Phase 2 Study to Assess Activity & Safety of Front-line Ibrutinib + Rituximab in Unfit Chronic Lymphocytic Leukemia

Given that: * Ibrutinib as single agent has been associated with a high response rate and PFS in previously treated patients, and in patients with poor prognosis clinical and biologic features. * Ibrutinib as single agent has proven activity and is associated with a good safety profile in elderly patients with CLL. * The Ibrutinib plus Rituximab combination has been associated with a high response rate and PFS in previously treated patients, and in patients with poor prognosis clinical and biologic features. * The combined administration of Ibrutinib and Rituximab could be an effective and safe front-line treatment schedule for unfit patients with CLL. * The current study is designed to evaluate whether first line treatment with Ibrutinib and Rituximab results in a significant improvement in PFS at 12 months as compared with chlorambucil plus rituximab in patients unfit for fludarabine- or bendamustine-based treatments.