Inclusion Criteria:

          1. Adults, aged greater than or equal to 70 years, or aged 65-69 years if long course RT
             is inappropriate, with newly diagnosed histologically confirmed GBM (WHO grade IV
             glioma including gliosarcoma) following surgery

          2. Tissue available for MGMT testing

          3. ECOG 0-2

          4. Life expectancy of >12 weeks

          5. Adequate bone marrow function (platelets > 100 x 10^9/L, ANC > 1.5 x 10^9/L)

          6. Adequate liver function (ALT/AST < 1.5 x ULN)

          7. Adequate renal function (creatinine clearance > 30 ml/min measured using
             Cockroft-Gault

          8. Willing and able to comply with all study requirements, including treatment, timing
             and/or nature of required assessments including MRI

          9. Signed, written informed consent

        Exclusion Criteria:

          1. Specific comorbidities or conditions (e.g. psychiatric) or concomitant medications
             which may impact with the administration of study related treatments or procedures

          2. Other co-morbidities or conditions that may compromise assessment of key outcomes

          3. Prior chemotherapy or cranial radiation within the last 5 years. Prior or concomitant
             therapies for GBM (except surgery).

          4. History of another malignancy within 2 years prior to registration. Patients with a
             past history of adequately treated carcinoma-in-situ, basal cell carcinoma of the
             skin, squamous cell carcinoma of the skin, or superficial transitional cell carcinoma
             of the bladder are eligible. Patients with a history of other malignancies are
             eligible if they have been continuously disease free for at least 2 years after
             definitive primary treatment.

          5. Significant infection, including chronic active hepatitis B, hepatitis C, or HIV.
             Testing for these is not mandatory unless clinically indicated

          6. Active, known or suspected autoimmune disease. Subjects with type I diabetes mellitus,
             hypothyroidism only requiring hormone replacement, skin disorders (such as vitiligo,
             psoriasis or alopecia) not requiring systemic treatment, or conditions not expected to
             recur in the absence of an external trigger are permitted to enroll.

          7. For symptoms related to GBM, the need for >4 mg/day of dexamethasone or >20 mg/day
             prednisone (or equivalent) at the time of screening.

          8. For a condition other than GBM, the need for >2 mg/day of dexamethasone or >10 mg/day
             prednisone (or equivalent) or other immunosuppressive medications within 14 days prior
             to randomisation. Exceptions to this include the use of inhaled or topical steriods
             >10 mg/day prednisone (or equivalent), which are permitted in the absence of active
             autoimmune disease.