Testing the Combination of DS-8201a and Olaparib in HER2-Expressing Cancers With Expansion in Patients With Platinum Resistant Ovarian Cancer

This phase I trial identifies the side effects and best dose of DS-8201a and olaparib in treating patients with HER2-expressing cancers that have spread to other places in the body or cannot be removed by surgery or ovarian cancer that remains despite treatment with a platinum treatment (platinum resistant). Olaparib is a drug that blocks an enzyme involved in many cell functions, including the repair of deoxyribonucleic acid (DNA) damage. Blocking this enzyme may help keep tumor cells from repairing their damaged DNA, causing them to die. DS-8201a is an antibody-drug conjugate. This agent has two components: an antibody component and a chemotherapy component. The antibody component is attached to the chemotherapy molecules. Upon administration of DS-8201a, the antibody targets and binds to tumor cells that have abundant HER2 (human-epidermal growth factor receptor 2), which is a protein on the surface of some tumor cells. The chemotherapy then enters the cells and blocks DNA replication in the tumor cells with abundant HER2, causing them to die. Giving DS-8201a and olaparib may shrink or stabilize the cancer.