A Phase 3 Study of Ibrutinib (PCI-32765) Versus Ofatumumab in Patients With Relapsed or Refractory Chronic Lymphocytic Leukemia

* ECOG performance status of 0-1. * Diagnosis of CLL or SLL that meets IWCLL 2008 criteria. * Active disease meeting at least 1 of the IWCLL 2008 criteria for requiring treatment. * Must have received at least one prior therapy for CLL/SLL. * Considered not appropriate for treatment or retreatment with purine analog based therapy. * Measurable nodal disease by CT. * Patients must be able to receive outpatient treatment and laboratory monitoring at the institution that administers study drug for the entire study.

* Known CNS lymphoma or leukemia. * No documentation of cytogenetic and/or FISH in patient records prior to first dose of study drug. * Any history of Richter's transformation or prolymphocytic leukemia. * Uncontrolled Autoimmune Hemolytic Anemia (AIHA) or idiopathic thrombocytopenia purpura (ITP). * Prior exposure to ofatumumab or to ibrutinib. * Prior autologous transplant within 6 months prior to first dose of study drug. * Prior allogeneic stem cell transplant within 6 months or with any evidence of active graft versus host disease or requirement for immunosuppressants within 28 days prior to first dose of study drug. * History of prior malignancy, with the exception of certain skin cancers and malignancies treated with curative intent and with no evidence of active disease for more than 3 years. * Serologic status reflecting active hepatitis B or C infection. * Unable to swallow capsules or disease significantly affecting gastrointestinal function. * Uncontrolled active systemic fungal, bacterial, viral, or other infection. * History of stroke or intracranial hemorrhage within 6 months prior to the first dose of study drug. * Requires anticoagulation with warfarin.