Objectives To describe the clinical activity of metronomic cyclophosphamide in a population of patients with recurrent ovarian cancer, and to identify predictors of clinical response.

Methods We retrospectively reviewed all patients treated at our institution with oral metronomic cyclophosphamide for relapsed ovarian cancer between January 2012 and December 2016. These were identified from electronic chemotherapy prescription records. The primary endpoint was response rate by combined Gynecologic Cancer InterGroup (GCIG) criteria. Data on patient demographics, previous therapies, platinum resistance, germline BRCA1/2 (gBRCA1/2) status, disease response by radiological or cancer antigen 125 (CA125) criteria alone, adverse events secondary to metronomic cyclophosphamide treatment, progression-free survival, and overall survival were also evaluated.

Results 50 out of 68 patients treated with oral metronomic cyclophosphamide were evaluable for disease response. By combination criteria (radiological plus CA125), complete response was 0%, partial response 32%, stable disease 16%, and progressive disease 52%. In the intention-to-treat population (n=68), progression-free survival and overall survival were 2.6 months and 6 months, respectively. Having a gBRCA1/2 mutation reduced the risk of disease progression by radiological criteria (OR 0.07, 95% CI 0.008 to 0.67, p=0.02), and patients with gBRCA1/2 mutations had improved progression-free survival (7.9 vs 2.5 months, HR 0.4, 95% CI 0.23 to 0.74, p=0.003) and overall survival (15.5 vs 6 months, HR 0.49, 95% CI 0.28 to 0.85, p=0.02) with metronomic cyclophosphamide when compared with patients without gBRCA1/2 mutations (or unknown gBRCA1/2 status).

Conclusion Oral metronomic cyclophosphamide showed a clinical benefit in 48% of patients with recurrent ovarian cancer. gBRCA1/2 status can be an independent predictor of response.