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A Phase 2, Randomized, Open-Label Study of Irosustat Versus Megestrol Acetate in Advanced Endometrial Cancer
  1. Patricia Pautier, MD,
  2. Ignace Vergote, MD, PhD,
  3. Florence Joly, MD,
  4. Bohuslav Melichar, MD,
  5. Elzbieta Kutarska, MD,
  6. Geoffrey Hall, MD,
  7. Anna Lisyanskaya, MD,
  8. Nicholas Reed, MD,
  9. Ana Oaknin, MD,
  10. Valerijus Ostapenko, MD,
  11. Zanete Zvirbule, MD,
  12. Eric Chetaille, MD,
  13. Agnès Geniaux, PhD,
  14. Muhammad Shoaib, MD and
  15. John A. Green, MD
  1. * Gustave Roussy Cancer Campus, Villejuif, France;
  2. Leuven Cancer Institute, Leuven, Belgium;
  3. Centre François Baclesse, Caen, France;
  4. § Palacky University Medical School and Teaching Hospital, Olomouc, Czech Republic;
  5. Centrum Onkologii Ziemi Lubelskiej, Lublin, Poland;
  6. Leeds Cancer Centre, St James University Hospital, Leeds, United Kingdom;
  7. # City Clinical Oncology Dispensary, St Petersburg, Russia;
  8. ** Gartnavel General Hospital, Glasgow, United Kingdom;
  9. †† Vall d'Hebron University Hospital, Vall d'Hebron Institute of Oncology, Barcelona, Spain;
  10. ‡‡ Vilnius University Institute of Oncology, Vilnius, Lithuania;
  11. §§ Oncology Centre of Latvia, Riga East University Hospital, Riga, Latvia;
  12. Ipsen Innovation, Les Ulis, France; and
  13. ¶¶ Clatterbridge Cancer Centre, University of Liverpool, Bebington, Merseyside, United Kingdom.
  1. Address correspondence and reprint requests to Patricia Pautier, MD, Gustave Roussy Cancer Campus, 114 Rue Édouard Vaillant, 94805 Villejuif, France. E-mail: patricia.pautier{at}


Objective Advanced/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.

Methods This 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.

Results Seventy-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.

Conclusions Although 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.

  • Advanced/recurrent endometrial cancer
  • Hormone therapy
  • Irosustat
  • Megestrol acetate
  • Overall survival
  • Progression-free survival

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  • The authors declare no conflicts of interest.