Increasing number of ovarian cancer patients are receiving PARP inhibitor as maintenance or salvage therapy. Predictive factors to PARP inhibitor other than BRCA mutation or HRD status as well as specific resistance mechanism are unknown. Thus, the objective of this study was to prospectively collect serial blood samples in ovarian cancer patients with germline BRCA mutation who receive PARP inhibitor. We investigated circulating tumor DNA (ctDNA) before patients are started on PARP inhibitor and every 3 months thereafter until progression on PARP inhibitor. Through assessment of the changes in ctDNA mutational landscape, we aimed to investigate resistance mechanism to PARP inhibitor including BRCA reversion mutation.

Inclusion Criteria:

1. Pathological diagnosis of epithelial ovarian cancer,
2. Presence of germline or somatic BRCA mutation,
3. Patients receiving chemotherapy after primary debulking surgery or interval debulking surgery or patients who are planned to receive chemotherapy after recurrence on first line treatment,
4. Patients with platinum sensitive recurrence (recurrence after 6 months or longer after 1st line treatment) who are planned to receive PARP inhibitor following response to 2nd line chemotherapy.
5. Patients who recurred after 3rd or more lines of chemotherapy and are planned to receive PARP inhibitor.

Exclusion Criteria:

1. Patients who refuse to participate,
2. Patients having difficulty understanding the protocol due to language barrier

Ovarian cancer patients with germline BRCA mutation who receive PARP inhibitor