PFS is defined as the time from randomization until progression/death. Per the IRC, if the participant had progression between scheduled visits, died before the first assessment, or died between adequate visits, the endpoint was considered progressed. If there was no progression at the end of the trial, treatment discontinuation for undocumented progression, treatment discontinuation for toxicity/other reason, new anti-cancer treatment, and death/progression after 2 or more missed visits in a row, the endpoint was censored. Clinical progression is not considered as progression endpoint.

Time to next chronic lymphocytic leukemia (CLL) treatment is defined as the time from treatment allocation/randomization (Visit 2) until the time of the first administration of the next CLL treatment other than ofatumumab (or HuMaxCD20, a fully human monoclonal antibody to CD20 that is expressed on the surface of B-cells).

OS is defined as the time from allocation to death. OS will also be subgrouped for responders and non-responders.

The peripheral blood for each participant was collected and analyzed for CD5+CD19+ cell counts. CD is "cluster of differentiation," is a cell surface marker for immunophenotyping, and, in this case, is a surrogate for B cell malignancy (indicates malignant B cells). Percent change from Visit 2 (Week 0, Baseline) = (value at Week 7 minus value at Week 0 divided by value at Week 0) x 100.

The peripheral blood for each participant was collected and analyzed for CD5+CD20+ cell counts. CD is "cluster of differentiation," is a cell surface marker for immunophenotyping, and, in this case, is a surrogate for B cell malignancy (indicates malignant B cells). Percent change from Visit 2 (Week 0, Baseline) = (value at Week 7 minus value at Week 0 divided by value at Week 0) x 100.

Tumor size and change in tumor size will be measured by the absolute value of and the percent change in the sum of products of the diameters of the largest abnormal lymph nodes from Baseline to Week 24 (Visit 14). Percent change from Visit 2 (Baseline, Week 0) = (value at Week 24 minus value at Week 0 divided by value at Week 0) x 100.

Participants with complete resolution of constitutional symptoms were those in whom no constitutional symptoms, such as night sweats, weight loss, and fever or extreme fatigue, were observed.

Participants with complete resolution of lymphadenopathy (disease involving the lymph nodes) were defined as those in whom all observed lymph nodes were of normal size (all nodes <1 centimeters) as determined by physical examination assessed by the investigator. All palpable lymph node sizes were recorded.

ECOG performance status is a measure of the participant's ability to carry out activities of daily living on 6-point scale (0=fully active, 1=restricted in physically activity, ambulatory, 2=ambulatory [>50% of waking hours], 3=capable of only limited self care, 4=completely disabled, 5=Dead). Improvement in ECOG performance status is defined as a decrease from baseline by at least one score on the ECOG scale.

The number of participants (par.) who were positive, negative, or had missing data for the following prognostic factors indicative of altered responsiveness to treatment and/or survival was measured: 17p-, 11q-, +12q, 6q-, 13q-. Par. were assessed by FISH for these chromosomal abnormalities known tobe prognostic for time to treatment and survival when detected at diagnosis. Par. were categorized by the chromosomal abnormality detected: 17 p deletion, 11q deletion (but not 17 p deletion), 12 q trisomy (but not 17 p or 111q deletion), 13q deletion only, and no chromosomal abnormalities found.

The number of participants (par.) who had improvement in hemoglobin levels >=11 grams (g)/deciliter (dl) (6.8 millimoles/liter) or 50% improvement over baseline was measured.

Improvement in thromb. is defined as a decrease from Visit 2 by >=1 National Cancer Institute Common Terminology Criteria (NCI CTC) grade. Thromb. is defined as low platelet counts resulting from refractory CLL, damage from prior treatment, advanced age, or reduced bone marrow function and can be considered as an adverse condition. Adverse events (AEs) such as thromb. in a cancer indication are graded on a scale determined by the NCI called the NCI CTC: lowest, grade 1; highest, grade 5 (death). Changes in this grading can assess improvements or declines in the severity of the AE.

