On February 24, 2025 PDS Biotechnology Corporation (Nasdaq: PDSB) ("PDS Biotech" or the "Company"), a late-stage immunotherapy company focused on transforming how the immune system targets and kills cancers, reported the publication of circulating tumor DNA (ctDNA) results for its lead immunotherapy candidate, Versamune HPV, in Clinical Cancer Research, a journal of the American Association for Cancer Research (AACR) (Free AACR Whitepaper) (Press release, PDS Biotechnology, FEB 24, 2025, View Source [SID1234650478]).

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The trial demonstrated that Versamune HPV was associated with greater and earlier clearance of HPV16-positive cancer cells from the bloodstream in patients with locally advanced cervical cancer. Notably, the elimination of HPV16-positive ctDNA correlated with extended patient survival without cancer recurrence, reinforcing its potential to improve long-term outcomes. The data underscore the potential of Versamune HPV in HPV16-positive cancers as the Company prepares to initiate a Phase 3 clinical trial for Versamune HPV in HPV16-positive head and neck squamous cell carcinoma (HNSCC) in the first quarter of this year.

"These findings highlight the transformative potential of Versamune HPV in broadly treating various HPV16-associated cancers. Combining Versamune HPV with chemoradiation (CRT) was linked to rapid HPV16 ctDNA decline," said Frank Bedu-Addo, PhD, President and Chief Executive Officer of PDS Biotech. "We believe that such results showing a strong correlation between a biomarker such as ctDNA and survival may allow us to initiate discussions with the U.S. Food and Drug Administration regarding the potential for an accelerated regulatory pathway such as Breakthrough Therapy designation in cervical cancer. We also think this finding that links the reduction of ctDNA level with improved survival may apply to other HPV16-positive cancers like HNSCC. This endpoint is currently included within our VERSATILE-003 Phase 3 clinical trial."

A total of 66 patients with locally advanced cervical cancer were enrolled, with 49 receiving CRT and 17 receiving a combination of CRT and Versamune HPV. Patient blood was collected at baseline, weeks 1, 3, and 5 of CRT, and 3 to 4 months after CRT to measure HPV ctDNA. MRI was performed at baseline and before brachytherapy to determine tumor shrinkage.

Median follow-up was 23 months. At 3-4 months follow-up, 5/5 (100%) HPV16-positive patients receiving CRT + Versamune HPV had no detectable HPV16-positive ctDNA, whereas 3/6 (50%) of patients receiving only CRT had no detectable ctDNA.

HPV ctDNA clearance at 3-4 months correlated with better 2-year recurrence free survival (RFS) (92.9% vs. 30%, log-rank; P = 0.0067). The strongest predictor of RFS was HPV ctDNA clearance at 3-4 months follow-up, achieving a concordance index score of 0.83.

The 36-month overall survival (OS) and progression free survival rates were earlier reported to be 100% for the 8 patients in the trial who received 5 doses of Versamune HPV + CRT and an 84.4% 36-month OS rate for 17 patients who received at least 2 doses of Versamune HPV + CRT.