EF-41/KEYNOTE D58: Phase 3 Study of Optune Concomitant With Temozolomide Plus Pembrolizumab in Newly Diagnosed Glioblastoma

Inclusion Criteria:

1. The participant (or legally acceptable representative) has provided documentedinformed consent for the study.

2. Be ≥ 18 years of age on day of providing informed consent.

3. Participant with new diagnosis of GBM according to World Health Organization (WHO) 2021 Classification.

4. Recovered from maximal debulking surgery (gross total resection, partial resectionand biopsy-only patients are all acceptable), Gliadel wafers placement at the timeof surgical resection is allowed.

5. Have completed standard adjuvant chemoradiotherapy of radiotherapy (RT) according tolocal practice (56-64 Gy), and concomitant TMZ chemotherapy.

6. Amenable to treatment with Optune concomitant with maintenance TMZ (150-200 mg/m^2daily x 5, Q28 days).

7. Have an Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 to 1assessed within 7 days before randomization.

8. Stable or decreasing dose of corticosteroids (dexamethasone ≤ 2mg or equivalent) forthe last 7 days prior to randomization, if applicable.

Exclusion Criteria:

1. Has received prior therapy with an anti-Programmed Cell Death 1 (PD-1), anti-Programmed Cell Death-Ligand 1(PD-L1), or anti Programmed Cell Death-Ligand 2 (PD-L2) agent or with an agent directed to another stimulatory or co-inhibitoryT-cell receptor (e.g.Cytotoxic T-Lymphocyte-Associated protein 4 (CTLA-4), OX 40,CD137).

2. Ongoing requirement for >2 mg dexamethasone (or equivalent), due to intracranialmass effect.

3. Has received prior systemic anti-cancer therapy including investigational agentswithin 4 weeks prior to randomization.

4. Received a live or live-attenuated vaccine within 30 days before the first dose ofstudy intervention. Administration of killed vaccines are allowed.

5. Is currently participating in or has participated in a study of an investigationalagent or has used an investigational device within 4 weeks prior to the first studytreatment.

6. Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form ofimmunosuppressive therapy within 7 days prior the first dose of study medication.Has a known additional malignancy that is progressing or has required activetreatment within the past 3 years.

7. Has a history of (noninfectious) pneumonitis/interstitial lung disease that requiredsteroids or has current pneumonitis/interstitial lung disease.

8. Early progressive disease after the end of TMZ/RT. If pseudo progression issuspected, additional imaging studies should be performed to rule out trueprogression.

9. Infratentorial or leptomeningeal disease.