Inclusion Criteria:

- Subjects must have histologically proven neuroblastoma or medulloblastoma and
confirmation of refractory or recurrent disease with histologic confirmation at
diagnosis or at the time of recurrence/progression

- Subjects must be age >12 months and diagnosed before the age of 21

- Measurable disease, including at least one of the following:

- Measurable tumor >10mm by CT or MRI

- Positive bone marrow biopsy/aspirate.

- Positive MIBG

- Current disease state must be one for which there is currently no known curative
therapy

- Lansky Play Score or Karnofsky scale must be more than 30

- Subjects without bone marrow metastases must have an ANC > 750/μl and platelet count
>50,000/μl

- Adequate Renal Function Defined As

- Creatinine clearance or radioisotope GFR ≥ 70ml/min/1.73 m2 or

- A serum creatinine based on age/gender

- Adequate liver function must be demonstrated, defined as:

- Total bilirubin ≤ 1.5 x upper limit of normal (ULN) for age

- SGPT (ALT) < 10 x upper limit of normal (ULN) for age

- SGOT (AST) < 10x upper limit of normal (ULN) for age

- No other significant organ toxicity defined as > Grade 2 by National Cancer Institute
Common Toxicity Criteria for Adverse Events (NCI-CTCAE V4.0-
http://ctep.cancer.gov/forms/CTCAEv4.pdf)

- A negative urine pregnancy test is required for female participants of child bearing
potential (≥13 years of age or after onset of menses)

- Both male and female post-pubertal study subjects need to agree to use one of the
more effective birth control methods during treatment and for six months after
treatment is stopped. These methods include total abstinence (no sex), oral
contraceptives ("the pill"), an intrauterine device (IUD), levonorgestrol implants
(Norplant), or medroxyprogesterone acetate injections (Depo-provera shots). If one of
these cannot be used, contraceptive foam with a condom is recommended.

- Informed Consent: All subjects and/or legal guardians must sign informed written
consent. Assent, when appropriate, will be obtained according to institutional
guidelines

- Subjects may have received microtubulin inhibitors during previous therapies.

Exclusion Criteria:

- Anti-cancer Agents: Subjects who are currently receiving other anticancer agents are
not eligible. Subjects must have fully recovered from the effects of prior
chemotherapy (hematological and bone marrow suppression effects), generally at least
3 weeks from the most recent administration (6 weeks for nitrosoureas).

- Subjects who have received any myeloablative therapy within the previous 2 months.

- Subjects receiving anti-tumor therapy for their disease or any investigational drug
concurrently

- Subjects with serious infection or a life-threatening illness (unrelated to tumor)
that is > Grade 2 (NCI CTCAE V4.0), or active, serious infections requiring
parenteral antibiotic therapy.

- Subjects with any other medical condition, including malabsorption syndromes, mental
illness or substance abuse, deemed by the Investigator to be likely to interfere with
the interpretation of the results or which would interfere with a patient's ability
to sign or the legal guardian's ability to sign the informed consent, and patient's
ability to cooperate and participate in the study

- Subjects with known hypersensitivity to any of the components of the drugs to be
administered on study