GeoVax to Advance Gedeptin(R) Into First-Line Therapy Neoadjuvant Combination Trial Following Landmark KEYNOTE-689 Results

Revised Phase 2 Strategy Targets Event-Free Survival in Primary Head and Neck Cancer through Checkpoint Inhibitor Combination

The revised strategy follows the landmark results of the KEYNOTE-689 Phase 3 trial, published in the New England Journal of Medicine on June 18, 2025, which demonstrated a significant improvement in event-free survival (EFS) with the addition of perioperative pembrolizumab in resectable, locally advanced HNSCC patients. These data represent the first validated use of PD-1 inhibition in curative-intent HNSCC and have catalyzed a major shift in treatment paradigms toward neoadjuvant immunotherapy.

GeoVax’s new Phase 2 trial (AdPNP-203) will evaluate the addition of intra-tumoral Gedeptin®, intravenous fludarabine, and pembrolizumab in patients 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 2026.

“The KEYNOTE-689 results support our view that neoadjuvant checkpoint inhibition can transform the treatment of head and neck cancer,” said Dr. Kelly McKee, Chief Medical Officer at GeoVax. “By integrating Gedeptin into this emerging standard, we hope to improve both local tumor clearance and event-free survival, especially for high-risk or PD-L1-low patients.”

“This is a strategic shift in our program,” added David Dodd, Chairman and CEO of GeoVax. “We believe Gedeptin’s localized cytotoxic mechanism, when combined with systemic checkpoint inhibition for first-line treatment, can meaningfully improve therapeutic outcomes in patients with resectable HNSCC.”

Rationale for Combination Strategy

As highlighted in the NEJM editorial, the benefit in KEYNOTE-689 may be driven primarily by the neoadjuvant component of immunotherapy. However, many patients still experience local or distant relapse, underscoring the need for intensified strategies in the perioperative window. Gedeptin, with its dual cytotoxic and immune-priming mechanism, may serve as an ideal partner to checkpoint inhibitors by converting “cold” tumors into “hot” immunogenic targets.

About Gedeptin®

Gedeptin is a gene-directed enzyme prodrug therapy (GDEPT) using a non-replicating adenoviral vector encoding purine nucleoside phosphorylase (PNP). Once delivered directly into tumors and followed by fludarabine, PNP enzymatically converts the prodrug into a cytotoxic compound, selectively targeting tumor cells while sparing healthy tissue. This localized approach aims to reduce toxicity, enhance immune visibility, and enable immune checkpoint synergy.

Gedeptin has received Orphan Drug Designation for oral and pharyngeal cancers and is backed by a robust intellectual property portfolio. GeoVax’s ongoing innovation in immune-sensitizing therapies supports a broader strategy to complement checkpoint inhibitors and overcome tumor immune resistance across solid tumor types.

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 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

Investor Relations Contact:
geovax@precisionaq.com
212-698-8696

Media Contact:
Jessica Starman
media@geovax.com

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