A phase II trial of arzoxifene,a selective estrogen response modulator,in patients with recurrent or advanced endometrial cancer

OBJECTIVES: The goal of this study was to determine response rate and evaluate toxicity of LY353381 (arzoxifene) in patients with recurrent or advanced endometrial cancer (EC). METHODS: A phase II, open-labeled study with arzoxifene was performed at 13 centers. Patients with measurable recurrent/advanced EC not amenable to curative therapies were eligible if either the primary tumor or recurrent tumor was ER+ and/or PR+. If receptor status could not be determined, patients with well or moderately well-differentiated EC were also permitted. Prior use of salvage chemotherapy was not allowed; however, prior use of progestagens was permitted and patients were stratified by prior exposure to progestagen. Patients received 20 mg/day PO, and were treated for at least 8 weeks in the absence of disease progression or unacceptable toxicity. Efficacy was based on the frequency of complete (CR) and partial (PR) responses, and a 95% confidence interval (CI) was calculated. The Kaplan-Meier method was used to analyze time to progression and duration of response. RESULTS: From February 1999 through April 2001, 37 patients were entered of whom 34 received treatment. Efficacy was evaluated for the 29 patients who received at least 4 weeks of therapy and at least one tumor response assessment. Safety was assessed in all 34 patients who received any drug. Thirty patients were defined as progestagen sensitive, and 4 patients were defined as progestagen failures. Twenty-six patients were ER+, and 22 were PR+. Nine (1 CR + 8 PR) of 29 patients responded (31%, CI 25-51%), with a median duration of response of 13.9 months. All 9 responses occurred in progestagen-sensitive patients. Two additional patients (one from each progestagen cohort) had stable disease for >or=6 months. The median progression-free interval was 3.7 months (CI 1.9-6.6 months) for all 29 patients. Toxicity was minimal with no grade 3-4 toxic effects, and 9 patients had only grade 1-2 toxic effects (7 grade 1, 2 grade 2). Hot flashes were the most common toxic effect and, in all 3 reported cases, were grade 1. CONCLUSIONS: Arzoxifene has demonstrated a high response rate with the longest median duration of response reported in a phase II trial of this patient population. The ease of administration and extremely favorable toxicity profile make this an agent warranting further evaluation.