Participants with complete resolution of enlarged liver (hepatomegaly) were defined as those with an enlarged palpable liver at baseline followed by the absence of hepatomegaly post- baseline (i.e., the liver was of normal size). Liver size was assessed by physical examination and documented as "centimeters" under the costal margin with relative changes in spleen size in 1 dimension calculated based on palpated numeric measurements (as per the 1996 NCIWG guidelines).

Low levels of neutrophils (neutropenia) may increase the risk of developing serious infections and may be considered an adverse condition and evaluated on the NCI CTC with a grade. Improvement in neutropenia is defined as a decrease from Visit 2 (baseline) by at least one NCI CTC grade. Improvement is defined as a decrease from Visit 2 by at least one NCI CTC grade.

Participants with complete resolution of enlarged spleen (splenomegaly) were defined as those with an enlarged palpable spleen at baseline followed by the absence of splenomegaly post-baseline (i.e., the spleen was of normal size). Spleen size was assessed by physical examination and documented as "centimeters" under the costal margin with relative changes in spleen size in 1 dimension calculated based on palpated numeric measurements (as per the 1996 NCIWG guidelines).

An adverse event (AE) was defined as any untoward medical occurrence in a participant administered a pharmaceutical product and which did not necessarily have a causal relationship with the treatment. A list of AEs experienced in the study with a frequency threshold of 5% can be found in the AE section of this results record.

Cmax is defined as the maximum concentration of drug in serum samples. Ctrough is defined as the trough serum concentration (measured concentration at the end of a dosing interval [taken directly before the next administration]). No drug was present before the first infusion; therefore, there are no Ctrough results for Dose 1

AUC is defined as the area under the ofatumumab concentration-time curve as a measure of drug exposure. AUC(0-inf) is AUC from the start of infusion extrapolated to infinity. AUC(0-tau) is AUC from the start of infusion over the dosing interval.

Half-life ( t1/2) is defined as the terminal half-life and is the time required for the amount of drug in the body to decrease by half.

CL is the clearance of drug from serum, which is defined as the volume of serum from which the drug is cleared per unit time.

Vss is defined as the volume of distribution at steady state of ofatumumab.

Ofatumumab iv infusion was initiated at 300 mg, followed by seven weekly 2000 mg infusions and then four monthly infusions of 2000 mg for a duration of 24 weeks. The IRC classified these participants as "other,"defined as participants who were enrolled in the study but did not meet criteria for DR or BFR.

Total of all reporting groups

Duration of response is defined as the time from the initial response (first visit at which response is observed) to progression or death. If the participant had progression between scheduled visits, no progression at the end of the trial, treatment discontinuation for undocumented progression, treatment discontinuation for toxicity or other reason, new anti-cancer treatment, and experienced death or progression after two or more missed visits in a row the endpoint was censored.

FAS

PFS is defined as the time from randomization until progression/death. Per the IRC, if the participant had progression between scheduled visits, died before the first assessment, or died between adequate visits, the endpoint was considered progressed. If there was no progression at the end of the trial, treatment discontinuation for undocumented progression, treatment discontinuation for toxicity/other reason, new anti-cancer treatment, and death/progression after 2 or more missed visits in a row, the endpoint was censored. Clinical progression is not considered as progression endpoint.

FAS

Time to next chronic lymphocytic leukemia (CLL) treatment is defined as the time from treatment allocation/randomization (Visit 2) until the time of the first administration of the next CLL treatment other than ofatumumab (or HuMaxCD20, a fully human monoclonal antibody to CD20 that is expressed on the surface of B-cells).

FAS

OS is defined as the time from allocation to death. OS will also be subgrouped for responders and non-responders.

FAS

The peripheral blood for each participant was collected and analyzed for CD5+CD19+ cell counts. CD is "cluster of differentiation," is a cell surface marker for immunophenotyping, and, in this case, is a surrogate for B cell malignancy (indicates malignant B cells). Percent change from Visit 2 (Week 0, Baseline) = (value at Week 7 minus value at Week 0 divided by value at Week 0) x 100.

