Marker Therapeutics Announces Upcoming Presentations on MT-601 in Relapsed Non-Hodgkin and Hodgkin Lymphoma at the 67th ASH Annual Meeting

Ongoing Phase 1 APOLLO study investigating MT-601 in patients with relapsed B cell lymphomas showed encouraging preliminary efficacy data

MT-601 demonstrated robust safety profile with no dose limiting toxicities (DLTs) or immune-effector cell associated neurotoxicity syndrome (ICANS ) in the dose escalation cohort

HOUSTON, Nov. 03, 2025 (GLOBE NEWSWIRE) -- Marker Therapeutics, Inc. (Nasdaq: MRKR), a clinical-stage immuno-oncology company focusing on developing next-generation T cell-based immunotherapies for the treatment of hematological malignancies and solid tumors, today announced that data from the Phase 1 APOLLO study will be presented in two posters at the 67 th American Society of Hematology (ASH) Annual Meeting and Exposition, to be held from December 6-9, 2025, in Orlando, Florida.

“We are excited to highlight the promising findings from our Phase 1 APOLLO study at the ASH Meeting,” said Juan Vera, M.D., President and Chief Executive Officer of Marker Therapeutics. “The safety and efficacy data underscore the potential of MT-601 in heavily pre-treated patients with B cell lymphomas, who have relapsed after multiple lines of therapy, including Chimeric Antigen Receptor (CAR)-T cells and bispecific antibodies.”

The Phase 1 APOLLO study (clinicaltrials.gov identifier: NCT05798897) is a multicenter, open-label trial investigating MT-601, a Multi-Antigen Recognizing (MAR)-T cell therapy, in patients with B cell lymphomas. Among patients with Non-Hodgkin lymphoma (NHL), including those who relapsed after anti-CD19 directed CAR-T cell therapy, the objective response rate (ORR) was 66% (8 out of 12) with 50% achieving a complete response (CR). Responses were durable, ranging from 3 to 24 months, with five patients remaining in remission for 6 months or longer, including three patients with responses exceeding 12 months. In Hodgkin lymphoma (HL), the ORR was 78% (7 out of 9), with 11% achieving a CR. MT-601 was well tolerated by all study participants, with no reported dose limiting toxicities or ICANS. Only two participants experienced Grade 1 cytokine release syndrome (CRS) (fever; no treatment was required).

“We are encouraged by the robust safety profile and the potential clinical benefit we continue to observe across multiple histologies, highlighting the versatility of MT-601,” commented Dr. Vera. “Based on these favorable safety and efficacy outcomes, we have now advanced to the dose expansion phase, evaluating MT-601 at the highest dose level (400x10 6 cells) in patients with Diffuse Large B Cell Lymphoma (DLBCL) who have relapsed after anti-CD19 CAR-T therapy or are ineligible for CAR-T treatment. We look forward to sharing our continued progress and engaging with the scientific and clinical community at ASH.”

Poster Presentation Details: Safety and Efficacy of MT-601 in Relapsed or Refractory (r/r) Hodgkin Lymphoma Presenting Author: Haitham Abdelhakim, M.D. (University of Kansas Medical Center, Kansas City, KS) Publication Number: 1846 Session Name: 624. Hodgkin Lymphomas: Clinical and Epidemiological: Poster I Session Date & Time: December 6, 2025 at 5:30 – 7:30 pm ET Room: OCCC – West Halls B3-B4

MT-601 Demonstrates Favorable Safety and Durable Responses in Relapsed or Refractory (r/r) Non-Hodgkin Lymphoma (NHL) Presenting Author: Geoffrey Shouse, D.O., Ph.D. (City of Hope National Medical Center, Duarte, CA) Publication Number: 5944 Session Name: 704. Cellular Immunotherapies: Early Phase Clinical Trials and Toxicities: Poster III Session Date & Time: December 8, 2025 at 6:00 – 8:00 pm ET Room: OCCC – West Halls B3-B4

