Ibrutinib in Treating Patients With Relapsed Hairy Cell Leukemia (NCT01841723)

Usually NOT eligible if any of the following apply:

• Exclusion Criteria:
• Chemotherapy =\< 21 days prior to first administration of study treatment and/or monoclonal antibody =\< 6 weeks prior to first administration of study treatment
• Patients who are receiving any other investigational agents
• Patients with known brain metastases should be excluded from this clinical trial because of their poor prognosis and because they often develop progressive neurologic dysfunction that would confound the evaluation of neurologic and other adverse events
• History of allergic reactions attributed to compounds of similar chemical or biologic composition as ibrutinib
• Ibrutinib is extensively metabolized by CYP3A4/5; patients who received a strong cytochrome P450 (CYP) 3A inhibitor within 7 days prior to the first dose of ibrutinib or patients who require continuous treatment with a strong CYP3A inhibitor; therefore, any medications or substances that are strong inhibitors of CYP3A4/5 should be discontinued; patients unable to change these medications must be excluded from participation; because the lists of these agents are constantly changing, it is important to regularly consult a frequently-updated list; medical reference texts such as the Physicians' Desk Reference may also provide this information; as part of the enrollment/informed consent procedures, the patient will be counseled on the risk of interactions with other agents, and what to do if new medications need to be prescribed or if the patient is considering a new over-the-counter medicine or herbal product
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements; recent infections requiring systemic treatment need to have completed therapy \> 14 days before the first dose of study drug
• Pregnant women are excluded from this study because ibrutinib is a tyrosine kinase inhibitor with the potential for teratogenic or abortifacient effects; because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with ibrutinib, breastfeeding should be discontinued if the mother is treated with ibrutinib
• Human immunodeficiency virus (HIV)-positive patients will be eligible unless they have been previously diagnosed with an acquired immune deficiency syndrome (AIDS)-defining illness
• Patients who require anticoagulation with warfarin (Coumadin) or who have taken warfarin within 28 days prior to enrollment are not eligible due to a potential increased risk of hemorrhage; patients who are currently taking vitamin K antagonists are also ineligible for this study
• Patients requiring daily corticosteroids at a prednisone equivalent of \>= 20 mg daily should not be enrolled; if corticosteroids can be discontinued (or reduced to \< 20 mg per day of prednisone or equivalent), the discontinuation or dose reduction should be done at least 7 days prior to first dose
• Prior exposure to a Bruton's tyrosine kinase (BTK) inhibitor