This is a phase II study of OBP-301 with pembrolizumab in advanced gastric and gastroesophageal junction adenocarcinoma that has progressed on at least 2 lines of prior therapy for advanced disease. Pembrolizumab has recently received FDA approval for PD-L1 positive gastric and GEJ adenocarcinoma based on the Keynote-059 study. The efficacy of pembrolizumab monotherapy is modest in PD-L1 positive patients (defined as a combined positive score, CPS, of > 1), with only a ~15% overall response rate. This study will examine the addition of the oncolytic virus, OBP-301, administered prior to pembrolizumab in this patient population. Patients will be enrolled in a two-stage design, with 18 patients in the first stage. All patients will receive OBP-301 at 2x1012 viral particles (VP)/ tumor injection administered every two weeks x 4 injections as well as standard dose pembrolizumab 200 mg IV every 3 weeks. The tumor will be injected with OBP-301 four times (d1, d15, d29, d43). The preference is to inject the primary tumor endoscopically. Metastatic lesions may be injected on a case-by-case basis after discussion with the PI (Shah). All patients treated with OBP-301 will be eligible for the safety cohort.~Primary Endpoints:~To examine the efficacy of OBP-301 with pembrolizumab in PD-L1 positive advanced gastric and gastroesophageal junction adenocarcinoma in the 3rd or 4th line setting, as assessed by the RECIST response rate.~To examine the safety of multiple OBP-301 intratumoral injections in combination with pembrolizumab in advanced gastroesophageal adenocarcinoma.~Secondary Endpoint:~• To examine other measures of efficacy of the combination of OBP-301 with pembrolizumab in advanced gastric and esophageal adenocarcinoma including the disease control rate, duration of response, overall survival and progression free survival.
This is a phase II study of OBP-301 with pembrolizumab in advanced gastric and gastroesophageal junction adenocarcinoma that has progressed on at least 2 lines of prior therapy for advanced disease.