Unmanipulated peripheral blood stem cell autograft in chronic lymphocytic leukemia: clinical findings and biological monitoring

BACKGROUND AND OBJECTIVES: To investigate the feasibility of peripheral blood stem cell (PBSC) transplantion in patients with high-risk chronic lymphocytic leukemia (CLL) in remission after fludarabine therapy, the clinical impact of minimal residual disease (MRD) monitoring and the immunologic reconstitution after transplantation. DESIGN AND METHODS: Twenty CLL patients, in clinical complete remission (CR) after fludarabine, were offered an unmanipulated PBSC transplant and were longitudinally monitored for MRD and immunologic reconstitution. RESULTS: Due to unsatisfactory PBSC collection, 4 patients received bone marrow cells. All patients engrafted. Two patients died, one due to infection and one because of another neoplasia. Thirteen patients are at present in clinical CR after a median follow-up of 17 months and 18 patients are alive with a survival probability of 0.87 (+/-0.04) at 52 months after transplant. Fifteen patients had a molecular remission. Three of them showed a molecular relapse 16-28 months after autograft, followed by a clinical relapse 10-16 months later. Three of the four patients who remained persistently rearranged could be revaluated over time and showed an immunologic relapse 11-26 months after transplant; two of these had a clinical relapse 12 and 7 months later. A marked and persistent impairment of both the B- and T-immunologic compartments was recorded in the horizontal follow-up. INTERPRETATION AND CONCLUSIONS: Unmanipulated PBSC autograft is a feasible procedure that produces prolonged molecular remissions in high-risk CLL patients. Persistence or reappearance of a molecular signal after engraftment is predictive of subsequent immunologic and clinical CLL recurrence. The long -lasting impairment of the host immune repertoire after fludarabine followed by autograft has to be taken into account in the patients' management