A Study to Assess the Effect of Maintenance Treatment With Rituximab Versus No Treatment in Participants With Progressive B-Cell Chronic Lymphocytic Leukemia (CLL)

PD occurred if any of the following events was observed: appearance of any new lesion, such as enlarged lymph nodes (greater than [>]1.5 centimeters [cm]), splenomegaly, hepatomegaly, or other organ infiltrates; an increase of greater than or equal to (>/=) 50 percent (%) in greatest determined diameter of any previous site; an increase in the previously noted enlargement of the liver or spleen by >/=50%; an increase in the number of blood lymphocytes by >/=50% with B-lymphocytes >/=5000 per microliter (/mcL); transformation to a more aggressive histology; occurrence of cytopenia (neutropenia, anemia, or thrombocytopenia) attributable to CLL.

PFS was defined as the time from date of randomization to date of PD, relapse, or death due to any cause. Participants alive with no evidence of PD or relapse were censored at date of last clinical examination. PD occurred if any of the following events was observed: appearance of any new lesion, such as enlarged lymph nodes (>1.5 cm), splenomegaly, hepatomegaly, or other organ infiltrates; an increase of >/=50% in greatest determined diameter of any previous site; an increase in the previously noted enlargement of the liver or spleen by >/=50%; an increase in the number of blood lymphocytes by >/=50% with B-lymphocytes >/=5000/mcL; transformation to a more aggressive histology; occurrence of cytopenia (neutropenia, anemia, or thrombocytopenia) attributable to CLL.

CR was achieved if participants met all of the following criteria >/= 2 months after last treatment: no lymphadenopathy (Ly)/ hepatomegaly/ splenomegaly/constitutional symptoms; neutrophils >1500/mcL, platelets (PL) >100,000/mcL, hemoglobin (Hb) >11.0 grams per deciliter (g/dL), bone marrow (BM) sample must be normocellular for age with lymphocytes <30% of nucleated cells. PR: a reduction in Ly (decrease in lymph node size by >/=50% compared to pre-treatment state, no increase in any lymph node, no new enlarged lymph node); a reduction of >/=50% from pre-treatment state in the lymphocytes count, and in enlargement of the spleen or liver; any one of the following: neutrophils >1500/mcL, PL >100,000/mcL (or 50% improvement from baseline), Hb >11.0 g/dL (or 50% improvement from baseline).

MRD was defined by the presence of tumor cells in bone marrow, using 4-color flow cytometry of cluster of differentiation (CD)19/CD5/CD20/CD79b. MRD was assessed in participants who achieved CR or PR. CR: if participants met all of the following criteria >/=2 months after last treatment: no Ly/ hepatomegaly/ splenomegaly/constitutional symptoms; neutrophils >1500/mcL, PL >100,000/mcL, Hb >11.0 g/dL, BM sample must be normocellular for age with lymphocytes <30% of nucleated cells. PR: a reduction in Ly; a reduction of >/=50% from pre-treatment state in the lymphocytes count, and in enlargement of the spleen or liver; any one of the following: neutrophils >1500/mcL, PL >100,000/mcL (or 50% improvement from baseline), Hb >11.0 g/dL (or 50% improvement from baseline).

PFS: time from date of randomization to date of PD, relapse, or death from any cause. Participants alive with no evidence of PD or relapse were censored at date of last clinical examination. PD: appearance of any new lesion, such as enlarged lymph nodes (>1.5 cm), splenomegaly, hepatomegaly, or other organ infiltrates; an increase of >/=50% in greatest determined diameter of any previous site; an increase in previously noted enlargement of liver or spleen by >/=50%; an increase in number of blood lymphocytes by >/=50% with B-lymphocytes >/=5000/mcL; transformation to a more aggressive histology; or occurrence of cytopenia attributable to CLL. Rai Stage: staging for CLL, based on lymphocyte, red blood cell and platelet counts and size of lymph nodes, spleen, and liver. Rai Stage I or II are intermediate risk CLL and Rai Stage III or IV are high risk CLL. This outcome measure assessed relationship between clinical markers and clinical outcome (PFS) after study treatment.

