PARP inhibitors have also shown promise in early trials, particularly in people with "BRCA" gene mutations, since the BRCA protein interacts with the PARP pathway. It is also being studied in recurrent ovarian cancer in general, where preliminary studies have shown longer PFS. Specifically, olaparib has shown greater survival compared to doxorubicin, though this treatment is still being investigated. It is not clear yet which biomarkers are predictive of responsiveness to PARP inhibitors. Rucaparib is another PARP inhibitor being researched in BRCA-positive and BRCA-negative recurrent advanced ovarian cancer. Niraparib is a PARP inhibitor being tested in BRCA-positive recurrent ovarian cancer.