FAS

The peripheral blood for each participant was collected and analyzed for CD5+CD20+ cell counts. CD is "cluster of differentiation," is a cell surface marker for immunophenotyping, and, in this case, is a surrogate for B cell malignancy (indicates malignant B cells). Percent change from Visit 2 (Week 0, Baseline) = (value at Week 7 minus value at Week 0 divided by value at Week 0) x 100.

FAS

Tumor size and change in tumor size will be measured by the absolute value of and the percent change in the sum of products of the diameters of the largest abnormal lymph nodes from Baseline to Week 24 (Visit 14). Percent change from Visit 2 (Baseline, Week 0) = (value at Week 24 minus value at Week 0 divided by value at Week 0) x 100.

FAS

Participants with complete resolution of constitutional symptoms were those in whom no constitutional symptoms, such as night sweats, weight loss, and fever or extreme fatigue, were observed.

FAS. Data were provided for the number of participants with constitutional symptoms at baseline attending each visit. Participants withdrawn during the study were not analyzed. (Participants without baseline constitutional symptoms did not experience new constitutional symptoms during the trial period.)

Participants with complete resolution of lymphadenopathy (disease involving the lymph nodes) were defined as those in whom all observed lymph nodes were of normal size (all nodes <1 centimeters) as determined by physical examination assessed by the investigator. All palpable lymph node sizes were recorded.

FAS. Data were provided for the number of participants with lymphadenopathy at baseline attending each visit. Participants withdrawn during the study were not analyzed. (Participants without baseline lymphadenopathy remained free of lymphadenopathy during the trial.)

ECOG performance status is a measure of the participant's ability to carry out activities of daily living on 6-point scale (0=fully active, 1=restricted in physically activity, ambulatory, 2=ambulatory [>50% of waking hours], 3=capable of only limited self care, 4=completely disabled, 5=Dead). Improvement in ECOG performance status is defined as a decrease from baseline by at least one score on the ECOG scale.

FAS. Data were provided for participants (par.) with an ECOG score >0 at baseline attending each visit. Par. withdrawn from the study were not analyzed. (55 par. had an ECOG performance status of 0 at baseline and therefore did not have the opportunity to improve. No par. with an ECOG score of 0 at baseline worsened during the trial.)

The number of participants (par.) who were positive, negative, or had missing data for the following prognostic factors indicative of altered responsiveness to treatment and/or survival was measured: 17p-, 11q-, +12q, 6q-, 13q-. Par. were assessed by FISH for these chromosomal abnormalities known tobe prognostic for time to treatment and survival when detected at diagnosis. Par. were categorized by the chromosomal abnormality detected: 17 p deletion, 11q deletion (but not 17 p deletion), 12 q trisomy (but not 17 p or 111q deletion), 13q deletion only, and no chromosomal abnormalities found.

FAS. Par. were categorized hierarchically (by severity of abnormality): par. with a 17 p deletion (D); par. with an 11q D, but not a 17 p D; par. with 12q trisomy, but not a 17p or 11q D; par. with no aberrations found; par. with a 13q D as the sole aberration; and par. with 6q D (and not any of the above categories). Some par. had missing data.

The number of participants (par.) who had improvement in hemoglobin levels >=11 grams (g)/deciliter (dl) (6.8 millimoles/liter) or 50% improvement over baseline was measured.

FAS. Par. were excluded from analysis if they received treatment of red blood cells (RBCs), received transfusions or a RBC growth factor (erythropoietin), died, withdrew from the trial, or began next CLL treatment. Only those par. remaining in the study at Week 28 were analyzed. No par. in the "Other" treatment arm met the criteria for analysis.

Improvement in thromb. is defined as a decrease from Visit 2 by >=1 National Cancer Institute Common Terminology Criteria (NCI CTC) grade. Thromb. is defined as low platelet counts resulting from refractory CLL, damage from prior treatment, advanced age, or reduced bone marrow function and can be considered as an adverse condition. Adverse events (AEs) such as thromb. in a cancer indication are graded on a scale determined by the NCI called the NCI CTC: lowest, grade 1; highest, grade 5 (death). Changes in this grading can assess improvements or declines in the severity of the AE.

