PDS Biotechnology Corporation announced that the Company achieved the threshold for efficacy as per investigator assessment in Stage 2 of the VERSATILE-002 (NCT04260126) Phase 2 clinical trial investigating PDS0101 in combination with Merck's anti-PD-1 therapy, KEYTRUDA® (pembrolizumab), for the treatment of unresectable, recurrent or metastatic human papillomavirus (HPV)16-positive head and neck cancer. The achievement of full recruitment of 54 patients in the ICI naïve arm was announced in May 2023. The threshold for efficacy, as defined in the clinical protocol, was achieved when 14 out of the 54 immune checkpoint inhibitor (ICI) naïve patients enrolled achieved a confirmed objective response.

Additional patients in the trial have yet to undergo imaging evaluation. Per RECIST 1.1, the standard to classify oncologic imaging outcomes in clinical trials, patients are considered to have achieved an objective response when imaging studies document tumor shrinkage of 30% or more. In VERSATILE-002, the primary endpoint requires two consecutive scans 9 to 12 weeks apart, rather than one, to be considered a confirmed objective response.

Confirmation with two consecutive scans is not required to achieve an objective response in every clinical trial per RECIST 1.1. At the recent 2023 American Society of Clinical Oncology (ASCO) Annual Meeting, company presented data showing 9 confirmed responses among 34 evaluable patients. Median progression free survival (PFS) of 10.4 months was also presented at the 2023 ASCO Annual Meeting along with a 12-month overall survival (OS) rate of 87.1% for patients with a CPS>1. Additional patients have been assessed since data was presented at the 2023 ASCO Annual Meeting. With these additional data, a total of 14 patients have now achieved a confirmed response to date.

The achievement of this endpoint suggests an additive effect of PDS0101 over published results with ICI monotherapy and is based on statistical calculations using the appropriate power and alpha. The primary endpoint in the VERSATILE-002 study is the best overall response (BOR) of confirmed complete response (CR) or confirmed partial response (PR) per RECIST 1.1. The key secondary endpoints are progression free survival (PFS), OS at 12 and 24 months, safety, and tolerability. The study utilizes a Simon's 2-stage optimum design.

DS Biotech plans to initiate the VERSATILE-003 as a result of the successful completion of an End-of-Phase 2 meeting in the third quarter of 2022 with the FDA, during which PDS Biotech received guidance on key elements of the Phase 3 program that will support the submission of a Biologics License Application (BLA). The planned primary endpoints for VERSATILE-003 are OS and PFS. In preparation for the VERSATILE-003 trial, PDS Biotech plans to submit an amended Investigational New Drug (IND) application to the FDA in the third quarter of 2023.