Background: Platinum-resistant ovarian cancer (PROC) constitutes a therapeutic dilemma with limited efficacy from traditional cytotoxic agents. Based on prior data suggesting that scheduling alterations of platinum would increase activity, the aim of the present study was to assess the potential therapeutic benefit of phenoxodiol (PXD), a novel biomodulator shown to have chemoresistance reversing potential, when combined with weekly AUC2-carboplatin in PROC patients.
Patients and methods: A multicenter randomized double-blind placebo controlled phase-III-study was conducted to compare oral PXD plus AUC2-carboplatin (group 1) versus placebo plus AUC2-carboplatin (group 2) weekly in PROC patients. The primary end point was progression-free-survival (PFS). Secondary objectives included overall survival (OS), response rates, duration of response and quality of life.
Results: The study was terminated early 14 April 2009, after recruitment of 142 patients due to feasibility and recruitment challenges. A total of 142 patients were randomized. The groups were well balanced in terms of important baseline characteristics. The median PFS for group 1 was 15.4 weeks [95% confidence interval (CI) 11.1-21.0] versus 20.1 weeks for group 2 (95% CI = 13.1-33.4); P = 0.3. The objective response rate and median survival in group 1 versus group 2 was 0% versus 1% and 38.3 weeks (95% CI 32.0-45.3) versus 45.7 weeks (95% CI 35.6-58.0), respectively. PXD appeared to be well tolerated. The main reason for dose modification in both groups was hematologic toxicity.
Conclusions: Orally delivered PXD showed no evidence of clinical activity, when combined with weekly AUC2-carboplatin in PROC. In addition, single-agent weekly AUC2-carboplatin appeared to be inactive by response criteria in a homogenously defined population of PROC. This has implications for the design of future studies.
Trial registration: ClinicalTrials.gov NCT00382811.
Keywords: carboplatin; ovarian cancer relapse; phenoxodiol; platinum resistance; reversal; survival.