GeoVax Applauds Clinical Validation of Combination Immunotherapy Strategies

Moderna-Merck Positive Phase 3 Combination Results Reinforce Strategic Rationale for Planned Gedeptin® + KEYTRUDA® Study

ATLANTA, GA - August 24, 2026 (NEWMEDIAWIRE) - GeoVax Labs, Inc. (Nasdaq: GOVX), a clinical-stage biotechnology company developing vaccines and immunotherapies for infectious diseases and solid tumors, today highlighted positive Phase 3 results reported by Moderna and Merck evaluating intismeran autogene, an individualized neoantigen therapy, in combination with KEYTRUDA® (pembrolizumab) as further evidence of an important evolution in cancer immunotherapy directly relevant to GeoVax's Gedeptin development strategy: combining checkpoint inhibition with complementary approaches designed to generate or enhance anti-tumor immune responses.

Moderna-Merck reported that the Phase 3 INTerpath-001 study in patients with completely resected high-risk melanoma met its primary endpoint of recurrence-free survival and a key secondary endpoint of distant metastasis-free survival. The combination demonstrated statistically significant and clinically meaningful improvements compared with KEYTRUDA® alone. The study is continuing to evaluate additional endpoints, including overall survival.

For GeoVax, the results have important strategic implications for the planned clinical development of Gedeptin® in combination with KEYTRUDA®. While Gedeptin and intismeran employ fundamentally different mechanisms, both strategies seek to address a common therapeutic objective: generating or enhancing an anti-tumor immune response that can be amplified by checkpoint inhibition. GeoVax believes the Phase 3 success of intismeran plus KEYTRUDA® provides important external clinical validation of this broader combination-treatment paradigm and further reinforces the rationale for advancing Gedeptin in combination with KEYTRUDA®.

“The significance of these results extends beyond any individual technology or cancer type,” said David A. Dodd, Chairman and Chief Executive Officer of GeoVax. “We believe they reinforce an increasingly important principle in immuno-oncology: checkpoint inhibitors may become substantially more effective when combined with therapies capable of generating, exposing or amplifying an anti-tumor immune response. That is the biological challenge we are seeking to address with Gedeptin®.”

Multiple Approaches Converging on a Common Immuno-Oncology Strategy

The Moderna-Merck results represent a different therapeutic approach from GeoVax's investigational Gedeptin therapy. Intismeran is designed to generate an individualized immune response against tumor-specific neoantigens, while Gedeptin utilizes a gene-directed enzyme prodrug therapy (GDEPT) designed to produce potent localized tumor destruction and promote anti-tumor immune activity within the tumor microenvironment.

Despite these mechanistic differences, GeoVax believes recent developments increasingly support a broader therapeutic strategy: combining checkpoint inhibition with complementary technologies capable of helping the immune system recognize and attack cancer.

Earlier this month, GeoVax highlighted the FDA accelerated approval of Replimune's TUDRIQEV™ in combination with nivolumab as another important milestone for tumor-directed therapies used with checkpoint inhibition.

Taken together, GeoVax believes these developments illustrate several complementary approaches now converging around a common objective:

• Personalized immune activation: individualized neoantigen therapies designed to train the immune system to recognize tumor-specific mutations;
• Tumor-directed immunotherapy: localized approaches designed to destroy tumor cells and stimulate anti-tumor immunity; and
• Tumor microenvironment priming: strategies designed to help transform immunologically resistant or “cold” tumors into tumors more responsive to checkpoint inhibition.

Gedeptin's Tumor-Priming Strategy

Gedeptin is mechanistically distinct from both individualized cancer vaccines and replication-dependent oncolytic viruses. Gedeptin utilizes a replication-deficient adenoviral vector to deliver the bacterial enzyme purine nucleoside phosphorylase (PNP) directly into tumor tissue. Following administration of fludarabine phosphate, the enzyme converts the inactive prodrug into a potent cytotoxic metabolite within the tumor microenvironment, producing localized tumor destruction with a substantial bystander effect extending beyond directly transduced tumor cells.

Importantly, GeoVax believes Gedeptin's potential therapeutic value extends beyond localized tumor killing. Recently published research in JCI Insight demonstrated that Gedeptin combined with anti-PD-1 therapy in an immunocompetent preclinical model enhanced anti-tumor immune responses, increased CD8+ T-cell infiltration, generated systemic anti-tumor activity and improved therapeutic outcomes compared with checkpoint inhibition alone. These findings support GeoVax's strategy of evaluating Gedeptin as a potential tumor-priming therapy designed to make the tumor microenvironment more favorable for checkpoint inhibition.

“Cancer immunotherapy is increasingly becoming a story about combinations,” said Kelly McKee, M.D., Chief Medical Officer of GeoVax. “Checkpoint inhibitors have transformed cancer treatment, but many tumors remain poorly responsive because the immune system has not been sufficiently activated against them. The opportunity is to create the biological conditions that allow these highly effective medicines to work in more patients. Our published Gedeptin research provides scientific support for pursuing that strategy.”

Advancing Gedeptin® in Combination with Keytruda®️ (pembrolizumab)

GeoVax is continuing preparations for the next phase of Gedeptin's clinical development in combination with KEYTRUDA® in patients with head and neck squamous cell carcinoma. The planned study is expected to evaluate clinical activity together with biomarkers of immune activation, tumor microenvironment modulation and pathological tumor response, providing an opportunity to investigate whether Gedeptin-mediated tumor priming can enhance response to checkpoint inhibition.

Mr. Dodd concluded, “Within a matter of weeks, we have seen important developments involving fundamentally different technologies but a remarkably consistent therapeutic objective: enable the patient's immune system to attack cancer more effectively and then leverage checkpoint inhibition to sustain and amplify that response. We believe this convergence provides important context for Gedeptin and reinforces the rationale for its continued clinical development.”

About Gedeptin®

Gedeptin® is GeoVax's investigational gene-directed enzyme prodrug therapy (GDEPT) for the treatment of solid tumors. The therapy utilizes a replication-deficient adenoviral vector to deliver the bacterial enzyme purine nucleoside phosphorylase (PNP) directly into tumors. Following administration of fludarabine phosphate, the PNP enzyme converts the inactive prodrug into a potent cytotoxic metabolite within the tumor microenvironment, producing localized tumor cell death while promoting anti-tumor immune responses. Gedeptin is being developed in combination with immune checkpoint inhibitors for the treatment of solid tumors.

About GeoVax

GeoVax Labs, Inc. is a clinical-stage biotechnology company focused on the development of vaccines and immunotherapies addressing high-consequence infectious diseases and solid tumor cancers. GeoVax’s priority program is GEO-MVA, a Modified Vaccinia Ankara (MVA)–based vaccine targeting mpox and smallpox. The program is advancing under an expedited regulatory pathway, with plans to initiate a pivotal Phase 3 clinical trial in the second half of 2026, to address critical global needs for expanded orthopoxvirus vaccine supply and biodefense preparedness. In oncology, GeoVax is developing Gedeptin®, a gene-directed enzyme prodrug therapy (GDEPT) designed to enhance immune checkpoint inhibitor activity. Gedeptin has completed a multicenter Phase 1/2 clinical trial in advanced head and neck cancer and is being advanced into combination strategies, including planned neoadjuvant and first-line settings. GeoVax maintains a global intellectual property portfolio supporting its infectious disease and oncology programs and continues to evaluate strategic partnerships and funding opportunities aligned with its development priorities. For more information, visit 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:
[email protected]
678-384-7220

Media Contact:
Jessica Starman
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