879P - VERSATILE-002: Survival with first-line treatment with PDS0101 therapeutic vaccine and pembrolizumab in HPV16-positive recurrent/metastatic head and neck squamous cell carcinoma (HNSCC)

Background

Immune checkpoint inhibitor (ICI) pembrolizumab with or without chemotherapy is first-line (1L) treatment for most patients with unresectable, recurrent or metastatic (R/M) HNSCC. PDS0101 (Versamune® HPV) is a novel, investigational HPV16-targeted therapeutic cancer vaccine that stimulates a potent, targeted T cell attack against HPV16-positive cancers.

Methods

We conducted a single-arm phase II study evaluating PDS0101 and pembrolizumab for 1L HPV16-positive R/M HNSCC. Subjects received pembrolizumab 200 mg IV Q3W with PDS0101 1 mL SC administered concurrently during Cycles 1, 2, 3, 4, and 12 and pembrolizumab monotherapy for all other Cycles up to Cycle 35 (approx. 2 years). The primary study endpoint was confirmed BOR per RECIST 1.1. Herein we report OS and update data on safety, ORR, and PFS in ICI naïve subjects.

Results

The study has completed enrollment. Ten subjects remain on treatment and 21 subjects are in long-term survival follow up. Demographics are previously reported; of note, 60.4% CPS 1-19 and 39.6% CPS ≥20. The median OS was 30 months (95% CI 18.4, NE) and the 12-month OS rate was 80%. Eighteen subjects (34%) had confirmed response by investigator assessment (4 CR and 14 PR). In the CPS≥20 cohort, 10/21 (48%) subjects had a confirmed response. The median PFS was 6.3 months (95% CI 3.1, 14.1). In the CPS≥20 cohort, median PFS was 14.1 months. Updated safety will be presented; no new safety signals emerged and the most common TRAEs remain injection site reactions, fatigue, headache, and pruritis with only 13% of subjects experiencing Grade ≥3 TRAEs. No subject had Grade 5 TRAE.

Conclusions

Enrollment is complete. Pembrolizumab plus PDS0101 shows excellent tolerability. Survival data are favorable compared to historic expectations, especially when PD-L1 levels of accrued subjects are considered. These results support further evaluation in a randomized phase III study.

Clinical trial identification

NCT04260126.

Editorial acknowledgement

Legal entity responsible for the study

PDS Biotechnology Corporation.

Funding

PDS Biotechnology Corporation.

Disclosure

J. Weiss: Financial Interests, Personal, Speaker, Consultant, Advisor: PDS Biotechnology. J. Kaczmar: Financial Interests, Personal, Advisory Board: PDS Biosciences, EMD serono; Financial Interests, Institutional, Local PI: EMD, PDS, Bicara, Merck, Replimmune; Financial Interests, Personal, Coordinating PI, research funding for IIT at MUSC: Signatera. K.J. Harrington: Financial Interests, Institutional, Steering Committee Member: GSK, AZ, MSD, Merck-Serono; Financial Interests, Institutional, Advisory Board: AZ, MSD, Merck Serono; Financial Interests, Institutional, Funding: AZ; Financial Interests, Institutional, Local PI: AZ, MSD; Financial Interests, Institutional, Invited Speaker: MSD, Merck-Serono; Financial Interests, Institutional, Research Funding: Merck-Serono; Financial Interests, Institutional, Speaker, Consultant, Advisor: Merck-Serono. R. Mehra: Financial Interests, Personal, Speaker, Consultant, Advisor: Coherus Biosciences, Janssen Oncology, Merck KGaA; Financial Interests, Institutional, Research Funding: AZ, Merck; Non-Financial Interests, Personal, Advisory Role: AZ. F. Worden: Financial Interests, Personal, Advisory Board: PDS Biotechnology. H. Kang: Financial Interests, Personal, Other, Consultant: PIN therapeutics, Hanmi Pharmaceuticals; Financial Interests, Personal, Other, Data safety monitoring board: MitoImmune; Financial Interests, Personal, Advisory Board: HLB group, LG Chem, Coherus; Financial Interests, Institutional, Coordinating PI: Elevar therapeutics; Financial Interests, Institutional, Local PI: Eli Lilly, PDS biotechnology, Ayala, Remix Therapeutics, Merus; Financial Interests, Institutional, Trial Chair: NeoImmune Tech; Non-Financial Interests, Member: American Society of Clinical Oncology, American Association for Cancer Research, International Thyroid Oncology Group, American Thyroid Association, Society of Immunotherapy of Cancer. C. Grant: Financial Interests, Personal, Advisory Board: Roche Pharmaceuticals, BMS; Financial Interests, Personal, Advisory Role: Roche Pharmaceuticals. S. Jones, D. Schaaf: Financial Interests, Personal, Stocks/Shares: PDS Biotechnology. K. Price: Non-Financial Interests, Institutional, Advisory Role: InSitu Biologics; Financial Interests, Institutional, Speaker, Consultant, Advisor: PDS Biotechnology. All other authors have declared no conflicts of interest.