You may continue taking the study drug combination of rituximab and Ibrutinib for up to 6 cycles, after which Ibrutinib will be continued for up to a total of 12 cycles. It will be possible to continue with Ibrutinib treatment beyond 12 cycles if the study doctor thinks it is in your best interest. You will no longer be able to take the study drug if the disease gets worse, if intolerable side effects occur, or if you are unable to follow study directions.