Brentuximab Vedotin After Donor Stem Cell Transplant in Treating Patients With Hematologic Malignancies

PRIMARY OBJECTIVES: I. To determine the incidence of durable donor hematopoietic engraftment (defined by donor T-cell chimerism \> 50% at day +84 after hematopoietic cell transplantation \[HCT\]) after allogeneic HCT and post-transplant brentuximab vedotin. SECONDARY OBJECTIVES: I. Rates of complete and partial response; incidence of acute graft-versus-host disease (GVHD) grades II-IV and chronic GVHD; overall and progression-free survival; rates of serious adverse events associated with brentuximab vedotin. OUTLINE: Patients receive brentuximab vedotin intravenously (IV) on day 1. Treatment repeats every 21 days for up to 16 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up for 5 years.