FAS. Only those participants remaining in the study at Week 28 were analyzed. No par. in the "Other" treatment arm met the criteria for analysis.

Participants with complete resolution of enlarged liver (hepatomegaly) were defined as those with an enlarged palpable liver at baseline followed by the absence of hepatomegaly post- baseline (i.e., the liver was of normal size). Liver size was assessed by physical examination and documented as "centimeters" under the costal margin with relative changes in spleen size in 1 dimension calculated based on palpated numeric measurements (as per the 1996 NCIWG guidelines).

FAS. Data were provided for the number of participants with hepatomegaly from baseline attending each visit. Participants withdrawn during the study were not analyzed. Only participants with baseline hepatomegaly and a post-baseline assessment are included.

Low levels of neutrophils (neutropenia) may increase the risk of developing serious infections and may be considered an adverse condition and evaluated on the NCI CTC with a grade. Improvement in neutropenia is defined as a decrease from Visit 2 (baseline) by at least one NCI CTC grade. Improvement is defined as a decrease from Visit 2 by at least one NCI CTC grade.

FAS. Only those par. remaining in the study at Week 28 were analyzed. No par. in the "Other" treatment arm met the criteria for analysis.

Participants with complete resolution of enlarged spleen (splenomegaly) were defined as those with an enlarged palpable spleen at baseline followed by the absence of splenomegaly post-baseline (i.e., the spleen was of normal size). Spleen size was assessed by physical examination and documented as "centimeters" under the costal margin with relative changes in spleen size in 1 dimension calculated based on palpated numeric measurements (as per the 1996 NCIWG guidelines).

FAS. Data were provided for the number of participants with splenomegaly at baseline attending each visit. Participants withdrawn during the study were not analyzed. Only participants with baseline splenomegaly and a post-baseline assessment are included.

An adverse event (AE) was defined as any untoward medical occurrence in a participant administered a pharmaceutical product and which did not necessarily have a causal relationship with the treatment. A list of AEs experienced in the study with a frequency threshold of 5% can be found in the AE section of this results record.

FAS

Cmax is defined as the maximum concentration of drug in serum samples. Ctrough is defined as the trough serum concentration (measured concentration at the end of a dosing interval [taken directly before the next administration]). No drug was present before the first infusion; therefore, there are no Ctrough results for Dose 1

FAS. Data were provided for the number of participants attending each visit. Participants withdrawn during the study were not analyzed.

AUC is defined as the area under the ofatumumab concentration-time curve as a measure of drug exposure. AUC(0-inf) is AUC from the start of infusion extrapolated to infinity. AUC(0-tau) is AUC from the start of infusion over the dosing interval.

FAS. Data were provided for the number of participants attending each visit for whom the parameter could be calculated. Participants withdrawn during the study were not analyzed.

Half-life ( t1/2) is defined as the terminal half-life and is the time required for the amount of drug in the body to decrease by half.

FAS. Data were provided for the number of participants attending each visit for whom the parameter could be calculated. Participants withdrawn during the study were not analyzed.

CL is the clearance of drug from serum, which is defined as the volume of serum from which the drug is cleared per unit time.

FAS. Data were provided for the number of participants attending each visit for whom the parameter could be calculated. Participants withdrawn during the study were not analyzed.

Vss is defined as the volume of distribution at steady state of ofatumumab.

FAS. Data were provided for the number of participants attending each visit for whom the parameter could be calculated. Participants withdrawn during the study were not analyzed.

Ofatumumab iv infusion was initiated at 300 mg, followed by seven weekly 2000 mg infusions and then four monthly infusions of 2000 mg for a duration of 24 weeks. The IRC classified these participants as BFR, defined as participants who were enrolled in the study and were refractory to fludarabine with bulky lymphadenopathy.

Ofatumumab iv infusion was initiated at 300 mg, followed by seven weekly 2000 mg infusions and then four monthly infusions of 2000 mg for a duration of 24 weeks. The IRC classified these participants as "other,"defined as participants who were enrolled in the study but did not meet criteria for DR or BFR.