This is a phase II open label single arm study of OBP-301 in combination with pembrolizumab and SBRT in advanced HNSCC which is either recurrent and inoperable, or progressing after prior radiation with curative-intent for advanced disease (adjuvant or definitive with or without chemotherapy or cetuximab).~The efficacy of pembrolizumab monotherapy is modest in second or third line of treatment of advanced head and neck cancer (~response rate 16-22%). SBRT reirradiation in patients that received prior surgery and chemoradiation for advanced disease is associated with a response rate (RR) of approximately 60% and approximately 50% 1-year survival. Recently, the results of the Keynote-048 study were published. The projected 1-year survival in the immunotherapy arms with pembrolizumab alone or pembrolizumab and chemotherapy was approximately 57%. So, at present, the benchmark RR for patients with head and neck squamous cell carcinoma with inoperable, recurrent or progressive disease treated with SBRT is approximately 60% and the 1 year survival for patients with head and neck squamous cell carcinoma (HNSCC) with inoperable, recurrent or progressive disease using the most effective contemporary treatments including immunotherapy is approximately 50-57%. Trying to improve the results of the current standard of care, this study will examine the effects of oncolytic virus, OBP-301, administered in addition to pembrolizumab and SBRT in this patient population. The goal of using this triple therapeutic combination is to enhance the chances of cure of the patients.~A total of 36 patients will be enrolled into a two-stage parallel cohort design: In the first stage, 12 patients will be enrolled.~All patients will receive intratumoral injection(s) with OBP-301. If tolerated and no progression is observed, up to twelve injections may be given in each patient.~If the targeted injected lesion(s) disappear, another lesion can be injected at the Investigator's discretion.~A minimum additional 3 doses of concurrent OBP-301 and pembrolizumab will be given if no toxicity, technical impediment to injection or progression is seen.~A maximum total of up to 9 doses of concurrent OBP-301 and pembrolizumab will be given.~Pembrolizumab alone will be continued after day 183 for a total treatment time up to 1 year.
The purpose of this study is to test the effects, of the research study drug Telomelysin (OBP-301) in combination with pembrolizumab in subjects with inoperable, recurrent, or progressive squamous cell carcinoma of the head and neck. Telomelysin is an investigational treatment, while pembrolizumab and SBRT are approved standard treatments. The combination of these three treatments is also considered investigational.