This phase I/II trial studies how well pembrolizumab and carboplatin work in treating
patients with ovarian, fallopian tube, or primary peritoneal cancer that has come back or has
not responded to previous treatment. Monoclonal antibodies, such as pembrolizumab, may
interfere with the ability of tumor cells to grow and spread. Drugs used in chemotherapy,
such as carboplatin, work in different ways to stop the growth of tumor cells, either by
killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving
pembrolizumab and carboplatin may work better in treating patients with ovarian, fallopian
tube, or primary peritoneal cancer.