PDS Biotech has reported final phase 2 data on PDS0101 in the tough-to-treat head and neck cancer setting, linking a combination of the immunotherapy and Keytruda to median overall survival (OS) of 39.3 months.
The data come from Versatile-002, a phase 2 trial that enrolled 53 people with HPV16-positive first-line recurrent and/or metastatic head and neck squamous cell cancer (HNSCC). Participants received a regimen that combined PDS0101, a HPV16-targeted therapeutic cancer vaccine, with Merck & Co.’s PD-1 blockbuster Keytruda.
PDS reported a median OS of 39.3 months in patients with a combined positive score (CPS) of one or greater. CPS is a measure of PD-L1 expression. Keytruda is approved (PDF) for first-line monotherapy use in metastatic or unresectable, recurrent HNSCC in patients with a CPS of one or greater. The lower limit of the median OS estimate was 23.9 months.
The biotech compared its median OS to the 17.9 months seen in another Keytruda study. PDS said 17.9 months of OS is the best published result with standard of care Keytruda, either as a monotherapy or in combination with chemotherapy.
PDS previously reported (PDF) a median OS of 30 months from Versatile-002 for the 53 patients with a CPS of one or higher. In that earlier update, PDS reported a median OS of 39.3 months in 21 patients with a CPS of 20 or higher, indicating they had more expression of PD-L1.
The biotech started a phase 3 trial of PDS0101 and Keytruda in HNSCC in May. The registrational trial is designed to enroll 351 people to compare the combination to single-agent Keytruda. ClinicalTrials.gov lists the trial’s completion date as February 2029. PDS told investors earlier this month that it will be able to fund its operating expenses and capital expenditure requirements into the fourth quarter of 2025.
The race for the HNSCC market has thinned in recent years. Eisai and Merck stopped a phase 3 trial over lackluster OS data in 2023, but PDS still faces potential competition from companies including BioNTech. The German biotech is testing its cancer vaccine BNT113 in combination with Keytruda in a phase 2/3 trial.