Investigator-assessed PFS. (A) PFS with single-agent ibrutinib vs chlorambucil in first-line CLL/SLL in the intent-to-treat population. PFS by (B) del(11q) status and (C) IGHV mutational status. Survival analyses are from randomization until event or censoring at last evidence of non-PD; vertical tick marks indicate censored patients. NE, not estimable; NR, not reached.