Use of Nivolumab As Salvage Therapy in Heavily Pretreated Patients with Gynecologic Malignancies.

5593 Background: There are limited effective treatments for gynecologic cancer patients who have been previously treated with multiple lines of chemotherapy. Immune checkpoint inhibitor (ICI) therapy has demonstrated significant activity in certain cancers but has been inconclusive in most gynecologic malignancies. The objective of this study was to determine the impact of salvage ICI therapy in heavily pretreated gynecologic oncology patients. Methods: An IRB approved retrospective study was performed of women with gynecologic cancer treated with nivolumab on a compassionate use program between October 2015 and January 2018. Patient demographics, disease characteristics, pathology and treatment history were collected. Survival probabilities were calculated. Results: Twenty-eight women were identified. Median age at start of treatment was 63 years with a median of 4 prior lines of chemotherapy. Median ECOG status was 2. Disease site was evenly distributed among uterus, ovary and cervix. 67.9% of patients completed 3 or more cycles of treatment. Median PFS of all patients was only 2.6 months however when comparing patients who received 2-3 cycles (n = 13) with those who received 4 or more (n = 9), median PFS was statistically significant 2.4 months vs 6.4 months (p = 0.0005). When looking at treatment response, 7 patients had partial response/stable disease after 3 cycles (25%). Median PFS of the 7 “responders” was 6.6 months vs 2.5 months of the non-responders (p < 0.001). Only 1 of 9 patients with uterine cancer had a disease response and that patient’s tumor was MSI high. Five patients had low grade serous ovarian cancer. Four of them had a treatment response with a median PFS of 6.1 months (range 3.8 – 25 months). Adverse events were experienced by 68% of patients; most commonly being fatigue (46.4%), arthralgia (25%), and anemia (21.4%). Only 1 patient experienced a grade 3-4 event (a diffuse maculopapular rash). Conclusions: In patients with heavily pretreated gynecologic malignancies with suboptimal performance status, immune checkpoint inhibitor therapy may prolong survival without significant toxicity. Also, there may be a role for ICI in patients with historically chemo resistant low grade serous ovarian cancers.