Evaluation of minimal residual disease in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a malignancy with a variable prognosis. Poor-risk cases are characterized by advanced clinical stage, short lymphocyte doubling time, unmutated immunoglobulin heavy gene (IgVH) status, distinct genomic aberrations, ZAP70 and CD38 expression and elevated serum thymidine kinase levels. During the last decade, effective chemotherapy combinations have been developed, making high complete remission rates in this disease feasible. However, after conventional chemotherapy and autologous stem cell transplantation (SCT), all patients will eventually relapse. Nevertheless, time to progression is highly variable in patients who achieve complete clinical remissions. Therefore, minimal residual disease (MRD) undetectable by clinical means must have been present in all of these cases.