Immune booster may strengthen stem cell transplant against hodgkin lymphoma

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Eligible for autologous stem cell transplant (ASCT) with BEAM conditioning regimen * KPS greater than 70 or ECOG ≤ 1 * Adequate organ function and blood counts within 14 days of study registration * Participants who are HBsAg positive are eligible if they have received HBV anti-viral therapy for at least 4 weeks, and have undetectable HBV viral load prior to randomization. * Participants with a history of HCV infection are eligible if HCV viral load is undetectable at screening. * HIV-infected participants must have well-controlled HIV on ART Exclusion Criteria: * Patients with prior history of any grade 2 or higher autoimmune reaction to PD-1 inhibitors, necessitating permanent discontinuation of the PD-1 inhibitor or necessitating systemic immunosuppressants. * Has received prior radiotherapy within 2 weeks of start of study intervention or radiation-related toxicities requiring corticosteroids. * Has received a live vaccine or live-attenuated vaccine within 30 days before the first dose of study intervention. Administration of killed vaccines is allowed. * Has received any chemotherapy within 3 weeks prior to the first dose of study intervention * Has known active CNS disease. * History of or active autoimmune disease, or other syndrome that requires systemic steroids or autoimmune agents. Exceptions: Participants with vitiligo, resolved childhood asthma or atopy, hypothyroidism, or Sjogren's syndrome, as well as participants requiring only intranasal steroids, intermittent use of bronchodilators, local steroid injections, or physiologic replacement doses of prednisone (≤ 10 mg/d) may enroll. * Has had an allogenic tissue/solid organ transplant. * Pregnant or breastfeeding as agents used in this study are Pregnancy Category D (positive evidence of risk). Females of childbearing potential must have a negative pregnancy test (serum or urine) within 14 days of study registration