Sustained response to vemurafenib in a low grade serous ovarian cancer with a BRAF V600E mutation

Low-grade serous ovarian adenocarcinomas (LGSOC) make up approximately 10 % of serous ovarian carcinomas. While rarely aggressive, this slow-growing tumor is well known to respond poorly to chemotherapy. Specific treatments for this ovarian subtype are lacking, with the same global approaches used for high grade cases being applied for LGSOC patients. LGSOCs have been reported to have a specific genetic profile, with notable implication of the MAPK pathway. This has opened up opportunities for novel therapeutic strategies, with in particular the use of targeted therapies. We report here the case of a heavily pretreated unresectable BRAF p.V600E-mutated LGSOC, which we treated vemurafenib, a BRAF inhibitor specific for V600E mutations. We saw impressive efficacy, with a long-term partial response along with CA125 reductions and symptom relief. Although this mutation is present in LGSOC at very a low incidence, we recommend routine testing for BRAF and other targetable mutations in this patient population, along with further evaluation in the increasingly popular basket trial approach.