Inclusion Criteria:

          -  Patients must be ≥ 2 years and ≤ 21 years old at the time of study enrolment.

          -  Karnofsky ≥ 50% for patients > 16 years of age and Lansky ≥ 50 for patients ≤ 16 years
             of age

          -  Patients must have relapsed or refractory solid or CNS tumours or have a diagnosis of
             DIPG. Patients must have had histologic verification of malignancy at original
             diagnosis or relapse, or a diagnosis of DIPG by MRI imaging.

          -  Patients must have either measurable or evaluable disease for Part B of the study only

          -  Patient's current disease state must be one for which there is no known curative
             therapy or therapy proven to prolong survival with an acceptable quality of life.

          -  Patients must have fully recovered from the acute toxic effects of all prior
             chemotherapy, immunotherapy, or radiotherapy prior to entering this study

        Exclusion Criteria:

          -  Pregnant or breast-feeding women will not be entered on this study.

          -  Any active uncontrolled infection

          -  Patients who are known to be serologically positive for Hepatitis A, B or C, or have a
             history of liver disease, other forms of hepatitis or cirrhosis.

          -  Known positive test for human immunodeficiency virus infection

          -  Patients with disease of any major organ system that would compromise their ability to
             withstand therapy

          -  Concurrent or prior (within 7 days of enrolment) anticoagulation therapy, except low
             molecular weight heparins or low dose aspirin

          -  Patients receiving corticosteroids must be on a stable dose that has not been
             increased for at least 7 days prior to study enrolment.

          -  Patients who are currently receiving another investigational drug are ineligible.

          -  Patients who are currently receiving other antineoplastic agents are ineligible.

          -  All herbal supplements, vitamins, and nutritional supplements taken within the last 30
             days prior to dosing on Day 1 (and continued use, if appropriate), must be reviewed
             and approved by the Study Chair.

          -  Patient will not be available for protocol-required study visits or procedures, to the
             best of the subject/parent/guardian's and investigator's knowledge.

          -  Patient has any kind of disorder that, in the opinion of the investigator, may
             compromise the ability of the subject/parent/guardian to give written informed consent
             and/or to comply with all required study procedures.

          -  History or evidence of any other clinically significant disorder, condition or disease
             (with the exception of those outlined above) that, in the opinion of the investigator
             would pose a risk to subject safety or interfere with the study evaluation, procedures
             or completion.

          -  Patients will be screened for antibodies to S. typhimurium and will not be eligible
             until antibodies are non-detectable

          -  Patients will be screened for IL6 and TNFa cytokines and will not be eligible until
             levels are less than 3x times the detectable limit of the assay.