A Study to Evaluate the Safety and Efficacy of Nivolumab Monotherapy and Nivolumab in Combination With Ipilimumab in Pediatric Participants With High Grade Primary Central Nervous System (CNS) Malignancies

Phase Ib /II Clinical Trial of Nivolumab Monotherapy and Nivolumab in Combination With Ipilimumab in Pediatric Subjects With High Grade Primary CNS Malignancies

The purpose of this study is to determine the safety and effectiveness of nivolumab alone and in combination with ipilimumab in pediatric patients with high grade primary central nervous system (CNS) malignancies.

Inclusion Criteria:

• Must have received standard of care therapy, and there must be no potentially-curative treatment available, in one of the following cohorts:
• A newly diagnosed Diffuse Intrinsic Pontine Glioma (DIPG) that has been treated with radiation therapy (RT) but no chemotherapy
• A histologically confirmed recurrent or progressive non-brainstem High Grade Glioma (HGG) previously treated with surgical resection and RT
• A histologically confirmed medulloblastoma that has relapsed or is resistant to at least one line of prior therapy including surgery, RT, and chemotherapy
• A histologically confirmed ependymoma that has relapsed or is resistant to at least one line of prior therapy including surgical resection and RT
• A histologically-confirmed high grade CNS malignancy "other than above" which is recurrent or progressive after at least one line of prior therapy
• Lansky play score (LPS) for ≤ 16 years of age or Karnofsky performance scale (KPS) for > 16 years of age assessed within two weeks of enrollment must be >= 60
• A tumor sample must be available for submission to central laboratory (not required for DIPG)

Exclusion Criteria:

• An active, known, or suspected autoimmune disease
• A concurrent condition requiring systemic treatment with either corticosteroids or other immunosuppressive medications within 14 days of start of study treatment
• Known history of positive test for human immunodeficiency virus (HIV) or known acquired immunodeficiency syndrome (AIDS).

Other protocol defined inclusion/exclusion criteria apply