Multi-Antigen COVID-19 Vaccine Candidate Outperforms mRNA Comparator; Enrollment Now Limited to GEO-CM04S1 Arm

ATLANTA, GA - September 15, 2025 (NEWMEDIAWIRE) - GeoVax Labs, Inc. (Nasdaq: GOVX), a clinical-stage biotechnology company developing multi-antigen vaccines and immunotherapies for infectious diseases and cancer, today showcased positive interim results for its lead COVID-19 vaccine candidate, GEO-CM04S1 at the XXI International Workshop on Chronic Lymphocytic Leukemia (iwCLL 2025) in Krakow, Poland.

The presentation by Alexey V. Danilov, MD, PhD, Professor, Department of Hematology and Transplantation at City of Hope, detailed data from an ongoing randomized Phase 2 trial (NCT05672355) comparing GEO-CM04S1 to a standard-of-care mRNA vaccine in patients with chronic lymphocytic leukemia (CLL).

Key Takeaways

• Differentiated Performance: The proportion of CLL patients receiving GEO-CM04S1 that achieved the study’s primary immune endpoint met the statistical requirement to continue enrollment, while those in the mRNA COVID-19 vaccine arm did not.
• Enrollment Shifted to GEO-CM04S1: Following interim analysis and following the recommendation of the Data Safety Monitoring Board, further enrollment is proceeding exclusively in the GEO-CM04S1 arm.
• Durable Market Potential: CLL patients represent a high-need, underserved market where first-generation COVID-19 vaccines are often inadequate.
• Favorable Safety Profile: Both vaccines were well tolerated, with no grade greater than or equal to 3 adverse events reported.

“These data reinforce the value proposition of our multi-antigen MVA platform,” said David Dodd, Chairman & CEO of GeoVax. “Immunocompromised patients, including those with CLL, have not been adequately protected by current vaccines. GEO-CM04S1 is demonstrating the ability to overcome this gap, representing not only a clinical breakthrough but also a compelling commercial opportunity.”

About GEO-CM04S1

GEO-CM04S1 is a next-generation COVID-19 vaccine built on a Modified Vaccinia Ankara (MVA) vector. Unlike first-generation vaccines, GEO-CM04S1 encodes both the Spike (S) and Nucleocapsid (N) proteins of SARS-CoV-2 to drive broad, cross-variant, and durable immune protection. The vaccine is currently in three Phase 2 clinical trials:

1. As a primary vaccine for immunocompromised patients with blood cancers or post-transplant status,
2. As a booster in CLL patients, and
3. As a more robust COVID-19 booster in previously mRNA-vaccinated healthy adults.

Strategic Opportunity

With millions of immunocompromised patients worldwide, including those with CLL and other hematologic malignancies, GEO-CM04S1 addresses a significant unmet medical and commercial need. The vaccine’s ability to induce nucleocapsid-specific responses sets it apart from existing single-antigen mRNA products, positioning GeoVax to lead in a multi-billion-dollar market segment where durable protection remains elusive.

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

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