EQS-News: GeoVax Announces JCO Oncology Advances Publication Highlighting Favorable Safety and Evidence of Disease Stability of Gedeptin(R) in Recurrent Head & Neck Cancer

Phase 1/2 Trial Confirms Safety With Repeated Dosing Supporting Further Development in Early-stage Disease and Combination Treatment Settings

ATLANTA, GA - December 8, 2025 (NEWMEDIAWIRE) - GeoVax Labs, Inc. (Nasdaq: GOVX), a clinical-stage biotechnology company developing novel immunotherapies and vaccines for solid tumor cancers and infectious diseases, today announced the publication of a peer-reviewed article in JCO Oncology Advances, the American Society of Clinical Oncology’s (ASCO) open-access journal.

The manuscript, titled “A Phase 1/2 Study of Intratumoral Ad/PNP (Gedeptin) with Fludarabine Phosphate in Subjects with Recurrent Head and Neck Cancer”, reports findings from a multi-center clinical trial evaluating repeated cycles of Gedeptin®, a gene-directed enzyme prodrug therapy (GDEPT), administered via intratumoral injection followed by systemic fludarabine.

Study Overview: Evaluating Repeated Dosing in a Highly Refractory Population

The Phase 1/2 trial enrolled patients with recurrent head and neck cancers who had exhausted all standard treatment options and had undergone a median of four prior lines of systemic therapy. Patients received therapy on a 28 day schedule, each consisting of intratumoral Gedeptin injections followed by intravenous fludarabine.

Key results from the publication include:

• Acceptable safety profile with no new safety signals: Serious adverse events were uncommon and generally unrelated to treatment. No deaths were attributed to study therapy.
• Clinical evidence of disease stability: Three of eight patients (37.5%) in this cohort of patients with end-stage disease achieved stable disease.
• Successful tumor transduction and PNP transgene expression: Tumor biopsies confirmed uptake and expression of the therapeutic E. coli PNP transgene in all evaluable patients, supporting the mechanistic foundation of the Gedeptin platform.

Study results suggest that earlier intervention, higher vector dosing, improved tumor transduction, or combination therapy (e.g., with immune checkpoint inhibitors) may further increase efficacy. Preclinical findings cited in the manuscript show that Gedeptin-mediated tumor destruction may sensitize tumors to checkpoint inhibitors, offering a promising path forward.

J. Marc Pipas, MD, Executive Medical Director, Oncology of GeoVax, stated: “This publication reinforces the strong scientific rationale underpinning the Gedeptin platform. Even in a highly refractory patient population with extensive prior treatment, repeated intratumoral dosing of Gedeptin demonstrated a favorable safety profile and evidence of disease stability. Importantly, correlative analyses confirmed robust tumor transduction and PNP expression, a critical mechanistic milestone for gene-directed enzyme prodrug therapy.”

Kelly T. McKee, MD, MPH, Chief Medical Officer of GeoVax, added: “These results support the continued development of Gedeptin in settings where tumor burden is lower, patients are less heavily pretreated, or where combination strategies, particularly with immune checkpoint inhibitors, may amplify therapeutic benefit. This aligns with our strategy to advance Gedeptin into neoadjuvant studies for surgically resectable recurrent head and neck cancers.”

David Dodd, Chairman & CEO of GeoVax, stated: “The publication in the ASCO journal underscores both the scientific significance of this trial and the need for new approaches to treat recurrent head and neck cancers. Gedeptin’s targeted mechanism, combined with its repeat-dosing feasibility, offers a promising therapeutic option for patients. We look forward to expanding development into earlier disease settings and into rational combination regimens.”

About the Gedeptin® Platform

Gedeptin is a non-replicating adenoviral vector delivering the E. coli purine nucleoside phosphorylase (PNP) gene directly into tumor tissue. Following intratumoral injection, patients receive systemic fludarabine, which is converted in PNP-expressing tumor cells into a potent cytotoxic metabolite (2-fluoroadenine, F-Ade).

Key characteristics include:

• Tumor-agnostic mechanism of action, driven by localized intratumoral activation of fludarabine into the potent cytotoxin F-Ade, enabling activity independent of tumor histology or proliferation rate.
• Strong bystander effect, in which the activated F-Ade diffuses to neighboring cancer cells - allowing Gedeptin to kill tumor cells even when only a small fraction is directly transduced.
• Immune-sensitizing properties that enhance tumor antigen visibility and may improve responses to immune checkpoint inhibitors.
• Favorable safety profile, demonstrated across early Phase 1 and Phase 1/2 studies and supported by consistent tolerability in heavily pretreated solid tumor patients.

Gedeptin is now progressing toward combination-therapy in a neoadjuvant clinical program. Building on robust preclinical data showing that Gedeptin enhances tumor sensitivity to immune checkpoint blockade, GeoVax is advancing plans to evaluate Gedeptin with agents such as pembrolizumab aiming to strengthen antitumor immune activation.

About GeoVax

GeoVax Labs, Inc. is a clinical-stage biotechnology company developing novel vaccines against infectious diseases and therapies for solid tumors. 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 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 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

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