GeoVax Labs, Inc. announced that it has met the enrollment target for its Phase 2 clinical trial evaluating GEO-CM04S1 as a booster for healthy patients who have previously received the Pfizer or Moderna mRNA vaccine. The study is designed to evaluate the safety profile and immunogenicity of two GEO-CM04S1 dose levels administered as a COVID-19 vaccine booster among healthy individuals previously vaccinated with one of the FDA approved SARS-CoV-2 mRNA vaccines. The immunological responses measured throughout the study will include both the level of neutralizing antibodies against SARS-CoV-2 variants of concern and specific T cell responses.

GEO-CM04S1 is a next-generation COVID-19 vaccine based on GeoVax?s MVA viral vector platform, which supports the presentation of multiple vaccine antigens to the immune system in a single dose. GEO-CM04S1 encodes for both the spike (S) and nucleocapsid (N) antigens of SARS-CoV-2 and is specifically designed to induce both antibody and T cell responses to those parts of the virus less likely to mutate over time. The more broadly functional engagement of the immune system is designed to protect against severe disease caused by continually emerging variants of COVID-19.

Vaccines of this format should not require frequent and repeated modification or updating. In addition to the booster vaccine trial for which patient enrollment was just completed, GEO-CM04S1 is being evaluated in two other Phase 2 clinical trials: As a primary vaccine in immunocompromised patients (with hematologic cancers receiving cell transplants or CAR-T therapy). A recent presentation of unpublished data from the open-label portion of the trial indicates that GEO-CM04S1 is highly immunogenic in these patients, inducing both antibody responses, including neutralizing antibodies, and T cell responses.

These data support the progression of the Phase 2 clinical study, which includes a direct comparison to currently approved mRNA vaccines. As a booster vaccine in immunocompromised patients with chronic lymphocytic leukemia (CLL), a recognized high-risk group for whom current mRNA vaccines and monoclonal antibody (MAb) therapies appear inadequate relative to providing protective immunity.