Patients receive a run-up course of ibrutinib orally (PO) daily on days 1-28. Patients then receive ibrutinib PO and lenalidomide PO daily on days 1-28. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. After 12 courses, patients who have achieved complete remission (CR)/CR with incomplete marrow recovery (CRi), nodular partial remission (PR), partial remission or who have stable disease discontinue lenalidomide and continue ibrutinib.