TESARO, Inc. is an oncology-focused biopharmaceutical company. The Company operates through the business of developing and commercializing of oncology-focused therapeutics segment. It is developing oncology-related product candidates, including rolapitant, niraparib and the product candidates under its immuno-oncology platform. Rolapitant is a potent and long-acting neurokinin-1 receptor antagonist for the prevention of chemotherapy induced nausea and vomiting. Niraparib is an orally active and potent poly (adenosine diphosphate (ADP)-ribose) polymerase inhibitor. It has various ongoing clinical trials evaluating niraparib for the treatment of ovarian or breast cancers. It has initiated a Phase I, dose escalation study for its first immuno-oncology antibody, TSR-042, which targets Programmed cell death protein 1. It has commenced pre-clinical research for its antibody candidate targeting Lymphocyte-activation gene-3 andTSR-033. It has commenced a Phase I clinical trial of TSR-042.