Study of SBRT/Olaparib Followed by Pembrolizumab/Olaparib in Gastric Cancers

This study is an open-label, phase II study with a safety lead-in to assess the response rate of induction olaparib and stereotactic beam radiotherapy (SBRT) followed by combination olaparib/pembrolizumab in patients with metastatic gastric and GEJ cancers after at least one of therapy. The secondary endpoint is combined therapy in tumors with evidence of both homologous recombination deficiency (by germline or somatic Next-generation DNA sequencing \[NGS\]), as well as homologous recombination proficiency. Exploratory endpoints will assess the impact of homologous recombination deficiency and proficiency on response to radiation, PARP inhibition and PD-1 blockade.