A Study to Evaluate the Safety, Tolerability, Drug Levels, and Preliminary Efficacy of Relatlimab Plus Nivolumab in Pediatric and Young Adults With Hodgkin and Non-Hodgkin Lymphoma

Inclusion Criteria:

1. Pathologically confirmed high-risk recurrent/relapsed or refractory (R/R) classical Hodgkin lymphoma (cHL), after non-response to or failure of first-line standard therapy prior to a definitive therapy e.g.high-dose chemotherapy/autologous stem cell transplant (HDCT/ASCT)
2. Participants with pathologically confirmed R/R NHL after failure or non-response to second line therapy, including but not limited to primary mediastinal B-cell lymphoma, diffuse large B-cell lymphoma (DLBCL), mediastinal gray zone lymphoma (MGZL), anaplastic large cell lymphoma (ALCL), or peripheral T-cell lymphoma (PTCL).
3. Participants must have measurable PET positive disease in both cHL and NHL cohorts.

Exclusion Criteria:

1. Aggressive B-cell lymphomas subtypes including Burkitt lymphoma (BL), lymphoblastic lymphoma, and NK/T-cell lymphoma/leukemia.
2. Primary CNS lymphoma of the brain or spinal cord, and secondary CNS lymphoma (ie, from systemic non-Hodgkin lymphoma) involving the brain, spinal cord, or with leptomeningeal seeding.
3. Prior treatment with an anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4) antibody, or any other antibody or drug specifically targeting T-cell co-stimulation or checkpoint pathways, with the exception of anti-PD(L)-1 targeted therapies
4. Prior treatment with lymphocyte activation gene-3 (LAG-3)-targeted agents
5. Prior autologous stem cell transplantation (HDCT/ASCT)
6. History of allogeneic bone marrow transplantation.

Other protocol-defined inclusion/exclusion criteria apply