• PFS at 6 months in Phase II
• Median OS in Phase III

• Establish the safety and tolerability profile(s) of the CDX-110 vaccination schedule in these patients. [ Time Frame: 2 years ] [ Designated as safety issue: Yes ]
• Assess humoral and cellular immune responses to CDX-110 vaccinations and explore the overall immunogenicity of the vaccine as well as any interactions with steroid dosing and maintenance temozolomide. [ Time Frame: 2 years ] [ Designated as safety issue: No ]
• Assess overall survival. [ Time Frame: indeterminate ] [ Designated as safety issue: No ]

• Safety
• Immune Response rate

This study is designed to evaluate the clinical activity of CDX-110 vaccination when given with standard of care treatment (maintenance temozolomide therapy). Study treatment will be given until disease progression and patients will be followed for long-term survival information. Efficacy will be measured by the progression-free survival status at 5.5 months from the date of first dose.

• Drug: PF-04948568 (CDX-110) with GM-CSF
• Drug: temozolomide

Inclusion Criteria:

• Newly diagnosed de novo GBM with documented EGFRvIII expression in tumor tissue.
• Gross total resection followed by conventional chemoradiation therapy without progression of disease.

Exclusion Criteria:

• Presence of diffuse leptomeningeal disease or gliomatosis cerebri.
• Systemic corticosteroid therapy > 2 mg of dexamethasone or equivalent (as defined by the investigator) per day at study enrollment.
• Patients who have undergone stereotactic radiosurgery prior to or following surgical resection, or the placement of Gliadel® Wafers.
• Known allergy or hypersensitivity to KLH, GM-CSF or yeast derived products, or a history of anaphylactic reactions to shellfish proteins.