Objective: Idelalisib is an orally administered, highly selective inhibitor of phosphatidylinositol 3-kinase-δ. In this phase 1b study, the safety, tolerability and pharmacokinetics of idelalisib, an oral inhibitor of phosphatidylinositol 3-kinase-δ, 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.(Clinical trial registration: NCT02242045).
Keywords: chronic lymphocytic leukemia; follicular lymphoma; idelalisib; phase 1 study; safety.
© The Author(s) 2020. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.