Adverse events

Participants received ibrutinib 420 milligrams (mg) orally once daily for 3 cycles (each cycle is of 28 days) followed by the combination of ibrutinib 420 mg and venetoclax 400 mg orally once daily for 12 cycles (including a 5-week venetoclax dose ramp up starting in cycle 4). Participants who subsequently developed independent review committee (IRC)-confirmed progressive disease (PD) and had active disease requiring treatment were eligible to participate in the Subsequent Therapy Phase and received single-agent ibrutinib until disease progression or unacceptable toxicity.

Participants received chlorambucil 0.5 milligrams per kilogram (mg/kg) body weight orally once daily on Days 1 and 15 of Cycles 1 to 6 in combination with obinutuzumab 1000 mgs intravenously (IV) once daily on Days 1, 8, and 15 of Cycle 1 and Day 1 of Cycles 2 to 6 (each cycle is of 28 days). Participants who subsequently developed IRC-confirmed progressive disease (PD) and had active disease requiring treatment were eligible to participate in the Subsequent Therapy Phase and received single-agent ibrutinib until disease progression or unacceptable toxicity.