A Phase 3, Randomized, Double-Blind, Placebo-Controlled Study of Optune®(TTFields, 200 kHz) Concomitant with Maintenance Temozolomide andPembrolizumab Versus Optune® Concomitant with Maintenance Temozolomide andPlacebo for the Treatment of Newly

The purpose of this study is to compare the effects of pembrolizumab simultaneously with the Optune device and maintenance temozolomide (TMZ) versus placebo simultaneously with Optune and maintenance TMZ for the study treatment of newly diagnosed glioblastoma multiforme (GBM). In this study, a placebo is an inactive substance that looks the same as and is given the same way as pembrolizumab. The effects of pembrolizumab are compared to the effects of the placebo. Pembrolizumab is an immunotherapy and it works with your immune system to help fight cancer. Optune® device generates Tumor Treating Fields (TTFields) intended to destroy brain cancer cells. TTFields is a type of treatment for cancerous tumors. Laboratory studies demonstrated its potential effect of slowing down the growth of tumors, without causing significant side effects. Large clinical studies have confirmed the safety and efficacy of Optune® in patients with recurrent and newly diagnosed GBM. The currently approved treatment for newly diagnosed GBM includes the addition of Optune to the treatment with maintenance temozolomide, following the completion of chemoradiation therapy (radiotherapy (RT) + TMZ). Optune® has been approved for the treatment of recurrent and newly diagnosed GBM by the Food and Drug Administration (FDA) in the United States. Pembrolizumab is an experimental drug, which means The United States Food and Drug Administration (FDA) has not approved Pembrolizumab for the treatment of GBM. Similarly, the combination of pembrolizumab with Optune and temozolomide (TMZ) has not been approved for the treatment of GBM therefore it is experimental.

Are you Eligible? (Inclusion Criteria)

• Must be 18 years or older - Able to have magnetic resonance imaging (MRI) scan with contrast of the brain. - Must not have an infection that needs medicine taken throughout the body. - Has a new diagnosis of glioblastoma multiforme (GBM) according to World Health Organization (WHO) 2021 Classification.