Part 2: Number of Participants With CD79B, CARD11, and MYD Mutations

Part 2: Ibrutinib+CIT (RICE or RVICI)

Participants received ibrutinib based on age group and BSA in combination with CIT (investigator choice of RICE or RVICI) until 3 treatment cycles, transplantation if indicated, or until progressive disease (PD) or unacceptable toxicity. For both regimens, triple intrathecal therapy consisting of methotrexate, corticosteroid, and cytarabine will be administered for central nervous system (CNS) prophylaxis in age-appropriate dosing. Participants of age groups 1-5 years and 6-11 years received ibrutinib 440 mg/m\^2, and age group 12-17 years received Ibrutinib 329 mg/m\^2 (dose selected from Part 1).

Part 2: Chemoimmunotherapy

Participants received CIT (investigator choice of RICE or RVICI) alone based on age group and BSA until 3 treatment cycles, transplantation if indicated, or until PD or unacceptable toxicity. For both regimens, triple intrathecal therapy consisting of methotrexate, corticosteroid, and cytarabine will be administered for CNS prophylaxis in age-appropriate dosing. The RICE regimen was composed of rituximab 750 mg/m\^2, ifosfamide 9 g/m2, carboplatin 635 mg/m\^2, etoposide 300 mg/m\^2, and dexamethasone 100 mg/m\^2. The RVICI regimen was composed of rituximab 750 mg/m\^2, vincristine 1.6 mg/m\^2, idarubicin 20 mg/m\^2, carboplatin 800 mg/m\^2, ifosfamide 10 g/m\^2, and dexamethasone 100 mg/m\^2 (all doses represented as cumulative administered in 1 cycle).

Analysis denominator · Participants