Transplant in chronic lymphocytic leukemia: to do it or not and if so, when and how?

Abstract

Most patients with chronic lymphocytic leukemia (CLL) have an indolent clinical course, but the disease remains incurable with standard therapy and the prognosis is dismal for those patients with disease refractory to available treatment options. The only potentially curative treatment is allogeneic hematopoietic stem cell transplantation (SCT), but since CLL is a disease of elderly patients, few patients are candidates for myeloablative allogeneic SCT. Although autologous SCT is feasible and has low treatment-related mortality, it is not curative. The widespread adoption of reduced-intensity conditioning (RIC) allogeneic SCT has made this approach applicable to the elderly patient population with CLL. This approach relies on the documented graft-versus-leukemia (GVL) effect and is strong in CLL. Steps to further decrease the morbidity and mortality of the RIC SCT and in particular to reduce the incidence of chronic extensive graft-versus-host disease (GVHD) remain a major focus. Many potential treatments are available for CLL, and appropriate patient selection and SCT timing remain controversial and the focus of ongoing clinical trials. The use of SCT must always be weighed against the risk of the underlying disease, particularly in a setting where improvements in treatment are leading to improved outcome. The major challenge remains how to identify which patients with CLL merit this approach and where in the treatment course this treatment can be applied optimally.