Phase 1b-2a study to reverse platinum resistance through use of a hypomethylating agent, azacitidine, in patients with platinum-resistant or platinum-refractory epithelial ovarian cancer

Background: Sequential treatment with azacitidine can induce re-expression of epigenetically silenced genes through genomic DNA hypomethylation and reverse carboplatin resistance of epithelial ovarian cancer cells. A phase 1b-2a clinical trial of this sequential combination of azacitidine and carboplatin was initiated in patients with platinum-resistant or platinum-refractory epithelial ovarian cancer. Methods: Patients with pathologically confirmed intermediate-grade or high-grade epithelial ovarian cancer who developed disease progression within 6 months (resistant disease, n = 18 patients) or during a platinum-based therapy (refractory disease, n = 12 patients) were eligible. All patients had measurable disease. Results: Thirty patients received a total of 163 cycles of treatment. This regimen produced 1 complete response, 3 partial responses (overall response rate [ORR], 13.8%), and 10 cases of stable disease among 29 evaluable patients. For those patients who achieved clinical benefits, the median duration of the treatment was 7.5 months. The median progression-free survival (PFS) and overall survival (OS) for all patients were 3.7 months and 14 months, respectively. Patients with platinum-resistant disease achieved an ORR of 22%, with a median PFS of 5.6 months and a median OS of 23 months. The predominant toxicities were fatigue and myelosuppression. Correlative studies indicated that DR4 methylation in peripheral blood leukocytes was decreased during treatment in 3 of 4 objective responders (75%), but in only 5 of 13 nonresponders (38%). Conclusions: To the authors' knowledge, the results of the current study provide the first clinical evidence that a hypomethylating agent may partially reverse platinum resistance in patients with ovarian cancer. Further clinical evaluation of hypomethylating agents in combination with carboplatin is warranted.