A prospective multicenter study of sirolimus for complicated vascular anomalies.

Abstract Objective Complicated vascular anomalies (VAs) can be intractable and uncontrollable using conventional treatment and can result in lethal outcomes. We undertook a prospective, multicenter phase II trial to evaluate the efficacy and safety of sirolimus in pediatric patients with complicated VAs. Methods Eligible patients were required to be aged 0 to 14 years and to have a complicated VA. The patients were treated with daily oral sirolimus for 12 months. The primary endpoint was the response, which was measured using sequential volumetric magnetic resonance imaging. The secondary endpoints were the disease severity score and quality of life. Results Of 126 patients enrolled on an intention-to-treat basis, 98 (77.8%) had had an objective response to sirolimus, with a ≥20% decrease in lesion volume. Compared with those with arteriovenous malformations, the response rates were higher (>80%) for patients with common lymphatic malformations, venous malformations, kaposiform hemangioendothelioma, and combined malformations with a prominent venous and/or lymphatic component (P  Conclusions Sirolimus is an apparently effective option for pediatric patients with various types of complicated VAs. Close monitoring of possible adverse events is required. The results from the present trial are the basis for future prospective studies using new therapeutic approaches.