Inclusion Criteria:

   - 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

Exclusion Criteria:

   - Requires anticoagulation with warfarin or equivalent vitamin K antagonists

   - Requires treatment with strong cytochrome P450 (CYP)3A4/5 inhibitors, unless
   previously approved by sponsor

   - Any condition or situation which, in the opinion of the investigator, may put the
   participant at significant risk, may confound the study results, or may interfere
   significantly with volunteer's participation in the study