Abstract 569P
Background
Single agent immune checkpoint inhibitors are largely ineffective in treating recurrent ovarian cancer (OC). In a recently completed phase 2 clinical trial at our institute (NCT02853318), we combined pembrolizumab with anti-VEGF bevacizumab and oral metronomic cyclophosphamide in patients with recurrent ovarian cancer. Our phase 2 trial had a median progression free survival (PFS) of 10.0 months and 25% of the recurrent OC patients had a PFS > 12 months with excellent quality of life. Based on the results of this trial, our center has been using this regimen off label in patients with recurrent gynecologic malignancies, given the limited efficacy of traditional second line chemotherapies in this patient population.
Methods
This was a retrospective, single center study in 55 patients, who received pembrolizumab 200mg IV in combination with bevacizumab 15mg/kg IV every 3 weeks and cyclophosphamide 50mg by mouth daily on a 21-day cycle until disease progression, or unacceptable toxicity. The primary endpoint of this study is efficacy of the regimen, calculated by objective response rate (ORR). Data was obtained via electronic health records from 2016 through 2021. Subjects were identified based on inquiry of all OC patients who received this regimen outside of the phase 2 clinical trial.
Results
The 55 OC patients included in this analysis had a mean (SD) age of 63.4 (9.8) years. The cohort was heavily pretreated, the mean number of prior chemotherapies received was 3.5 (range 1-9). 54% of the patients had progressed on a prior regimen containing bevacizumab. The ORR in this cohort of patients was 42% (23/55), with 6% (3/55) having complete response, 36% (20/55) having partial response, and 49% (27/55) having stable disease.
Conclusions
In this retrospective study, the combination of pembrolizumab, bevacizumab, and oral cyclophosphamide demonstrated minimal toxicity with a clinical benefit in 90% of the patients and durable treatment responses ( > 9 cycles) in 31% of patients. This combination regimen may be beneficial as future treatment for recurrent ovarian cancer.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.