RP2D of 240 mg/m2 in the MB-105 trial, the Company concluded recruitment for the trial. Based on the safety and dosage data from the two successfully concluded single agent Annamycin AML Phase 1 trials, MB-104 and MB-105, Moleculin commenced its ongoing Phase 1/2 trial evaluating Annamycin in combination with Cytarabine (Ara-C) for the treatment of subjects with AML who are refractory to or relapsed after induction therapy (MB-106) clinicaltrialsregister.eu: EudraCT 2020-005493-10 or clinicaltrials.gov: NCT05319587. Annamycin currently has Fast Track Status and Orphan Drug Designation from the U.S. Food and Drug Administration (FDA) for the treatment of STS lung metastases and the treatment of relapsed or refractory AML. About Moleculin Biotech, Inc. Moleculin Biotech, Inc. is a clinical stage pharmaceutical company with a growing pipeline, including Phase 2 clinical programs, for hard-to-treat tumors and viruses. The Company's lead program, Annamycin is a next-generation anthracycline designed to avoid multidrug resistance mechanisms with little to no cardiotoxicity. Annamycin is currently in development for the treatment of relapsed or refractory acute myeloid leukemia (AML) and soft tissue sarcoma (STS) lung metastases. Additionally, the Company is developing WP1066, an Immune/Transcription Modulator capable of inhibiting p-STAT3 and other oncogenic transcription factors while also stimulating a natural immune response, targeting brain tumors, pancreatic and other cancers, and WP1220, an analog to WP1066, for the topical treatment of cutaneous T-cell lymphoma. Moleculin is also engaged in the development of a portfolio of antimetabolites, including WP1122 for the potential treatment of COVID-19 and other viruses, as well as cancer indications including brain tumors, pancreatic and other cancers. For more information about the Company, please visit and connect on Twitter, LinkedIn and Facebook. Forward-Looking Statements Some of the statements in this release are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, Section 21E of the Securities Exchange Act of 1934 and the Private Securities Litigation Reform Act of 1995, which involve risks and uncertainties. Although Moleculin believes that the expectations reflected in such forward-looking statements are reasonable as of the date made, expectations may prove to have been materially different from the results expressed or implied by such forward-looking statements. Moleculin has attempted to identify forward-looking statements by terminology including 'believes,' 'estimates,' 'anticipates,' 'expects,' 'plans,' 'projects,' 'intends,' 'potential,' 'may,' 'could,' 'might,' 'will,' 'should,' 'approximately' or other words that convey uncertainty of future events or outcomes to identify these forward-looking statements. These statements are only predictions and involve known and unknown risks, uncertainties, and other factors, including those discussed under Item 1A. "Risk Factors" in our most recently filed Form 10-K filed with the Securities and Exchange Commission ("SEC") and updated from time to time in our Form 10-Q filings and in our other public filings with the SEC. Any forward-looking statements contained in this release speak only as of its date. We undertake no obligation to update any forward-looking statements contained in this release to reflect events or circumstances occurring after its date or to reflect the occurrence of unanticipated events. Investor Contact: JTC Team, LLC Jenene Thomas (833) 475-8247 MBRX@jtcir.com Company Codes: NASDAQ-SMALL:MBRX

Preliminary results demonstrate a durable complete response at starting dose level in elderly subject Positive results from first cohort allows Company to progress to second cohort in Phase 1b portion of the Phase 1b/2 trial with 230 mg/m2 dose of Annamycin HOUSTON, May 2, 2023 /PRNewswire/ -- Moleculin Biotech, Inc., (Nasdaq: MBRX) ("Moleculin" or the "Company"), a clinical stage pharmaceutical company with a growing pipeline, including Phase 2 clinical programs, for hard-to-treat tumors and viruses, today announced the successful completion of the first cohort in the Phase 1b portion of its Phase 1b/2 clinical trial using Annamycin in combination with Cytarabine for the treatment of AML (MB-106). In this first cohort three subjects were treated, all of whom are believed to be relapsed from multiple prior therapies. Annamycin was dosed at 190 mg/m2, along with Cytarabine at 2.0 g/m2/day for 5 days (total dose of 10 g/m2), consistent with the familiar 7+3 regimen, combining daunorubicin and Cytarabine, typically used as a first-line induction therapy. In the Company's study therapy Annamycin replaces daunorubicin. The Company, at the recommendation of the data safety committee, deemed the first cohort dose as safe and opened the second cohort with the Annamycin dose being increased to 230 mg/m2. The median of prior therapies for these three subjects were 5 (2 to 7). One of the subjects, who was 78 years of age at the time of study initiation with 2 prior multi-year therapies, was preliminarily recorded as a complete response at three weeks, or "CR", per the protocol. This was subsequently confirmed to be a durable CR after four weeks. The other two subjects were shown to have disease progression. Subjects