GeoVax's Gedeptin Shows Promise to Boost Checkpoint Inhibitors in Resistant Tumors

GeoVax Labs, Inc. (Nasdaq: GOVX), a clinical-stage biotechnology company, announced a groundbreaking publication in the Journal of Clinical Investigation Insight supporting its Gedeptin® immuno-oncology platform. The study, titled “Broadening Activity of Checkpoint Blockade Agents by Intratumoral Nucleoside Cleavage,” validates the potential of intratumoral Gene Directed Enzyme Prodrug Therapy (GDEPT) to enhance immune checkpoint inhibitor responses and activate systemic anti-tumor immunity. The research, conducted on triple-negative breast cancer (TNBC-EMT6) cells resistant to conventional treatments, demonstrates that E. coli PNP/F-araA—the therapeutic concept behind Gedeptin—can kill treated tumors and boost checkpoint inhibitor activity against both treated and untreated tumors.

In vitro studies showed that E. coli PNP/F-araA treatment triggered a signaling cascade linked to immune sensitization. In vivo, tumors expressing E. coli PNP were completely eradicated in mice treated with F-araAMP, a prodrug of F-araA. Crucially, when subcurative doses were combined with immune checkpoint inhibitors, significant tumor reduction and complete regressions occurred. Remarkably, immune checkpoint blockade also enhanced anti-tumor effects on distant, untreated tumors after a single cycle of localized therapy, suggesting a systemic immune response. These findings indicate that Gedeptin could act as a “force multiplier” for checkpoint inhibitors, disrupting immunosuppressive tumor microenvironments and broadening responses beyond directly treated lesions.

GeoVax’s Gedeptin platform uses a non-replicating adenoviral vector to deliver purine nucleoside phosphorylase (PNP), which converts fludarabine into a potent cytotoxic compound within tumors. This localized activation, combined with a strong bystander killing effect and immune-sensitizing properties, positions Gedeptin as a versatile therapy for solid tumors resistant to checkpoint inhibitors. The company plans to advance clinical development with pembrolizumab-based regimens. For more information, visit www.geovax.com. This news was distributed via NEWMEDIAWIRE.