About MT-601 The Company’s lead product, MT-601, is a multi-antigen recognizing (MAR) T cell product that utilizes a non-genetically modified approach that specifically targets six different tumor antigens upregulated in lymphoma cells (Survivin, PRAME, WT-1, NY-ESO-1, SSX-2, MAGEA-4). Marker is currently investigating MT-601 in the Company-sponsored Phase 1 APOLLO trial (clinicaltrials.gov identifier: NCT05798897) for the treatment of patients with lymphoma who have relapsed after or are not candidates for anti-CD19 CAR-T cell therapies.

About APOLLO The APOLLO trial (clinicaltrials.gov Identifier: NCT05798897) is a Phase 1, multicenter, open-label study designed to evaluate the safety and efficacy of MT-601 in participants with relapsed or refractory lymphoma who have either failed anti-CD19 chimeric antigen receptor (CAR) T cell therapy or are not candidates for anti-CD19 CAR-T cell therapy. The primary objective of this exploratory Phase 1 clinical trial is to evaluate the optimum dose, safety, and preliminary efficacy of MT-601 in participants with various lymphoma subtypes. The APOLLO study is supported by the National Cancer Institute of the National Institutes of Health under Award Number R44CA291521.

About MAR-T cells The multi-antigen recognizing (MAR) T cell platform (formerly known as multiTAA-specific T cells) is a novel, non-genetically modified cell therapy approach that selectively expands tumor-specific T cells from a patient's/donor’s blood capable of recognizing a broad range of tumor antigens. Unlike other T cell therapies, MAR-T cells allow the recognition of hundreds of different epitopes within up to six tumor-specific antigens, thereby reducing the possibility of tumor escape. Since MAR-T cells are not genetically engineered, Marker believes that its product candidates will be easier and less expensive to manufacture, with an improved safety profile compared to current engineered T cell approaches and may provide patients with meaningful clinical benefits.

About Marker Therapeutics, Inc. Marker Therapeutics, Inc. is a Houston, TX-based clinical-stage immuno-oncology company specializing in the development of next-generation T cell-based immunotherapies for the treatment of hematological malignancies and solid tumors. The Company was founded at Baylor College of Medicine, and clinical trials that enrolled more than 200 patients across various hematological and solid tumor indications showed that the Company’s autologous and allogeneic MAR-T cell products were well tolerated and demonstrated durable clinical responses. Marker’s goal is to introduce novel T cell therapies to the market and improve patient outcomes. To achieve these objectives, the Company prioritizes the preservation of financial resources and focuses on operational excellence. Marker’s unique T cell platform is strengthened by non-dilutive funding from U.S. state and federal agencies supporting cancer research.

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Forward-Looking Statements This release contains forward-looking statements for purposes of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Statements in this news release concerning the Company’s expectations, plans, business outlook or future performance, and any other statements concerning assumptions made or expectations as to any future events, conditions, performance or other matters, are “forward-looking statements.” Forward-looking statements include statements regarding our intentions, beliefs, projections, outlook, analyses or current expectations concerning, among other things: our research, development and regulatory activities and expectations relating to our non-engineered multi-tumor antigen specific T cell therapies; the effectiveness of these programs or the possible range of application and potential curative effects and safety in the treatment of diseases; and the timing, conduct, interim results announcements and outcomes of our clinical trials of our product candidates, including MT-601 for the treatment of patients with lymphoma. Forward-looking statements are by their nature subject to risks, uncertainties and other factors which could cause actual results to differ materially from those stated in such statements. Such risks, uncertainties and factors include, but are not limited to the risks set forth in the Company’s most recent Form 10-K, 10-Q and other SEC filings which are available through EDGAR at WWW.SEC.GOV . The Company assumes no obligation to update its forward-looking statements whether as a result of new information, future events or otherwise, after the date of this press release except as may be required by law.

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