Randomized phase II study of decitabine in combination with carboplatin compared with carboplatin alone in patients with recurrent advanced ovarian cancer

Abstract

5562 Background: Experimental and clinical data (Gifford et al, Clin Cancer Res. 2004) indicate the potential importance of methylation in mediating resistance to carboplatin in ovarian cancer. A previous phase I trial (Appleton et al, J Clin Oncol. 2007) established the feasibility of combining carboplatin with the demethylating agent decitabine on a day 1 + 8 q4 weekly (w) schedule and PD data provided evidence of target cell demethylation. Methods: Patients (pt) with ovarian cancer relapsing 6–12 months following first line treatment were randomised to receive either 6 cycles of carboplatin AUC 6 q4 w (Arm A), or 90 mg/m2 decitabine as a 6 hour infusion on day 1 and carboplatin AUC 6 on day 8 q4 w (Arm B). The primary endpoint was response rate. An interim analysis was planned after 11 patients were enrolled into Arm B. Results: 29 pt were enrolled. After the first 4 pt had been treated (at 90 mg/m2 decitabine) the frequency of dose delays due to neutropenia was considered unacceptable, and therefore the starting dose of decitabine was reduced to 45 mg/m2 for the subsequent 11 pt. 7 out of 14 pt in Arm A completed 6 cycles compared with 0 of 11 in Arm B (at 45 mg/m2 decitabine). Grade 2/3 hypersensitivity reactions were more common in Arm B than Arm A (64% vs. 21%), as were prolonged treatment delays due to neutropenia (36% vs. 10%). At the interim analysis, in the 11 pt treated with 45mg/m2 (Arm B), there were no RECIST responses, while 2 pt had short-lived CA125 responses (59 and 63 days). In contrast 6 of 14 patients in Arm A had RECIST responses consistent with the expected efficacy of carboplatin in this population. Conclusions: The lack of efficacy, as well as the difficulties in treatment delivery in Arm B, led the project team to conclude that the study should be closed. With this dose and schedule, decitabine is ineffective in reversing carboplatin resistance. Further investigations are ongoing to understand (a) the apparent increased incidence of hypersensitivity and (b) the trend towards reduced efficacy in Arm B. [Table: see text]