Inclusion Criteria:

          -  Male or female subject ≥18 and ≤75 years of age

          -  Provision of written informed consent for tumor resection, stereotactic surgery, tumor
             biopsy, samples collection, and treatment with investigational products prior to
             undergoing any study specific procedures

          -  Histologically confirmed supratentorial glioblastoma

          -  Evidence of tumor recurrence/progression by magnetic resonance imaging (MRI) according
             to response assessment in neuro-oncology (RANO) criteria after standard initial
             therapy

          -  Previous standard-of-care antitumor treatment including surgery and/or biopsy and
             chemoradiation. At the time of registration, subjects must have recovered from the
             toxic effects of previous treatments as determined by the treating physician. The
             washout periods from prior therapies are intended as follows: (windows other than what
             is listed below should be allowed only after consultation with the Medical Monitor)

               1. Nitrosureas: 6 weeks

               2. Other cytotoxic agents: 4 weeks

               3. Antiangiogenic agents, including bevacizumab: 4weeks

               4. Targeted agents, including small molecule tyrosine kinase inhibitors: 2 weeks

               5. Vaccine-based therapy: 3 months

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

          -  Karnofsky Performance Status ≥70%

          -  Adequate bone marrow reserves and liver and kidney function, as assessed by the
             following laboratory requirements:

               1. Hemoglobin ≥9 g/L

               2. Lymphocytes >500/mm3

               3. Absolute neutrophil count ≥1500/mm3

               4. Platelets ≥100,000/mm3

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

               6. Aspartate transaminase (AST) and alanine transaminase (ALT) ≤2.5 x ULN. For
                  subjects with documented liver metastases, ALT and AST ≤5 x ULN

               7. Total bilirubin < 1.5 x ULN

               8. International normalized ratio (INR) and aPTT within normal institutional limits

          -  Male and female subjects must agree to use a highly reliable method of birth control
             (expected failure rate <5% per year) from the Screening Visit through 28 days after
             the last dose of study drug. Women of childbearing potential (perimenopausal women
             must be amenorrheic for at least 12 months to be considered of non-childbearing
             potential) must have a negative pregnancy test at screening.

          -  Normal cardiac and pulmonary function as evidenced by a normal ECG and peripheral
             oxygen saturation (SpO2) ≥90% by pulse oximetry

        Exclusion Criteria:

          -  Previous treatment with inhibitors of immunocheckpoint pathways (eg, anti-PD-1,
             anti-PD-L1, anti-PD-L2, anti-CD137, or anti-CTLA-4 antibody) or other agents
             specifically targeting T cells

          -  Radiotherapy treatment within 4 weeks or less prior to veledimex dosing

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

          -  Known immunosuppressive disease, or autoimmune conditions, and/or chronic viral
             infections (eg, human immunodeficiency virus [HIV], hepatitis)

          -  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.

          -  Use of enzyme inducing antiepileptic drugs (EIAED) within 7 days prior to the first
             dose of study drug. Note: Levetiracetam (Keppra®) is not an EIAED and is allowed.

          -  Other concurrent clinically active malignant disease, requiring treatment, with the
             exception of non-melanoma cancers of the skin or carcinoma in situ of the cervix or
             nonmetastatic prostate cancer

          -  Nursing or pregnant females

          -  Prior exposure to veledimex

          -  Use of medications that induce, inhibit, or are substrates of cytochrome p450 (CYP450)
             3A4 within 7 days prior to veledimex dosing without consultation with the Medical
             Monitor

          -  Presence of any contraindication for a neurosurgical procedure

          -  Unstable or clinically significant concurrent medical condition that would, in the
             opinion of the Investigator or Medical Monitor, jeopardize the safety of a subject
             and/or their compliance with the protocol. Examples include, but are not limited to:
             unstable angina, congestive heart failure, myocardial infarction within 2 months of
             screening, ongoing maintenance therapy for life-threatening ventricular arrhythmia or
             uncontrolled asthma.

          -  History of myocarditis or congestive heart failure (as defined by New York Heart
             Association Functional Classification III or IV), as well as unstable angina, serious
             uncontrolled cardiac arrhythmia, uncontrolled infection, or myocardial infarction 6
             months prior to study entry.