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