Excellent Response to Olaparib in a Patient with Metastatic Pancreatic Adenocarcinoma with Germline BRCA1 Mutation after Progression on FOLFIRINOX: Case Report and Literature Review

Metastatic pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis. Until recently, cytotoxic chemotherapy was the only treatment option. Currently, there are subgroups of patients with PDAC either with somatic or germline mutations who are candidates for targeted agents. Germline mutations in the BRCA1 and BRCA2 genes promote the incapacity of tumor cells to recover from DNA-accumulated damage caused by cytotoxic drugs, like platinum agents, and, most recently, through a diverse process by poly(adenosine diphosphate-ribose) polymerase inhibitor (PARPi). A 59-year-old female who was treated for a triple negative breast cancer 8 years ago with surgery, adjuvant chemotherapy and radiotherapy, presented with increasing back pain. Investigation revealed multiple liver nodules and a large mass in the head of the pancreas. Biopsy confirmed PDAC. She received 13 cycles of FOLFIRINOX, achieving partial response both in the liver and pancreatic lesion, with resolution of symptoms. Due to increasing neuropathy, chemotherapy was stopped, and the patient was followed. Sixteen months later, her CA19-9 levels increased. Given limiting neuropathy, the patient was restarted on FOLFIRI only. After 8 cycles, there was disease progression plus uncontrolled back pain. A mutational test was requested and confirmed a BRCA1 germline mutation. The patient was started on olaparib. After 3 cycles, images showed a significant response and after 6 cycles, it remained stable, with persistent fall in CA19-9 levels. She is currently on treatment, with ongoing response. In conclusion, patients with metastatic PDAC and BRCA mutation may benefit from PARPi even after progression on chemotherapy. We hypothesize that olaparib works even in the setting of disease progression and not solely as a maintenance therapy following platinum-based therapy. Randomized trials are needed investigating the role of olaparib following disease progression in PDAC.