Ibrutinib in Treating Participants With Untreated High Risk Smoldering Mantle Cell Lymphoma

PRIMARY OBJECTIVE: I. To measure the progression-free survival (PFS) in previously untreated high-risk smoldering mental cell lymphoma (MCL) patients treated with ibrutinib. SECONDARY OBJECTIVES: I. To evaluate the safety of ibrutinib in previously untreated high risk smoldering MCL. II. To evaluate the response rate and duration of response of ibrutinib. III. To study clonal evolution in MCL while under ibrutinib. EXPLORATORY OBJECTIVES: I. To collect serial samples for our correlative study (plasma, peripheral blood mononuclear cells \[PBMC\], initial tumor biopsy). OUTLINE: Participants receive ibrutinib orally (PO) once daily (QD) on days 1-28. Courses repeat every 28 days for 5 years in the absence of disease progression or unacceptable toxicity. After completion of study treatment, participants are followed up every 2 months for 6 months, every 2-4 months for 2 years, then every 4-6 months thereafter.