Phase II trial of the histone deacetylase inhibitor belinostat in women with platinum resistant epithelial ovarian cancer and micropapillary (LMP) ovarian tumours

Aim: Micropapillary/borderline (LMP) ovarian tumours are rarely included in clinical trials and are intrinsically resistant to radiation and chemotherapy. Platinum resistant epithelial ovarian cancer (EOC) has a poor prognosis. The histone deacetylase inhibitor belinostat demonstrated antitumour activity in pre-clinical ovarian cancer models. Methods: A phase II study was performed to evaluate the activity of belinostat in two patient populations: women with metastatic or recurrent platinum resistant (progression within 6 months) EOC and LMP ovarian tumours, both groups had received no more than 3 prior lines of chemotherapy. Belinostat 1000 mg/m2/d was administered iv days 1-5 of a 21 d cycle. Peripheral blood mononuclear cells (PBMCs) and tumour biopsies, where possible, for correlative studies were obtained prior to and following treatment. Results: Eighteen patients with EOC and 14 patients with LMP tumours were enrolled on study. Belinostat was well tolerated with no grade four toxicity (179 cycles). Grade 3 toxicity consisted of thrombosis (3 patients), hypersensitivity (1) and elevated ALP (1). One patient with LMP tumour had a partial response (unconfirmed) and 10 had stable disease (SD), 3 were non-evaluable. Median progression-free survival (PFS) was 13.4 months (95% confidence interval (CI), 5.6 - not reached). Best response in patients with EOC was SD (nine patients) and median PFS was 2.3 months (95% CI, 1.2-5.7 months). An accumulation of acetylated histones H3 and H4 was noted in PBMCs and in tumour tissue. Conclusions: Belinostat is well tolerated in both patient groups and shows some activity in patients with micropapillary (LMP) disease.