ObjectiveAdvanced/metastatic or recurrent endometrial cancer has a poor prognosis. Malignant endometrial tissue has high steroid sulphatase (STS) activity. The aim of this study was to evaluate STS as a therapeutic target in patients with endometrial cancer.MethodsThis was a phase 2, multicenter, international, open-label, randomized (1:1), 2-arm study of the STS inhibitor oral irosustat 40 mg/d versus oral megestrol acetate 160 mg/d in women with advanced/metastatic or recurrent estrogen receptor–positive endometrial cancer. The primary end point was the proportion of patients without progression or death 6 months after start of treatment. Secondary end points included progression-free survival, time to progression, overall survival, and safety.ResultsSeventy-one patients were treated (36 with irosustat, 35 with megestrol acetate). The study was prematurely stopped after futility analysis. Overall, 36.1% and 54.1% of patients receiving irosustat or megestrol acetate had not progressed or died at 6 months, respectively. There were no statistically significant differences between irosustat and megestrol acetate in response and overall survival rates. Irosustat patients had a median progression-free survival of 16 weeks (90% confidence interval, 9.0–31.4) versus 40 weeks (90% confidence interval, 16.3–64.0) in megestrol acetate patients. Treatment-related adverse events occurred in 20 (55.6%) and 13 (37.1%) patients receiving irosustat or megestrol, respectively. Most adverse events in both groups were grade 1 or 2.ConclusionsAlthough irosustat monotherapy did not attain a level of activity sufficient for further development in patients with advanced/recurrent endometrial cancer, this study confirms the activity of hormonal treatment (megestrol acetate) for this indication.
IMPACT OF HORMONAL BIOMARKERS ON RESPONSE TO HORMONAL THERAPY IN ADVANCED AND RECURRENT ENDOMETRIAL CANCER: