A Study of Niraparib in People With Soft Tissue Sarcoma Who Have Changes in Their Tumor DNA

The purpose of this study is to test whether the study drug, niraparib, is effective against unresectable and/or metastatic soft tissue sarcoma with DDR mutations. The researchers will also study whether niraparib is safe and causes few or mild side effects, and whether there are groups of DDR mutations in soft tissue sarcoma cells that respond better to treatment with niraparib.