Phase 1b Study To Investigate The Safety And Tolerability Of Idelalisib In Japanese Patients With Relapsed/Refractory Follicular Lymphoma And Chronic Lymphocytic Leukemia

Objective Idelalisib is an orally administered, highly selective inhibitor of phosphatidylinositol 3-kinase-delta. In this phase 1b study, the safety, tolerability and pharmacokinetics of idelalisib, an oral inhibitor of phosphatidylinositol 3-kinase-delta, were evaluated in Japanese patients with relapsed or refractory indolent B-cell non-Hodgkin lymphoma.Methods In total, six patients (follicular lymphoma: n = 3, chronic lymphocytic leukemia: n = 3) were enrolled to receive idelalisib 150 mg twice daily.Results No dose-limiting toxicities were reported. The most common adverse events were diarrhea (n = 5), gastritis (n = 3), insomnia (n = 3) and pyrexia (n = 3). The most common >= grade 3 adverse events were diarrhea (n = 2), increased transaminase levels (n = 2) and decreased appetite (n = 2). The maximum idelalisib plasma concentrations (Cmax) were achieved at 2.50 h (range: 1.50-4.00 h). The mean idelalisib plasma concentrations decreased over time but remained detectable in most patients at 12 h. All enrolled patients underwent efficacy evaluation by investigators, and five patients (follicular lymphoma: n = 2, chronic lymphocytic leukemia: n = 3) achieved partial response. The median duration of partial response was 14.5 months (range: 3.7-31.3 months).Conclusion Idelalisib 150 mg twice daily was considered tolerable in Japanese patients with follicular lymphoma or chronic lymphocytic leukemia.