Rituximab in Treating Patients Undergoing Donor Peripheral Blood Stem Cell Transplant for Relapsed or Refractory B-cell Lymphoma

PRIMARY OBJECTIVES: I. To determine the effect of addition of peri-transplant rituximab on relapse rate at 18 months after non-myeloablative allogeneic hematopoietic cell transplant (HCT) for cluster of differentiation (CD)20+ B-cell malignancies. SECONDARY OBJECTIVES: I. To determine overall and progression-free survival and non-relapse mortality. II. To determine the incidence and severity of acute and chronic graft-versus-host disease (GVHD). III. To determine the rate of graft rejection and graft failure. IV. To determine the time to engraftment. V. To determine the incidence of serious adverse events with the addition of rituximab. VI. To evaluate the pharmacokinetics of rituximab in the setting of non-myeloablative allogeneic HCT. VII. To describe donor and host polymorphisms of the FC gamma receptor IIIa (FCg RIIIA) and CD32 and evaluate their impact on disease response and relapse. OUTLINE: Patients receive rituximab intravenously (IV), pre- and post-transplant, on days -3, 10, 24, and 38. Patients undergo donor peripheral blood stem cell transplant on day 0. Treatment continues in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up periodically for 18 months and then annually for 5 years.