have already been identified as potential candidates for the second cohort. "We are pleased with the rapid progress of this trial and to be advancing to the second cohort of escalated dosing. These preliminary results demonstrated by Annamycin in combination with Ara-C, add to our confidence in Annamycin's potential to be an important treatment for refractory or relapsed AML. Since it wasn't until we exceeded 210 mg/m2 in our single agent trials that we saw a consistent response rate (80%), we are glad to see a CR at just 190 mg/m2 and are eager to see how subjects respond at 230 mg/m2, especially since our preclinical animal studies showed a significant increase in activity when Annamycin is combined with Cytarabine, as it is in this trial. We are also encouraged to see a full slate of candidates already identified for the second cohort and our clinical team is working to get subject screening and dosing for this next cohort. We look forward to providing additional updates in the near future," commented Walter Klemp, Chairman and Chief Executive Officer of Moleculin. The Phase 1b/2 MB-106 trial is an open label trial that builds on the safety and dosage data from the two successfully concluded single agent Annamycin AML Phase 1 trials, MB-104 and MB-105, conducted in the U.S. and Europe, respectively. Annamycin is the Company's next-generation anthracycline that has been designed to be non-cardiotoxic and has been shown in animal models to accumulate in the lungs at up to 30-fold the level of doxorubicin (a commonly prescribed anthracycline), as well as demonstrating the ability to avoid the multidrug resistance mechanisms that typically limit the efficacy of doxorubicin and other currently prescribed anthracyclines. Annamycin is currently in development for the treatment of relapsed or refractory AML and soft tissue sarcoma (STS) lung metastases and the Company believes it may have the potential to treat additional indications. Annamycin currently has Fast Track Status and Orphan Drug Designation from the US Food and Drug Administration (FDA) for the treatment of STS lung metastases and the treatment of relapsed or refractory AML. For more information about the MB-106 Phase 1/2 trial, visit clinicaltrialsregister.eu and reference EudraCT 2020-005493-10 or clinicaltrials.gov and reference NCT05319587. About Moleculin Biotech, Inc. Moleculin Biotech, Inc. is a clinical stage pharmaceutical company with a growing pipeline, including Phase 2 clinical programs, for hard-to-treat tumors and viruses. The Company's lead program, Annamycin is a next-generation anthracycline designed to avoid multidrug resistance mechanisms with little to no cardiotoxicity. Annamycin is currently in development for the treatment of relapsed or refractory acute myeloid leukemia (AML) and soft tissue sarcoma (STS) lung metastases. Additionally, the Company is developing WP1066, an Immune/Transcription Modulator capable of inhibiting p-STAT3 and other oncogenic transcription factors while also stimulating a natural immune response, targeting brain tumors, pancreatic and other cancers, and WP1220, an analog to WP1066, for the topical treatment of cutaneous T-cell lymphoma. Moleculin is also engaged in the development of a portfolio of antimetabolites, including WP1122 for the potential treatment of COVID-19 and other viruses, as well as cancer indications including brain tumors, pancreatic and other cancers. For more information about the Company, please visit and connect on Twitter, LinkedIn and Facebook. Forward-Looking Statements Some of the statements in this release are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, Section 21E of the Securities Exchange Act of 1934 and the Private Securities Litigation Reform Act of 1995, which involve risks and uncertainties. Forward-looking statements in this release include, without limitation, the timing of future trial updates. Although Moleculin believes that the expectations reflected in such forward-looking statements are reasonable as of the date made, expectations may prove to have been materially different from the results expressed or implied by such forward-looking statements. Moleculin has attempted to identify forward-looking statements by terminology including 'believes,' 'estimates,' 'anticipates,' 'expects,' 'plans,' 'projects,' 'intends,' 'potential,' 'may,' 'could,' 'might,' 'will,' 'should,' 'approximately' or other words that convey uncertainty of future events or outcomes to identify these forward-looking statements. These statements are only predictions and involve known and unknown risks, uncertainties, and other factors, including those discussed under Item 1A. "Risk Factors" in our most recently filed Form 10-K filed with the Securities and Exchange Commission ("SEC") and updated from time to time in our Form 10-Q filings and in our other public filings with the SEC. Any forward-looking statements contained in this release speak only as of its date. We undertake no obligation to update any forward-looking statements contained in this release to reflect events or circumstances occurring after its date or to reflect the occurrence of unanticipated events. Investor Contact: JTC Team, LLC Jenene Thomas (833) 475-8247 MBRX@jtcir.com Company Codes: NASDAQ-SMALL:MBRX