Inclusion Criteria:

- Patients with histologically confirmed diagnosis of MB, who have experienced relapse
or progression after standard-of-care therapy including radiotherapy with no prior
exposure to TMZ therapy. Patients currently receiving steroids must have been on a
stable (or decreasing) dose for at least 5 days before initiating study therapy.

- Only patients with a test result, using the 5-gene Hh signature assay, indicating
Hhpathway activated MB are eligible for this study. All available tumor material
obtained at any time during the course of the patient's disease should be submitted
for these analyses

- At least one measurable lesion defined as lesion(s) that can be accurately measured
in at least two dimensions and is ≥ 10 mm in each dimension by Gadolinium (Gd)-MRI,
irrespective of slice thickness/reconstruction interval, for CNS lesions and CT or
MRI (with or without contrast) for non-CNS lesions. All patients with CNS lesions
must have a brain MRI with and without gadolinium and a spine MRI with gadolinium
within 2 weeks prior to first dose of study treatment.

- Performance Status corresponding to ECOG score of 0, 1, or 2:

1. Karnofsky performance status score ≥ 50 for patients >16 years of age

2. Lansky performance status score ≥ 50 for patients ≤ 16 years of age

- Adequate bone marrow function as defined as:

1. Peripheral absolute neutrophil count (ANC) ≥ 1.5 x 109/L

2. Platelet count ≥ 100 x 109/L

3. Hemoglobin (Hgb) ≥ 9 g/dL

- Serum CK ≤1.5 ULN

Exclusion Criteria:

- Prior treatment with a Smoothened inhibitor Systemic anticancer treatment within 2
weeks before first dose of study treatment (6 weeks for nitrosourea, mitomycin, and
monoclonal antibodies).

- Focal radiation therapy within 4 weeks before first dose of study treatment, or full
spinal radiotherapy within 3 months before first dose of study treatment.

- Patients who have neuromuscular disorders that are associated with elevated CK (eg,
inflammatory myopathies, muscular dystrophy, amyotrophic lateral sclerosis, spinal
muscular atrophy).

- Patients receiving treatment with medications that are known to be strong inhibitors
or inducers of CYP3A4/5 or are metabolized by CYP2B6 and CYP2C9, that have narrow
therapeutic indices that cannot be discontinued at least 2 weeks before first dose of
study treatment and for the duration of the study

- Patients receiving unstable or increasing doses of corticosteroids. If patients are
on corticosteroids for endocrine deficiencies or tumor-associated symptoms, dose must
have been stabilized (or decreasing) for at least 5 days before first dose of study
treatment.

- History of hypersensitivity reaction to dacarbazine (DTIC), TMZ or any of its
components.