A Safety and Efficacy Study of Ibrutinib in Pediatric and Young Adult Participants With Relapsed or Refractory Mature B-cell Non-Hodgkin Lymphoma

Inclusion Criteria:

   - Participants with 1 to less than (<) 18 years of age (Part 1 only), or 1 to 30 years
   of age, inclusive, if initial diagnosis of mature B-cell non-Hodgkin lymphoma (NHL)
   occurred at <18 years of age (Part 2 only)

   - Participants must be in first recurrence and have received only one prior line of
   therapy or have disease that is primarily refractory to conventional therapy

   - Participants must have at least 1 of the following: 1 site of measurable disease
   greater than (>) 1 centimeter (cm) in the longest diameter and >1 cm in the shortest
   diameter by radiological imaging; bone marrow involvement; cerebrospinal fluid with
   blasts present

   - Participants with lansky-Karnofsky score of greater than or equal to (>=) 50

   - Adolescent women/young women of childbearing potential must have a negative highly
   sensitive serum or urine beta-human chorionic gonadotropin (beta-hCG) pregnancy test
   at Screening before enrollment/randomization. Adolescent/young women who are pregnant
   or breastfeeding are ineligible for this study

Exclusion Criteria:

   - Participants with ongoing anticoagulation treatment with warfarin or equivalent
   vitamin K antagonists (example phenprocoumon), or ongoing treatment with agents known
   to be strong CYP3A4/5 inhibitors, or has taken any disallowed therapies as noted in
   Section 8.2, Prohibited Medications, before the planned first dose of study drug

   - Participants with inherited or acquired bleeding disorders

   - Participants with clinically significant arrhythmias, complex congenital heart
   disease, or left ventricular ejection fraction (LVEF) <50 percent (%) or shortening
   fraction (SF) <=28%

   - Participants with known history of human immunodeficiency virus (HIV) or active
   Hepatitis B or C virus

   - Participants with any condition that could interfere with the absorption or metabolism
   of ibrutinib including malabsorption syndrome, disease significantly affecting
   gastrointestinal function, or resection of the stomach or small bowel

   - Participants with known allergies, hypersensitivity, or intolerance to ibrutinib or
   its excipients (refer to Investigator's Brochure)

   - A diagnosis of post-transplant lymphoproliferative disease (PTLD)

   - Participants who are within 6 months of an allogeneic bone marrow transplant

   - Participants who have had prior exposure to ibrutinib