CR was achieved if participants met all of the following criteria >/= 2 months after last treatment: no Ly/ hepatomegaly/ splenomegaly/constitutional symptoms; neutrophils >1500/mcL, PL >100,000/mcL, Hb >11.0 g/dL, BM sample must be normocellular for age with lymphocytes <30% of nucleated cells. PR: a reduction in Ly; a reduction of >/=50% from pre-treatment state in the lymphocytes count, and in enlargement of the spleen or liver; any one of the following: neutrophils >1500/mcL, PL >100,000/mcL (or 50% improvement from baseline), Hb >11.0 g/dL (or 50% improvement from baseline). Rai Stage: staging for CLL, based on lymphocyte, red blood cell and platelet counts and size of lymph nodes, spleen, and liver. Rai Stage I or II are intermediate risk CLL and Rai Stage III or IV are high risk CLL. This outcome measure assessed the relationship between clinical markers and clinical outcome (response) after study treatment.

CR was achieved if participants met all of the following criteria >/=2 months after last treatment: no Ly/ hepatomegaly/ splenomegaly/constitutional symptoms; neutrophils >1500/mcL, PL >100,000/mcL, Hb >11.0 g/dL, BM sample must be normocellular for age with lymphocytes <30% of nucleated cells. PR: a reduction in Ly; a reduction of >/=50% from pre-treatment state in the lymphocytes count, and in enlargement of the spleen or liver; any one of the following: neutrophils >1500/mcL, PL >100,000/mcL (or 50% improvement from baseline), Hb >11.0 g/dL (or 50% improvement from baseline). Rai Stage: staging for CLL, based on lymphocyte, red blood cell and platelet counts and size of lymph nodes, spleen, and liver. Rai Stage I or II are intermediate risk CLL and Rai Stage III or IV are high risk CLL. This outcome measure assessed the relationship between clinical markers and clinical outcome (response) after study treatment.

MRD: the presence of tumor cells in bone marrow, using 4-color flow cytometry of CD19/CD5/CD20/CD79b. MRD was assessed in participants who achieved CR or PR. CR (>/=2 months after last treatment): no Ly/ hepatomegaly/ splenomegaly/constitutional symptoms; neutrophils >1500/mcL, PL >100,000/mcL, Hb >11.0 g/dL, BM sample must be normocellular for age with lymphocytes <30% of nucleated cells. PR: a reduction in Ly; a reduction of >/=50% from pre-treatment state in the lymphocytes count, and in enlargement of the spleen or liver; any one of the following: neutrophils >1500/mcL, PL >100,000/mcL (or 50% improvement from baseline), Hb >11.0 g/dL (or 50% improvement from baseline). Rai Stage: staging for CLL, based on lymphocyte, red blood cell and platelet counts and size of lymph nodes, spleen, and liver. Rai Stage I or II are intermediate risk CLL and Rai Stage III or IV are high risk CLL. This outcome measure assessed relationship between clinical markers and MRD after study treatment.

MRD: the presence of tumor cells in bone marrow, using 4-color flow cytometry of CD19/CD5/CD20/CD79b. MRD was assessed in participants who achieved CR or PR. CR (>/=2 months after last treatment): no Ly/ hepatomegaly/ splenomegaly/constitutional symptoms; neutrophils >1500/mcL, PL >100,000/mcL, Hb >11.0 g/dL, BM sample must be normocellular for age with lymphocytes <30% of nucleated cells. PR: a reduction in Ly; a reduction of >/=50% from pre-treatment state in the lymphocytes count, and in enlargement of the spleen or liver; any one of the following: neutrophils >1500/mcL, PL >100,000/mcL (or 50% improvement from baseline), Hb >11.0 g/dL (or 50% improvement from baseline). Rai Stage: staging for CLL, based on lymphocyte, red blood cell and platelet counts and size of lymph nodes, spleen, and liver. Rai Stage I or II are intermediate risk CLL and Rai Stage III or IV are high risk CLL. This outcome measure assessed relationship between clinical markers and MRD after study treatment.