Initiative Builds on Checkpoint Inhibitor Momentum and Landmark KEYNOTE-689 Results

ATLANTA, GA - September 24, 2025 (NEWMEDIAWIRE) - GeoVax Labs, Inc. (Nasdaq: GOVX), a clinical-stage biotechnology company developing vaccines and immunotherapies against cancers and infectious diseases, today announced the expansion of its oncology development strategy to include assessments of additional solid tumor targets for Gedeptin®, its gene-directed enzyme prodrug therapy (GDEPT).

Working closely with its oncology advisory team including the Winship Cancer Institute of Emory University, GeoVax is evaluating the combination of Gedeptin with immune checkpoint inhibitors in preclinical models of several solid tumor types. These models are designed to validate Gedeptin’s mechanism - localized intratumoral cytotoxicity that also primes systemic immune responses - in tumor settings beyond head and neck cancer such as triple negative breast cancer and cutaneous malignancies.

Phase 2 Clinical Trial

GeoVax previously announced updated plans for a Phase 2 clinical trial, AdPNP-203, which will evaluate the addition of intra-tumoral Gedeptin® and intravenous fludarabine to recently approved neoadjuvant pembrolizumab as first-line treatment of patients with head and neck squamous cell carcinoma eligible for curative surgery. The trial is designed to assess major pathological response (MPR) and associated immunologic and biomarker outcomes following two pre-surgical cycles of therapy, as well as event-free survival over a one-year period. Gedeptin’s tumor-targeting, immune-sensitizing mechanism may help overcome the limitations of checkpoint monotherapy by enhancing immune activation within the tumor microenvironment. Trial initiation is planned for the second half of 2026.

Strategic Rationale

• Checkpoint synergy: Gedeptin directly debulks tumors and enhances immune visibility, positioning it as a potential force multiplier for checkpoint inhibitors.
• Therapeutic expansion: Success in these preclinical programs could support Gedeptin’s clinical evaluation into additional solid tumors.
• Timely alignment: The KEYNOTE-689 trial demonstrated the transformative potential of neoadjuvant checkpoint therapy in head and neck cancer, underscoring the urgency and timeliness of expanding combination approaches such as Gedeptin plus Keytruda into additional tumor types.

David A. Dodd, Chairman & CEO of GeoVax, commented: “We view the expansion of Gedeptin development beyond head and neck cancer as addressing a critically important area of solid tumor cancer therapy and a major value-creation opportunity. By leveraging the strengths of our oncology advisors and validated checkpoint inhibitor backbones, we aim to evaluate that Gedeptin’s tumor-debulking and immune-priming effects can potentially improve outcomes in a broader range of solid tumor cancers. The KEYNOTE-689 results provide important context, showing how immune-sensitizing strategies like Gedeptin are increasingly vital to maximizing checkpoint efficacy.”

Dr. Kelly T. McKee, Chief Medical Officer, added: “Our preclinical efforts will provide in-vivo proof of concept for expanding Gedeptin-checkpoint inhibitor combination therapy into additional solid tumor types. This is a natural evolution of our program and ensures we remain positioned at the forefront of immuno-oncology innovation.”

Next Steps

GeoVax anticipates early readouts from its preclinical modeling work, with the results supporting the design of potential clinical trials in selected solid tumor indications. In parallel, the Company is targeting the initiation of its Phase 2 clinical trial of Gedeptin in combination with Keytruda for head and neck cancer in the second half of 2026. Potential collaborative discussions continue, with the expectation of some form of partnership or collaboration to occur relative to both the clinical development and the potential commercialization of Gedeptin.

About Gedeptin®

Gedeptin® is a gene-directed enzyme prodrug therapy (GDEPT) delivered intratumorally using a non-replicating adenoviral vector encoding purine nucleoside phosphorylase (PNP). Following administration of fludarabine, the PNP enzyme converts it into a cytotoxic compound within the tumor microenvironment, selectively destroying cancer cells while releasing antigens that enhance immune recognition. Gedeptin has been granted Orphan Drug Designation for oral and pharyngeal cancers.

About GeoVax

GeoVax Labs, Inc. is a clinical-stage biotechnology company developing novel vaccines against infectious diseases and therapies for solid tumor cancers. The Company’s lead clinical program is GEO-CM04S1, a next-generation COVID-19 vaccine currently in three Phase 2 clinical trials, being evaluated as (1) a primary vaccine for immunocompromised patients such as those suffering from hematologic cancers and other patient populations for whom the current authorized COVID-19 vaccines are insufficient, (2) a booster vaccine in patients with chronic lymphocytic leukemia (CLL) and (3) a more robust, durable COVID-19 booster among healthy patients who previously received the mRNA vaccines. In oncology the lead clinical program is evaluating a novel oncolytic solid tumor gene-directed therapy, Gedeptin®, having recently completed a multicenter Phase 1/2 clinical trial for advanced head and neck cancers. GeoVax is also developing a vaccine targeting Mpox and smallpox and, based on recent EMA regulatory guidance, anticipates progressing directly to a Phase 3 clinical evaluation, omitting Phase 1 and Phase 2 trials. GeoVax has a strong IP portfolio in support of its technologies and product candidates, holding worldwide rights for its technologies and products. For more information about the current status of our clinical trials and other updates, visit our website: www.geovax.com.

Forward-Looking Statements

This release contains forward-looking statements regarding GeoVax’s business plans. The words “believe,” “look forward to,” “may,” “estimate,” “continue,” “anticipate,” “intend,” “should,” “plan,” “could,” “target,” “potential,” “is likely,” “will,” “expect” and similar expressions, as they relate to us, are intended to identify forward-looking statements. We have based these forward-looking statements largely on our current expectations and projections about future events and financial trends that we believe may affect our financial condition, results of operations, business strategy and financial needs. Actual results may differ materially from those included in these statements due to a variety of factors, including whether: GeoVax is able to obtain acceptable results from ongoing or future clinical trials of its investigational products, GeoVax’s immuno-oncology products and preventative vaccines can provoke the desired responses, and those products or vaccines can be used effectively, GeoVax’s viral vector technology adequately amplifies immune responses to cancer antigens, GeoVax can develop and manufacture its immuno-oncology products and preventative vaccines with the desired characteristics in a timely manner, GeoVax’s immuno-oncology products and preventative vaccines will be safe for human use, GeoVax’s vaccines will effectively prevent targeted infections in humans, GeoVax’s immuno-oncology products and preventative vaccines will receive regulatory approvals necessary to be licensed and marketed, GeoVax raises required capital to complete development, there is development of competitive products that may be more effective or easier to use than GeoVax’s products, GeoVax will be able to enter into favorable manufacturing and distribution agreements, and other factors, over which GeoVax has no control.

Further information on our risk factors is contained in our periodic reports on Form 10-Q and Form 10-K that we have filed and will file with the SEC. Any forward-looking statement made by us herein speaks only as of the date on which it is made. Factors or events that could cause our actual results to differ may emerge from time to time, and it is not possible for us to predict all of them. We undertake no obligation to publicly update any forward-looking statement, whether as a result of new information, future developments or otherwise, except as may be required by law.

Company Contact:
info@geovax.com
678-384-7220

Media Contact:
Jessica Starman
media@geovax.com