A Study of MabThera (Rituximab) Plus Chlorambucil in Participants With Chronic Lymphocytic Leukemia.

An Open-Label Study to Characterize the Safety and Response Rate of MabThera (Rituximab) Plus Chlorambucil in Previously Untreated Patients With CD20-Positive B-Cell Chronic Lymphocytic Leukemia

This single arm study will assess the safety and effect on response rate of a combination of rituximab and chlorambucil in previously untreated participants with B-cell chronic lymphocytic leukemia. Participants will receive 6 monthly cycles of combination treatment, followed by up to 6 cycles of chlorambucil alone. Rituximab will be administered on Day 1 of each cycle, at a dose of 375 milligrams per square meter (mg/m^2) intravenously (IV) in Cycle 1, and 500 mg/m^2 in subsequent cycles, and chlorambucil will be administered on Days 1-7 of each cycle at a dose of 10 mg/m^2/day per oral (PO).

Inclusion Criteria:

• previously untreated participants with cluster of differentiation 20 (CD20) positive B-cell chronic lymphocytic leukemia;
• participants with progressive Binet stage B, or C requiring therapy according to National Cancer Institute (NCI) criteria;
• Eastern Cooperative Oncology Group (ECOG) performance status <=2.

Exclusion Criteria:

• previous treatment for Chronic Lymphocytic Leukaemia (CLL);
• known concomitant hematological malignancy;
• transformation to aggressive B-cell malignancy;
• history of severe cardiac disease;
• known hypersensitivity or anaphylactic reactions to murine antibodies.