Rituximab anti-CD20 monoclonal antibody induces marked but transient reductions of peripheral blood lymphocytes in chronic lymphocytic leukaemia patients

Rituximab has been recently proposed as an effective non-chemotherapeutic o ption for patients with follicle centre lymphoma (FCL). However, less is kn own on its role in chronic lymphocytic leukaemia (CLL). We thus decided to assess its effectiveness on a panel of 7 patients with refractory or relaps ed CLL. Mild (5 patients) or severe (1 patient) adverse reactions were obse rved during the first hours of Rituximab infusion, almost exclusively at th e first course. Symptoms rapidly subsided with temporary drug withdrawal an d low dose steroids. All patients could receive the whole scheduled treatme nt. A striking reduction of peripheral blood (PB) lymphocyte counts was obs erved in all patients (median 93%; range 57-99%). However, Rituximab was po orly effective towards nodal and splenic disease. Patients required additio nal treatment after a median time of 70 d (range: 20-180 d). Our data show that Rituximab delivery in CLL patients is feasible and has an acceptable t oxicity, although it probably does not represent an ideal treatment option when delivered using schedules originally designed for FCL patients. Howeve r, responses observed at PB level suggest that Rituximab has an activity wh ich is not negligible and deserves further investigation in CLL. Future app roaches will be directed to the development of alternative schedules which may include dose intensification, combination of Rituximab and chemotherapy , and in vivo purging of peripheral blood progenitor cell harvests for auto grafting procedures.