Phase II Study of Ibrutinib in Patients With Relapsed or Refractory Marginal Zone Lymphoma

Patient sample: Patients with histologically proven marginal zone lymphoma (splenic, nodal and extra-nodal subtypes included). Other important requirements for recruitment into the study: * Prior treatment with one or more lines rituximab or rituximab-based chemoimmunotherapy with failure to achieve at least a partial response (PR) or documented disease progression * Age ≥ 21 years of age * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 * At least 1 measurable disease site on computed tomography (CT) scan that is at least 1.5cm in the longest dimension. * Patient must have an indication for treatment e.g., symptoms from disease, bulky disease (\>5cm), threatened end-organ function, or cytopenias requiring transfusion or growth factor support Dosage and Dose Regimen: 560mg of Ibrutinib is administered orally once daily. Patients with mild liver impairment (Child's-Pugh A), ibrutinib 140mg (1 x 140mg capsule) will be administered instead. The patient will continue on treatment until one of the following occurs: * Patient has disease progression (as assessed by the investigator). * Patient has an intercurrent illness or adverse events that prevents further ibrutinib administration. * Patient decides to withdraw from the study. * Investigator considers withdrawal to be in the best interest of the patient. * Patient requires continuous therapy on a prohibited concomitant medication and no alternative medications or therapies are available as a replacement to the prohibited medication. * Patient is lost to follow-up. * Patient is non-compliant. * Patient becomes pregnant. * Study termination by the Sponsor or regulatory authority. * Death * Completed 3 years of ibrutinib treatment Assessment: CT Neck to pelvis or FDG-PET/CT skull base to mid-thigh to be performed repeated after every 12 weeks Statistical considerations: The primary objective of this study is to determine the efficacy of ibrutinib in Asian patients with relapsed or refractory MZL. We will consider an ORR of 50% to be desirable. Simon's 2-stage minimax design will be used to test the null hypothesis that the overall response rate will be less than or equal to 20% (response rate that is considered not clinically compelling). Twelve subjects will be included in the first stage, and if there are at least 3 responders, a total of 21 subjects will be enrolled. The treatment will be declared ineffective if there are less than 8 responders in total. This design has 90% power to detect an overall response rate of 50% at a 5% significance level. Study Endpoints: Primary: 1\. Overall response rates (complete remission \[CR\] + partial remission \[PR\]) Secondary: 1. Survival parameters * Progression-free survival * Overall survival 2. Safety * Frequency and severity of adverse events * Frequency of AE requiring discontinuation of study drug or dose reductions Total sample size: The planned sample size is 21 patients enrolled at multiple centres in Singapore and South Korea