• Participants must be currently participating in an ibrutinib clinical study considered complete and have received at least 6 months of treatment with ibrutinib. At study entry, participants must be actively receiving treatment with single-agent ibrutinib; or participants must have participated in an ibrutinib randomized clinical study in which they initially received comparator treatment and now cross-over to ibrutinib. Note: A minimum of 6 months requirement for prior ibrutinib treatment will not be mandatory in this case and participants with less than 6 months will be required to have more frequent initial safety assessments; or participants must be currently participating in study PCI-32765LYM1002. At study entry, participants must be actively receiving combination treatment with ibrutinib and nivolumab or single-agent ibrutinib

• Investigator's assessment that the benefit of continued ibrutinib therapy as a single agent or in combination with nivolumab will outweigh the risks

• Agrees to protocol-defined use of effective contraception

• Negative blood or urine pregnancy test at screening