Geneos Therapeutics has published positive results from its Phase I/II GT-30 clinical trial of GNOS-PV02, a personalised neoantigen vaccine, in combination with pembrolizumab for advanced hepatocellular carcinoma (HCC).

GNOS-PV02 is a DNA plasmid-encoded personalised therapeutic cancer vaccine (PTCV) formulated with DNA plasmid-encoded IL-12 (a cytokine adjuvant), and pembrolizumab.

The multicentre, single-arm, open-label trial evaluated the safety, immunogenicity, and efficacy of the vaccine in 36 second-line (2L) patients priorly treated with a multi-tyrosine kinase inhibitor.

According to the findings, the study met its primary endpoints of safety and immunogenicity, and the secondary endpoint of efficacy, as measured by the observed response rate (ORR).

Notably, PTCV-related adverse events were limited to Grades 1 and 2 without any dose-limiting toxicities or adverse events lower than Grade 3 reported.

Reactions at the injection site were observed to be the most common adverse events, occurring in 41.6% of subjects in the trial.

This favourable safety profile is particularly significant in the context of immuno-oncology combination regimens, which often lead to increased toxicity. The addition of a PTCV to a PD-1 inhibitor did not result in any significant decrease in patient safety and tolerability.

The ORR for the GT-30 trial is currently at 30.6%, including three complete responses and eight partial responses.

Geneos CEO and president Niranjan Sardesai said: “Despite the small size of this study, our results are important for the advancement of the field.

“We have not only met endpoints for safety, immunogenicity, and clinical efficacy based on ORR in this difficult-to-treat setting, but our mechanism of action data trace and confirm every step, from vaccination to tumour reduction, required to explain the immunological basis for the observed clinical responses.”