Idelalisib (PI3K inhibitor) therapy for patients with relapsed/refractory chronic lymphocytic leukemia: A Swedish nation-wide real-world report on consecutively identified patients

Objectives: We examined the efficacy and toxicity of the PI3K delta inhibitor idelalisib in combination with rituximab salvage therapy in consecutively identified Swedish patients with chronic lymphocytic leukemia (CLL). Methods and Results: Thirty-seven patients with relapsed/refractory disease were included. The median number of prior lines of therapy was 3 (range 1-11); the median age was 69 years (range 50-89); 22% had Cumulative Illness Rating Scale (CIRS) >6 and 51% had del(17p)/TP53 mutation. The overall response rate was 65% (all but one was partial response [PR]). The median duration of therapy was 9.8 months (range 0.9-44.8). The median progression-free survival was 16.4 months (95% CI: 10.4-26.3) and median overall survival had not been reached (75% remained alive at 24 months of follow-up). The most common reason for cessation of therapy was colitis (n = 8, of which seven patients experienced grade =3 colitis). The most common serious adverse event was grade =3 infection, which occurred in 24 patients (65%). Conclusions: Our real-world results suggest that idelalisib is an effective and relatively safe treatment for patients with advanced-stage CLL when no other therapies exist. Alternative dosing regimens and new PI3K inhibitors should be explored, particularly in patients who are double-refractory to inhibitors of BTK and Bcl-2.