Could a lower drug dose be safer and just as effective for kids with rare tumor?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

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.