Comparable Efficacy of Idelalisib Plus Rituximab and Ibrutinib in Relapsed/refractory Chronic Lymphocytic Leukemia: A Retrospective Case Matched Study of the Polish Adult Leukemia Group (PALG).

Background/aim: There is limited amount of data available on the comparative efficacy of ibrutinib and idelalisib, the B-cell receptor inhibitors (BCRi) newly approved for relapsed/refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (r/r CLL/SLL) treatment. The aim of our study was to analyze and compare the outcomes of real-world r/r CLL/SLL patients treated with these two BCRi in outside clinical trials.

Patients And Methods: A comparative case matched 1:2 analysis was performed on idelalisib combined with rituximab and ibrutinib efficacy in 102 patients with r/r CLL/SLL from two observational studies of the Polish Adult Leukemia Group (PALG).

Results: Both therapies produced similar overall response rates (idelalisib plus rituximab 76.4% and ibrutinib 72.1%). Median progression-free survival (PFS) and overall survival (OS) in both groups were not reached. Furthermore, no significant difference was observed between both BCRi regimens in regard to PFS (HR=0.75, 95% CI=0.30-1.86, p=0.55) and OS (HR=0.65, 95%CI=0.26-1.68, p=0.39).

Conclusion: In summary, the results of this retrospective analysis suggest that idelalisib combined with rituximab and ibrutinib therapies have comparable activity in r/r CLL/SLL in daily clinical practice.