Ateganosine

Part C domestic enrollment is underway at three clinical sites in the U.S. CHICAGO, June 25, 2026 (GLOBE NEWSWIRE) -- MAIA Biotechnology, Inc. (NYSE American: MAIA) (“MAIA”, the “Company”), a clinical-stage biopharmaceutical company focused on developing targeted immunotherapies for cancer, today announced that it has completed international enrollment in Part C of its Phase 2 THIO-101 expansion trial evaluating its lead candidate, ateganosine, in advanced non-small cell lung cancer (NSCLC) patients receiving third line (3L) therapy. Ateganosine is an investigational dual-mechanism therapy targeting telomeres and immune activation in difficult-to-treat cancers. THIO-101 Part C patients, who are resistant to prior checkpoint inhibitor (CPI) therapy and chemotherapy, are randomized between MAIA’s proposed combination regimen of ateganosine followed by cemiplimab (Libtayo ® ) and treatment with ateganosine alone for two cycles. International screening was conducted in Taiwan, Turkey, Poland, Hungary, Romania and Georgia, with 41 patients enrolled and receiving treatment. The Part C study is currently screening patients at multiple clinical sites in the United States. “We greatly appreciate the dedication and contributions of the investigators supporting our THIO-101 trial,” said Vlad Vitoc, Founder and Chief Executive Officer of MAIA Biotechnology. “With enrollment now complete at the international Part C clinical sites, we are closely monitoring patient outcomes as the data continues to mature, including key efficacy measures such as disease control rate and overall survival, which have remained central endpoints throughout the Phase 2 THIO-101 trial. Meanwhile, patient screening is ongoing at three activated clinical sites in the United States.” In Parts A and B of THIO-101, MAIA reported data showing median survival of 17.8 months. Overall survival (OS) beyond two years was observed for eight patients in Parts A and B of THIO-101; the patients did not receive subsequent lines of therapy. One patient in this cohort receiving 3L therapy has survived for over 33 months. Expected survival in this heavily pre-treated population is 5.8 months. 1 The FDA has granted Fast Track designation for ateganosine in NSCLC treatment, potentially expediting the regulatory process to a potential Accelerated Approval and Priority Review. About Ateganosine Ateganosine (THIO, 6-thio-dG or 6-thio-2’-deoxyguanosine) is a first-in-class investigational telomere-targeting agent currently in clinical development to evaluate its activity in non-small cell lung cancer (NSCLC). Telomeres, along with the enzyme telomerase, play a fundamental role in the survival of cancer cells and their resistance to current therapies. The modified nucleotide 6-thio-2’-deoxyguanosine induces telomerase-dependent telomeric DNA modification, DNA damage responses, and selective cancer cell death. Ateganosine-damaged telomeric fragments accumulate in cytosolic micronuclei and activates both innate (cGAS/STING) and adaptive (T-cell) immune responses. The sequential treatment of ateganosine followed by PD-(L)1 inhibitors resulted in profound and persistent tumor regression in advanced, in vivo cancer models by induction of cancer type–specific immune memory. Ateganosine is presently developed as a second or later line of treatment for NSCLC for patients that have progressed beyond the standard-of-care regimen of existing checkpoint inhibitors. About THIO-101 Phase 2 Clinical Trial THIO-101 is a multicenter, open-label, dose finding Phase 2 clinical trial. It is the first trial designed to evaluate ateganosine’s anti-tumor activity when followed by PD-(L)1 inhibition. The trial is testing the hypothesis that low doses of ateganosine administered prior to cemiplimab (Libtayo ® ) will enhance and prolong immune response in patients with advanced NSCLC who previously did not respond or developed resistance and progressed after first-line treatment regimen containing another checkpoint inhibitor. The trial design has two primary objectives: (1) to evaluate the safety and tolerability of ateganosine administered as an anticancer compound and a priming immune activator (2) to assess the clinical efficacy of ateganosine using Overall Response Rate (ORR) as the primary clinical endpoint. The expansion of the study will assess overall response rates (ORR) in advanced NSCLC patients receiving third line (3L) therapy who were resistant to previous checkpoint inhibitor treatments (CPI) and chemotherapy. Treatment with ateganosine followed by cemiplimab (Libtayo ® ) has shown an acceptable safety pro date in a heavily pre-treated population. For more information on this Phase II trial, please visit ClinicalTrials.gov using the identifier NCT05208944. About MAIA Biotechnology, Inc. MAIA is a targeted therapy, immuno-oncology company focused on the development and commercialization of potential first-in-class drugs with novel mechanisms of action that are intended to meaningfully improve and extend the lives of people with cancer. Our lead program is ateganosine (THIO), a potential first-in-class cancer telomere targeting agent in clinical development for the treatment of NSCLC patients with telomerase-positive cancer cells. For more information, please visit . Forward Looking