Idelalisib for relapsed/refractory indolent B-cell non-Hodgkin's lymphoma: an overview of pharmacokinetics and clinical trial outcomes.

Indolent non-Hodgkin's lymphoma (iNHL) describes a group of B-cell lymphomas with a long median survival and a relapsing-remitting clinical course. Although existing treatments are initially effective, patients often relapse, demonstrating decreasing efficacy with successive treatment courses. Alternative treatments are needed. PI3Kδ plays an essential, non-redundant role in B-cell receptor signaling critical to the pathogenesis of iNHL. It is expressed predominantly in hematopoietic cells, making PI3Kδ an attractive therapeutic target. Idelalisib is an oral PI3Kδ inhibitor approved in 2014 in the USA and the EU as monotherapy in relapsed follicular lymphoma or relapsed small lymphocytic lymphoma previously treated with two or more prior systemic therapies, or as part of combination therapy with rituximab in patients with chronic lymphocytic leukemia, for whom rituximab monotherapy would be considered appropriate due to the presence of comorbidities. Herein, we review the available data for idelalisib, with an emphasis on relapsed/refractory B-cell iNHL.