Inclusion Criteria:

Among other criteria, patients must meet the following conditions to be eligible for the
study:

1. Adult patients, ≥ 18 years old

2. Newly diagnosed glioblastoma

3. Attempted surgical resection followed by conventional chemoradiation

4. Documented EGFRvIII positive tumor status by a Sponsor designated laboratory

5. No evidence of progressive disease from the post-operative period to the
post-chemoradiation period

6. Candidate for, and agrees to receive, adjuvant (maintenance) temozolomide therapy

7. Systemic corticosteroid therapy at ≤2 mg of dexamethasone or equivalent per day for
at least 3 days prior to randomization

8. WHO-ECOG Performance Status ≤ 2

9. Patients of childbearing/reproductive potential will be instructed to use birth
control as defined by your doctor.

Exclusion Criteria:

Among other criteria, patients who meet the following conditions are NOT eligible for the
study:

1. Stereotactic biopsy only (without further surgical resection)

2. Presence of diffuse leptomeningeal disease, gliomatosis cerebri, or infratentorial
disease.

3. History, presence, or suspicion of metastatic disease

4. Patients who have received any additional treatment for glioblastoma, aside from
surgical resection and chemoradiation with temozolomide

5. Active systemic infection requiring treatment

6. History of any malignancy (other than glioblastoma) during the last three years
except non-melanoma skin cancer, in situ cervical cancer, treated superficial bladder
cancer or cured, early-stage prostate cancer in a patient with PSA level less than
the upper limit of normal

7. Planned major surgery

8. Evidence of current drug or alcohol abuse

9. Known allergy or hypersensitivity to keyhole limpet hemocyanin (KLH), GM-CSF
(sargramostim; LEUKINE®), polysorbate 80 or yeast derived products, or a history of
anaphylactic reactions to shellfish proteins

10. Severe acute or chronic medical or psychiatric condition or laboratory abnormality
that could increase the risk associated with participating in a clinical trial

11. Women who are pregnant of lactating