A Safety and Efficacy Study of Combined Fianlimab + Cemiplimab in Children and Young Adults With Recurrent or Progressive High-Grade Glioma or Posterior Fossa-A Ependymoma

Key Inclusion Criteria:

• Participant must be diagnosed with recurrent/progressive HGG or PF-A ependymoma with unequivocal progression on Magnetic Resonance Imaging (MRI) as described in the protocol
• Participant must have histologically confirmed (at initial diagnosis or relapse) HGG or PF-A ependymoma
• Participant must be an adequate medical candidate for surgical resection as described in the protocol
• Karnofsky Performance Status (KPS) score ≥50 (in participants ≥16 years) or Lansky Performance Status (LPS) score ≥50 (in participants <16 years) as described in the protocol
• Adequate organ function as described in the protocol

Key Exclusion Criteria:

• Active autoimmune disease requiring systemic immunosuppressive therapy in the past 2 years
• Active, serious medical illness, infection or other systemic illness which would limit participation in the trial
• Has not yet recovered from any acute toxicities resulting from prior therapy
• History of myocarditis
• Prior treatment with antibodies to Programmed Cell Death Protein -1 (PD-1), Programmed Cell Death Protein Ligand -1 (PD-L1), Lymphocyte Activation Gene 3 (LAG3), or Cytotoxic T-Lymphocyte Associated protein 4 (CTLA-4)
• Treatment with high dose systemic corticosteroids as described in the protocol
• History of interstitial lung disease (eg, idiopathic pulmonary fibrosis, organizing pneumonia) or active, noninfectious pneumonitis that required immune-suppressive doses of glucocorticoids to assist with management

Note: Other protocol defined Inclusion/ Exclusion Criteria apply