Inclusion Criteria:

          1. Ability to swallow capsules unless enrolled in Part E

          2. Body surface area (BSA): Subjects must have a body surface area ≥ 0.45 m2 at the time
             of the study enrollment, unless enrolled in Part E

          3. Disease status: Subjects must have measurable or evaluable disease, by RECIST v1.1 ±
             Curie Scale Criteria or RANO/RANO-BM

          4. Tumor type:

               -  Part A: Relapsed or refractory extracranial solid tumors and (Phase 1b expansion)
                  relapsed or refractory extracranial solid tumors with molecular alterations,
                  non-gene fusions;

               -  Part B: Relapsed or refractory primary CNS tumors with molecular alterations,
                  including gene fusions, documented by a CLIA-approved lab prior to enrollment;

               -  Part C: Relapsed or refractory neuroblastoma;

               -  Part D: Relapsed or refractory non-neuroblastoma, extracranial solid tumors with
                  NTRK1/2/3, ROS1, or ALK gene fusions documented by a CLIA-approved lab prior to
                  enrollment;

               -  Part E: Any patient unable to swallow capsules who otherwise meet all other
                  eligibility criteria for Part A (expansion) B, C or D

          5. Histologic/molecular diagnosis of malignancy at diagnosis or the time of relapse

          6. Archival tumor tissue from diagnosis or, preferably, at relapse

          7. Age: Male or female from birth to age < 22 years, unless enrolled in Part E

          8. Performance status: Lansky or Karnofsky score ≥ 60% and minimum life expectancy of at
             least 4 weeks

          9. Patient's cancer must have relapsed after or failed to respond to frontline curative
             therapy or there must not be other potentially curative treatment options available

         10. Adequate organ and neurologic function

         11. Females of child bearing potential must have a negative serum pregnancy test within 14
             days prior to entrectinib dosing

        Exclusion Criteria:

          1. Receiving other experimental therapy

          2. Known congenital long QT syndrome

          3. Known active infections

          4. Receiving Enzyme Inducing Antiepileptic Drugs (EIAEDs) within 14 days of first dose.

          5. Prior treatment with approved or investigational TRK, ROS1, or ALK inhibitors

          6. Patients with NB with bone marrow space-only disease

          7. Incomplete recovery from acute effects of any surgery prior to treatment.

          8. Active gastrointestinal disease or other malabsorption syndromes that would impact
             drug absorption.

          9. Other severe acute or chronic medical or psychiatric condition or lab abnormality that
             may increase the risk associated with study participation, drug administration or may
             interfere with the interpretation of study results.