Pembrolizumab After ASCT for Hodgkin Lymphoma, DLBCL and T-NHL

Inclusion criteria • Histologically confirmed diagnosis with review of the diagnostic pathology specimen at one of the participating institutions. Eligible histologies are: Arm A: Diffuse large B cell lymphoma; patients with a prior history of indolent B-cell NHL are eligible, as long as they have histologically confirmed DLBCL prior to their pre-transplant salvage treatment. Patients with mediastinal large B cell lymphoma are also eligible. Arm B: Classical Hodgkin lymphoma (patients with nodular lymphocyte predominant Hodgkin lymphoma \[NLPHL\] are NOT eligible) Arm C: Peripheral T cell lymphoma - eligible subtypes will include PTCL, NOS; AITL; and ALK-negative ALCL. Patients with other PTCL histologies, including ALK-positive PTCL, and cutaneous T-cell lymphoma will not be eligible.. * Age ≥ 18 at the time of enrollment. * For arms A and B, participants must have relapsed after or been refractory to first-line chemotherapy, i.e., they must have failed to achieve CR after first-line therapy or must have relapsed subsequently if they achieved CR. For arm C, participants will be eligible if transplant is performed as consolidation of first remission (partial or complete). * Participants must be planning to receive or have received autologous stem cell transplantation. Participants must have chemosensitive disease prior to ASCT, defined as achieving at least a partial remission (as determined with PET imaging) to salvage treatment. Participants with cHL or DLBCL (arms A and…