Purine analog regimens for allogeneic transplant?

A clinical role for peripheral blood lymphocyte infusions and perspectives on collection

Molecular remissions were observed in some relapsed post allogeneic transplant chronic myeloid leukemia (CML) patients who received donor peripheral blood lymphocyte infusions (DLI). This was indirect evidence of immune-mediated tumor cell killing, and the process was termed graft-versus-leukemia (GVL). Mechanisms were hypothesized to be direct T cell mediated cell lysis or augmented programmed cell death. These observations formed the basis for exploring the role of DLI first in relapsed allogeneic transplant patients with other hematologic malignancies, then as prophylaxis for patients at high risk for relapse and then as adjunctive therapy for transplant strategies utilizing non-myeloablative conditioning regimens. Multiple clinical trials are underway to define dose, schedule, clinical and molecular response and laboratory assays to distinguish lymphocyte subsets mediating GVL and those responsible for graft-versus-host disease (GVHD) toxicity. This review outlines some of the donor/patient and therapy variables involved and some principles of mononuclear cell collection for cellular immunotherapy.

Infectious complications within the first year after nonmyeloablative allogeneic peripheral blood stem cell transplantation

Nonmyeloablative peripheral blood stem cell transplantation (PBSCT) is a novel therapeutic strategy for patients with malignant and non-malignant hematologic diseases. Infectious complications of this procedure have not been previously well described. Data on 12 patients transplanted at a tertiary care center were collected prospectively and verified retrospectively. Neutropenia developed in a third of patients, lasting for a median of 5 days. All patients developed some degree of graft-versus-host disease, as intended. Most patients achieved full chimerism by week 5. Bacterial infections occurred in two patients (17%). Cytomegalovirus (CMV) viremia occurred in five patients (42%) at a median of 80 days; none had received CMV prophylaxis. Viremia was associated with fever and fatigue in three patients, possible gastrointestinal involvement in one patient and was asymptomatic in one patient. All viremic patients responded to intravenous ganciclovir therapy. No fungal infections were documented. No patients died as a result of infection. The incidence of CMV viremia in our patients was high, but the incidence of invasive disease due to CMV was low. The best strategy to prevent CMV in patients undergoing nonmyeloablative PBSCT remains to be determined, but strategies employed in traditional allogeneic bone marrow transplantation should be considered in these patients.