Efficacy of idelalisib in CLL subpopulations harboring del(17p) and other adverse prognostic factors: Results from a phase 3, randomized, double-blind, placebo-controlled trial.

7011^ Background: Idelalisib (IDELA) is a potent and selective inhibitor of PI3Kδ, which is critical for activation, proliferation and survival of B cells and their homing and retention in lymphoid tissues. An unmet need exists for effective therapies in patients with CLL positive for del(17p) and other adverse prognostic factors. This report describes the efficacy of IDELA in combination with rituximab (R) in such high-risk relapsed patients. Methods: Samples for del(17p), del(11q), TP53mut, IGHVmut, ZAP70 and CD38 expression, and β2-microglobulin were collected prospectively and tested using standard methods. Patients were stratified based on presence of del(17p) and/or TP53mut, and on IGHV mutational status. The endpoints evaluated in the high-risk subpopulations in the preplanned 1st interim analysis include progression-free-survival (PFS) and overall response rate (ORR). The primary study analysis was reported in NEJM 2014. Results: IDELA+R retained robust efficacy across all high-risk subpopulations...