16. Positive serology for Hepatitis B (HB) defined as a positive test for HBsAg. . Patients with prior history of Hepatitis B infection, but immune, with only IgG Hepatitis core antibody + (HBcAb +) must be checked for hepatitis B virus titers by PCR and if the viral load is undetectable may be enrolled. These patients must receive anti-viral prophylaxis, such as lamivudine 100 mg po daily (or an equivalent) starting at least one week prior to cycle 1 and continued through the completion of treatment and for 9 months after the last dose of ofatumumab. Hepatitis B virus titers by quantitative PCR and HBsAg should be checked every month (+/- 1 week) while on therapy and every 3 months (+/- 1 month) thereafter for 9 months after the last ofatumumab dose. In the event of an early termination of the clinical trial for any reason, a treating physician will be determining the frequency and the length of follow up studies of hepatitis B virus titers and HBsAg status. It is recommended that the patient remains on prophylactic lamivudine or an equivalent, as above, regardless of whether the study was continued or terminated. In addition, if appropriate consultation with a hepatologist should be obtained.