BAP1 is an ubiquitin ligase that is critical in helping to regulate the cell cycle, cellular differentiation, and cell death. This protein is also intimately involved with DNA double-strand break repair. Germline mutations in the BAP1 gene are associated with a hereditary cancer syndrome that increases the risk of uveal melanoma, mesothelioma and renal cell carcinoma. PARP is another protein that is crucial in DNA repair and enables continued cell replication and survival. It is hypothesized that PARP inhibition with niraparib will result in significant cytoreduction in patient tumors with mutations in BAP1 and other components of the DNA damage response pathway through synthetic lethality. Synthetic lethality is the inhibition of a gene that a cell relies on to compensate for the loss of another gene, resulting in the cell's demise.