A Study of Ad-RTS-hIL-12 + Veledimex in Pediatric Subjects With Brain Tumors or DIPG

Eligible patients will be stratified to one of two arms, according to clinical indication for
tumor resection. Pediatric patients who are scheduled for craniotomy and tumor resection will
receive one dose of veledimex before the resection procedure. Ad-RTS-hIL-12 will be
administered by free-hand injection. Patients will continue on oral veledimex for 14 days.

Pediatric patients with diffuse intrinsic pontine glioma (DIPG) will receive Ad-RTS-hIL-12 by
stereotactic injection and then will continue on oral veledimex for 14 days.

The study is divided into three periods: the screening period, the treatment period and the
follow-up period.

Inclusion Criteria:

1. Male or female subjects ≤ 21 years-of-age with the demonstrated ability to swallow
capsules whole and who are willing to provide access to previously obtained biopsy
results

2. Provision of written informed consent and assent, when applicable, for tumor
resection, stereotactic surgery, tumor biopsy, sample collection, and/or treatment
with study drug prior to undergoing any study-specific procedures

3. Arm 1: Evidence of recurrent or progressive supratentorial tumor, which has shown a >
25% increase in bi dimensional measurements by MRI or is refractory with significant
neuro deterioration that is not otherwise explained with no known curative therapy.

Arm 2: Clinical presentation of DIPG and compatible MRI with approximately 2/3 of the
pons included. Subject should be ≥ 2 weeks and ≤ 10 weeks post standard focal
radiotherapy (ie, dose of 5400 to 5960 cGy and maximum dexamethasone of 1 mg/m2/day)

4. At the time of registration, subjects must have recovered from the toxic effects of
previous treatments, as determined by the treating physician.

1. Targeted agents, including small-molecular tyrosine kinase inhibitors: 2 weeks

2. Other cytotoxic agents: 3 weeks

3. Nitrosoureas: 6 weeks

4. Monoclonal antibody immunotherapies (eg, PD-1, CTLA-4): 6 weeks

5. Vaccine-based and/or viral therapy: 3 months

5. On a stable or decreasing dose of dexamethasone for the previous 7 days

6. Able to undergo standard MRI scans with contrast agent before enrollment and after
treatment

7. Have age-appropriate functional performance:

1. Lansky score ≥ 50 or

2. Karnofsky score > 50 or

3. Eastern Cooperative Oncology Group (ECOG) score ≤ 2

8. Have adequate bone marrow reserves and liver and kidney function, as assessed by the
following laboratory requirements:

1. Hemoglobin ≥ 8 g/L

2. Absolute lymphocyte count ≥ 500/mm3

3. Absolute neutrophil count ≥ 1000/mm3

4. Platelets ≥ 100,000/mm3 (untransfused [> 5 days] without growth factors)

5. Serum creatinine ≤ 1.5 x upper limit of normal (ULN) for age

6. Aspartate transaminase (AST) and alanine transaminase (ALT) ≤ 2.5 x ULN for age

7. Total bilirubin < 1.5 x ULN for age

8. International normalized ratio (INR) and activated thromboplastin time within
normal institutional limits

9. Male and female subjects of childbearing potential must agree to use a highly reliable
method of birth control (expected failure rate < 1% per year) from the Screening Visit
through 28 days after the last dose of study drug. Women of childbearing potential
must have a negative pregnancy test at screening.

Exclusion Criteria:

1. Radiotherapy treatment prior to the first veledimex dose:

1. Focal radiation ≤ 4 weeks

2. Whole-brain radiation ≤ 6 weeks

3. Cranio-spinal radiation ≤ 12 weeks NOTE: Subjects in Arm 2 (ie, with DIPG) must
be ≥ 2 weeks and ≤ 10 weeks after standard focal radiotherapy (dose of 5400 to
5960 cGy and maximum dexamethasone of 1 mg/m2/day)

2. Subjects with clinically significant increased intracranial pressure (eg, impending
herniation or requirement for immediate palliative treatment) or uncontrolled seizures

3. Subjects whose body surface area (BSA) would expose them to < 75% or > 125% of the
target dose

4. Known immunosuppressive disease, autoimmune condition, and/or chronic viral infection
(eg, human immunodeficiency virus [HIV], hepatitis)

5. Use of systemic antibacterial, antifungal, or antiviral medications for the treatment
of acute clinically significant infection within 2 weeks of first veledimex dose.
Concomitant therapy for chronic infections is not allowed. Subjects must be afebrile
prior to Ad-RTS-hIL-12 injection; only prophylactic antibiotic use is allowed
perioperatively

6. Use of enzyme-inducing antiepileptic drugs (EIAEDs) within 7 days prior to the first
dose of study drug

7. Other concurrent clinically active malignant disease, requiring treatment

8. Nursing or pregnant females

9. Prior exposure to veledimex

10. Use of medications that induce, inhibit, or are substrates of cytochrome p450 (CYP450)
3A4 within 7 days prior to veledimex

11. Use of heparin or acetylsalicylic acid (ASA)

12. Presence of any contraindication for a neurosurgical procedure

13. Unstable or clinically significant concurrent medical condition