Clinical trial data has led Ipsen to stop further development of its anticancer candidate Irosustat (BN 83495) as monotherapy. The firm will, however, look into developing the drug in combination with other hormonal treatments.
The decision to drop Irosustat as a monotherapy candidate was made on the back of a Phase II trial in endometrial cancer, and Phase I/II data from studies in metastatic prostate and breast cancers. A futility analysis of the European endometrial cancer study showed that the primary progression endpoint would not be met, and indicated that superiority of Irosustat compared with megestrol acetate in terms of progression free survival would not be demonstrated.
Irosustat is an orally available irreversible steroid sulfatase inhibitor, and trial results have yielded some encouraging data, Ipsen stresses. Prior clinical studies have shown that treatment with Irosustat was well tolerated and resulted in prolonged partial responses linked with a significant inhibition of steroid sulfatase and thus marked reduction in levels of some circulating steroid hormones. This data has prompted the firm to explore the potential development of Irosustat in combination with other hormonal therapies against hormone-dependent cancers.