Statements MAIA cautions that all statements, other than statements of historical facts contained in this press release, are forward-looking statements. Forward-looking statements are subject to known and unknown risks, uncertainties, and other factors that may cause our or our industry’s actual results, levels or activity, performance or achievements to be materially different from those anticipated by such statements. The use of words such as “may,” “might,” “will,” “should,” “could,” “expect,” “plan,” “anticipate,” “believe,” “estimate,” “project,” “intend,” “future,” “potential,” or “continue,” and other similar expressions are intended to identify forward looking statements. However, the absence of these words does not mean that statements are not forward-looking. For example, all statements we make regarding (i) the initiation, timing, cost, progress and results of our preclinical and clinical studies and our research and development programs, (ii) our ability to advance product candidates into, and successfully complete, clinical studies, (iii) the timing or likelihood of regulatory filings and approvals, (iv) our ability to develop, manufacture and commercialize our product candidates and to improve the manufacturing process, (v) the rate and degree of market acceptance of our product candidates, (vi) the size and growth potential of the markets for our product candidates and our ability to serve those markets, and (vii) our expectations regarding our ability to obtain and maintain intellectual property protection for our product candidates, are forward looking. All forward-looking statements are based on current estimates, assumptions and expectations by our management that, although we believe to be reasonable, are inherently uncertain. Any forward-looking statement expressing an expectation or belief as to future events is expressed in good faith and believed to be reasonable at the time such forward-looking statement is made. However, these statements are not guarantees of future events and are subject to risks and uncertainties and other factors beyond our control that may cause actual results to differ materially from those expressed in any forward-looking statement. Any forward-looking statement speaks only as of the date on which it was made. We undertake no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise, except as required by law. In this release, unless the context requires otherwise, “MAIA,” “Company,” “we,” “our,” and “us” refers to MAIA Biotechnology, Inc. and its subsidiaries. Investor Relations Contact +1 (872) 270-3518 ir@maiabiotech.com 1 Girard N, et al. J Thorac Onc 2009;12:1544-1549

Georgia’s only National Cancer Institute (NCI)-designated Comprehensive Cancer Center; well recognized at the forefront of cancer innovation and discovery nationwide CHICAGO, June 18, 2026 (GLOBE NEWSWIRE) -- MAIA Biotechnology, Inc. (NYSE American: MAIA) (“MAIA”, the “Company”), a clinical-stage biopharmaceutical company focused on developing targeted immunotherapies for cancer, today announced that the third U.S. clinical site in its Phase 2 THIO-101 expansion trial, Winship Cancer Institute of Emory University (“Winship”), is activated and now enrolling patients. The trial studies MAIA’s lead investigational telomere-targeting agent, ateganosine, as a third-line (3L) treatment for non-small cell lung cancer (NSCLC). Matthew Failor, Director of Clinical Operations for MAIA, commented, “Winship is Georgia's only National Cancer Institute (NCI)-designated Comprehensive Cancer Center and is recognized at the forefront of cancer innovation and discovery nationwide. Winship offers a renowned thoracic oncology clinical research program with a proven track record in clinical trial development and conduct. With its premier medical team and extensive body of research, this cancer center is well-suited for our U.S. Phase 2 trial of ateganosine.” The principal investigator for the THIO-101 expansion trial at Winship is Ticiana Leal, M.D., a professor in the Department of Hematology and Medical Oncology at the Emory University School of Medicine. Dr. Leal’s clinical research focuses on trials involving chemotherapy and immunotherapy agents for lung cancer. Dr. Leal commented, “At Winship, we serve the state of Georgia and surrounding states where innovation in lung cancer treatment is a broad, underserved need. In Georgia, lung cancer is the leading cause of cancer-related deaths, with over 7,300 new cases in 2025. MAIA’s novel ateganosine agent, if approved, could address a significant gap in clinical care for the advanced-stage NSCLC patient population where there are no FDA-approved options available for treatment.” THIO-101 is an ongoing Phase 2, open-label trial evaluating ateganosine followed by cemiplimab for NSCLC patients resistant to checkpoint inhibitors and chemotherapy. Parts A and B of the trial have shown strong early efficacy, with some patients showing survival exceeding two years, and now MAIA continues to expand the trial in the U.S. About Ateganosine Ateganosine (THIO, 6-thio-dG or 6-thio-2’-deoxyguanosine) is a first-in-class investigational telomere-targeting agent currently in clinical development to evaluate its activity in non-small cell lung cancer (NSCLC). Telomeres, along with the enzyme