Efficacy and Safety Study of Fostamatinib Tablets to Treat B-cell Lymphoma

This multicenter, open-label study of fostamatinib will take place in two phases. Phase I Two cohorts, of 6 patients each, will be sequentially assigned to receive 200 mg (Cohort 1) and 250 mg (Cohort 2) PO bid of R788. Patients will be enrolled at 250 mg bid in Cohort 2 only if \< 1/6 patients in Cohort 1 experience dose-limiting toxicity (DLT) during the initial 28-day treatment period. If 2 or more patients in Cohort 1 experience DLT during the initial 28-day treatment period, patients in Cohort 2 will receive 150 mg PO bid. Patients who do not experience DLT or disease progression may continue treatment at the assigned dose level until disease progression, toxicity or withdrawal. Patients who experience DLT may resume treatment at a lower dose level (dose will be decreased by 50 mg) when the toxicity grade has decreased to ≤ 1. Once all patients in Phase I have completed 28 days of treatment, the optimal dose of fostamatinib, based on safety and anti-tumor activity, will be determined. Phase II 48 additional patients, 3 groups of 16 patients each, will receive fostamatinib at the optimal biologic dose PO bid until tumor progression, limiting toxicity or withdrawal. Group 1 will consist of patients with diffuse large B-cell lymphoma (DLBCL), Group 2 will consist of patients with follicular lymphoma, and Group 3 will consist of patients with mantle cell lymphoma, mucosa-associated lymphoid tissue (MALT) lymphoma, marginal zone lymphomas, small lymphocytic lymphomas (SLL), and chronic lymphocytic leukemia (CLL).