Low- vs High-Dose Sirolimus With Prednisolone for KHE and KMP

This randomized clinical trial evaluates if low-dose sirolimus (target trough 4-8 ng/mL) combined with prednisolone is noninferior in efficacy but superior in safety compared to standard high-dose sirolimus (target trough 10-15 ng/mL) combined with prednisolone in pediatric patients with kaposiform hemangioendothelioma and Kasabach-Merritt phenomenon (KHE with KMP), with participants randomized 1:1 to receive the assigned regimen, undergo routine blood and imaging monitoring, and be evaluated for clinical response and adverse events.

Inclusion Criteria: * Presenting a KHE with the following characteristics: 1. Clinical features and histological findings consistent with progressive, non-resectable KHE associated with KMP. 2. Patients must be 0 - 18 years of age at the time of study entry. 3. Without functional impairment requiring treatment of corticosteroid. * Organ function requirements: 1 Adequate liver function: 1. Total bilirubin less than or equal to 1.5 x upper limit of normal (ULN)for age, and 2. ALT and AST less than or equal to 2.5 x upper limit normal (ULN) for age. 2 Adequate renal function: 1. 0-5 years of age maximum serum creatinine (mg/dL) of 0.8 2. 6-10 years of age maximum serum creatinine (mg/dL) of 1.0 3. 11-15 years of age maximum serum creatinine (mg/dL) of 1.2 4. 16-18 years of age maximum serum creatinine (mg/dL) of 1.5 * Adequate bone marrow function: Absolute Neutrophil Count (ANC) greater than or equal to 1 x 10 to the ninth/Liter. * Consent of parents (or the person having parental authority in families): Signed and dated written informed consent. Exclusion Criteria: * Allergy to sirolimus or other rapamycin analogues. * Any known evidence of significant local or systemic uncontrolled infection, defined as receiving intravenous antibiotics at the time of randomization. * Patients must not be known to be Human Immunodeficiency Virus positive or known immunodeficiency. Testing is not required unless a condition is suspected. * Other concurrent severe and/or uncontrolled medical disease which could compromise participation in the study (e.g. uncontrolled diabetes, uncontrolled hypertension, severe malnutrition, chronic liver or renal disease, active upper gastrointestinal tract ulceration). * Impairment of gastrointestinal function or chronic gastrointestinal disease that may significantly alter the absorption of sirolimus. * Patients who have a history of malignancy. * Patients with an inability to participate or to follow the study treatment and assessment plan.