Rituximab Versus Observation as Maintenance Therapy in Chronic Lymphocytic Leukemia (Chronic Lymphocytic Leukemia)

Inclusion Criteria: * B-CLL * Age \>18 * ECOG performance status 0-2 * Previous Rituximab containing induction treatment of the CLL in 1st or 2nd line * Patient must be in complete remission or partial remission after an induction treatment containing rituximab * ANC (absolute neutrophil count) \> 1,0 x 10e9 /L * Life expectancy \> 6 months * Patient´s written informed consent * Patient using a reliable means of contraception for the duration of the treatment including 2 months thereafter Exclusion Criteria: * Active uncontrolled bacterial, viral or fungal infection * Significantly reduced organ functions and bone marrow dysfunction not due to CLL * creatinine clearance of below 30mL/min * Patients with a history of other malignancies within 2 years prior to study entry * Patients with a history of severe cardiac disease * Other known comorbidity with the potential to dominate survival * Transformation to aggressive B-cell malignancy * Hypersensitivity with anaphylactic reaction to humanized monoclonal antibodies or any of the applied drugs * Medical condition requiring prolonged (\> 1 month) use of oral corticosteroids * Pregnant or breast feeding women * Any coexisting medical or psychological condition that would preclude participation in the study or compromise ability to give informed consent