Inclusion Criteria:

          -  Participants with any of the following tumors who have experienced relapse following
             front-line therapy, or who are refractory to front-line therapy, and participants with
             tumors that carry a poor prognosis and have no known standard curative therapy

               -  Brain tumors of all World Health Organization (WHO) grades, except diffuse
                  intrinsic pontine glioma (DIPG)

               -  Extracranial solid tumors including histiocytoses

          -  Participants must have had a histologic verification of malignancy at original
             diagnosis or relapse, except in participants with optic pathway gliomas, or
             participants with pineal tumors and elevations of serum or cerebrospinal fluid (CSF)
             alpha-fetoprotein (AFP) or beta-human chorionic gonadotropin (beta-HCG)

          -  Tissue blocks or slides must be sent

          -  Participants must have radiographically measurable disease at the time of study
             enrollment to be eligible. Patients with neuroblastoma who do not have measurable
             disease but have metaiodobenzylguanidine (MIBG+) evaluable disease are eligible.

          -  Karnofsky performance level of greater than or equal to 50 percent for participants
             who are greater than 16 years of age at the time of screening

          -  Lansky performance level of greater than or equal to 50 percent for participants who
             are less than or equal to 16 years of age at the time of screening

          -  Fully recovered from acute toxic effects of all prior anti-cancer therapy

          -  Adequate bone marrow function as deemed by the protocol at the time of screening

          -  Adequate renal function as deemed by the study protocol at the time of screening

          -  Adequate liver function as deemed by the study protocol at the time of screening

          -  Serum triglyceride level ≤300 mg/dL and serum cholesterol ≤ 300 mg/dL

          -  Random or fasting blood glucose within the upper normal limits for age

          -  Adequate pulmonary function as deemed by the study protocol at the time of screening

        Exclusion Criteria:

          -  Women who are currently pregnant or breastfeeding

          -  Receiving corticosteroids who have not been on a stable dose for at least 7 days

          -  Currently receiving enzyme inducing anticonvulsants

          -  Currently receiving receiving potent CYP3A4 (enzyme) inducers or inhibitors

          -  Currently receiving another investigational drug

          -  Currently receiving any other anti-cancer agents

          -  The use of cannabis oil is prohibited during the first 2 cycles of this protocol.
             Patients must be off of cannabis oil for 3 days prior to enrollment.

          -  Uncontrolled infection

          -  Participants who in the opinion of the investigator may not be able to comply with the
             safety monitoring requirements