ERBB2 and breast cancer: This is a multicenter, open label, phase 1/2 basket trial to evaluate the efficacy and safety of olaparib (PARPi) in combination with durvalumab (anti-PD-L1 mAb) in 264 patients with advanced solid tumors, which include metastatic and HER2-negative breast cancer containing germline BRCA mutation (gBRCAm), relapsed ovarian cancer with gBRCAm, relapsed small cell lung cancer (SCLC), and gastric cancer (initial stage cohorts).