Anti-Lag-3 (Relatlimab) and Anti-PD-1 Blockade (Nivolumab) Versus Standard of Care (Lomustine) for the Treatment of Patients With Recurrent Glioblastoma

Inclusion Criteria: * Histologically-proven glioblastoma (World Health Organization \[WHO\] 2021 criteria) * Progressive or recurrent disease per Response Assessment in Neuro-Oncology (RANO) criteria * No IDH mutation (IDH1 R132H negative by immunohistochemistry \[IHC\] or sequencing) * Patients must be in first recurrence of glioblastoma following radiation therapy and temozolomide * No prior therapies except radiation, surgery, temozolomide, Tumor Treating Fields (TTFields), and/or Gliadel wafers (placed during the first surgery at diagnosis of glioblastoma multiforme \[GBM\]). Prior radiation therapy, TTFields, or placement of Gliadel wafers must be completed at least 2 weeks prior to registration. Prior temozolomide must be completed at least 3 weeks prior to registration * No prior use of nivolumab or other anti-PD1 agents * Patients must be neurologically stable off corticosteroids for at least 5 days prior to registration * Age: ≥ 18 years * Karnofsky Performance Status: ≥ 60% (i.e. patient must be able to care for themselves with occasional help from others) * Absolute lymphocyte count (ALC): ≥ 1000/mm\^3 * Absolute neutrophil count (ANC): ≥ 1500/mm\^3 * Platelet count: ≥ 100,000/mm\^3 * Hemoglobin: ≥ 9.0 g/dL * Activated partial thromboplastin time (APTT) or partial thromboplastin time (PTT): ≤ 1.5 x upper limit of normal (ULN) * Total bilirubin: \< 2.0 x ULN (Except for patients with Gilbert's syndrome, who must have direct bilirubin \< 2.0 x ULN) * Aspartate amino…