telomerase, play a fundamental role in the survival of cancer cells and their resistance to current therapies. The modified nucleotide 6-thio-2’-deoxyguanosine induces telomerase-dependent telomeric DNA modification, DNA damage responses, and selective cancer cell death. Ateganosine-damaged telomeric fragments accumulate in cytosolic micronuclei and activates both innate (cGAS/STING) and adaptive (T-cell) immune responses. The sequential treatment of ateganosine followed by PD-(L)1 inhibitors resulted in profound and persistent tumor regression in advanced, in vivo cancer models by induction of cancer type–specific immune memory. Ateganosine is presently developed as a second or later line of treatment for NSCLC for patients that have progressed beyond the standard-of-care regimen of existing checkpoint inhibitors. About THIO-101 Phase 2 Clinical Trial THIO-101 is a multicenter, open-label, dose finding Phase 2 clinical trial. It is the first trial designed to evaluate ateganosine’s anti-tumor activity when followed by PD-(L)1 inhibition. The trial is testing the hypothesis that low doses of ateganosine administered prior to cemiplimab (Libtayo®) will enhance and prolong immune response in patients with advanced NSCLC who previously did not respond or developed resistance and progressed after first-line treatment regimen containing another checkpoint inhibitor. The trial design has two primary objectives: (1) to evaluate the safety and tolerability of ateganosine administered as an anticancer compound and a priming immune activator (2) to assess the clinical efficacy of ateganosine using Overall Response Rate (ORR) as the primary clinical endpoint. The expansion of the study will assess overall response rates (ORR) in advanced NSCLC patients receiving third line (3L) therapy who were resistant to previous checkpoint inhibitor treatments (CPI) and chemotherapy. Treatment with ateganosine followed by cemiplimab (Libtayo®) has shown an acceptable safety profile to date in a heavily pre-treated population. For more information on this Phase II trial, please visit ClinicalTrials.gov using the identifier NCT05208944. About MAIA Biotechnology, Inc. MAIA is a targeted therapy, immuno-oncology company focused on the development and commercialization of potential first-in-class drugs with novel mechanisms of action that are intended to meaningfully improve and extend the lives of people with cancer. Our lead program is ateganosine (THIO), a potential first-in-class cancer telomere targeting agent in clinical development for the treatment of NSCLC patients with telomerase-positive cancer cells. For more information, please visit www.maiabiotech.com. Forward Looking Statements MAIA cautions that all statements, other than statements of historical facts contained in this press release, are forward-looking statements. Forward-looking statements are subject to known and unknown risks, uncertainties, and other factors that may cause our or our industry’s actual results, levels or activity, performance or achievements to be materially different from those anticipated by such statements. The use of words such as “may,” “might,” “will,” “should,” “could,” “expect,” “plan,” “anticipate,” “believe,” “estimate,” “project,” “intend,” “future,” “potential,” or “continue,” and other similar expressions are intended to identify forward looking statements. However, the absence of these words does not mean that statements are not forward-looking. For example, all statements we make regarding (i) the initiation, timing, cost, progress and results of our preclinical and clinical studies and our research and development programs, (ii) our ability to advance product candidates into, and successfully complete, clinical studies, (iii) the timing or likelihood of regulatory filings and approvals, (iv) our ability to develop, manufacture and commercialize our product candidates and to improve the manufacturing process, (v) the rate and degree of market acceptance of our product candidates, (vi) the size and growth potential of the markets for our product candidates and our ability to serve those markets, and (vii) our expectations regarding our ability to obtain and maintain intellectual property protection for our product candidates, are forward looking. All forward-looking statements are based on current estimates, assumptions and expectations by our management that, although we believe to be reasonable, are inherently uncertain. Any forward-looking statement expressing an expectation or belief as to future events is expressed in good faith and believed to be reasonable at the time such forward-looking statement is made. However, these statements are not guarantees of future events and are subject to risks and uncertainties and other factors beyond our control that may cause actual results to differ materially from those expressed in any forward-looking statement. Any forward-looking statement speaks only as of the date on which it was made. We undertake no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise, except as required by law. In this release, unless the context requires otherwise, “MAIA,” “Company,” “we,” “our,” and “us” refers to MAIA Biotechnology, Inc. and its subsidiaries. Investor Relations Contact+1 (872) 270-3518ir@maiabiotech.com