Introduction/Background MAP kinase pathway alterations are prevalent in low grade serous ovarian cancer (LGSOC) in up to 60% of patients, of them, minority harbor BRAF V600E mutation. While MILO-ENGOT ov11 study showed 13% response to Binimetinib (a MEK inhibitor), irrespective of mutation status, the value of BRAF and MEK inhibition in BRAF mutant patients was not evaluated. Herein we report the results of 5 patients treated with Dabrafenib and Trametinib (D+T) for non-resectable LGSOC.

Methodology We collected data from 5 patients who received D+T combination as compassionate use for BRAF V600E mutant LGSOC. All patients signed the Israeli informed consent for the use of off-label medications. Data on disease stage, prior lines of therapy, best response per RECIST, duration of response (DOR), survival and safety were collected.

Results 5 patients were treated with the combination of D+T. The median age was 53.8 years. The stage of the disease varied from IIIC-IVB (2/3). Median prior systemic treatment lines was 2 (range 0–5). Overall 4 of 5 patients (80%) had documented response. 2 patients achieved CR, and 2 patients had PR as best response. 1 patient was not evaluated due to early clinical deterioration. PFS was 18 months for the first patient, other 3 have ongoing responses at 18, 5 and 5 months. All patients had major relief of symptoms. 1 patient had 2 re-inductions of treatment following subsequent chemotherapy with 6 months PFS in each re-induction. The most frequent side effects were fatigue G1 (5/5) and pyrexia (4/5). None required permanent discontinuation. 3 patients are still receiving treatment.

Conclusion Targeting BRAF V600E mutation with combined BRAF and MEK inhibition in LGSOC yields high response rate with durable and meaningful improved disease control. These cases should emphasize the importance of performing the BRAF V600E mutation test for all patients with LGSOC.