Ibrutinib for relapsed/refractory chronic lymphocytic leukemia: a UK and Ireland analysis of outcomes in 315 patients

Abstract

In 2014, ibrutinib was made available for relapsed/refractory chronic lymphocytic leukemia patients. The UK Chronic Lymphocytic Leukaemia Forum collected data from UK/Ireland patients with a minimum of 1 year follow-up with pre-planned primary endpoints; the number of patients still on therapy at 1 year “discontinuation-free survival” and 1 year overall survival. With a median of 16 months follow up, data on 315 patients demonstrated a 1 year discontinuation-free survival of 73.7% and a 1 year overall survival of 83.8%. Patients with better pre-treatment performance status (0/1 vs. 2+) had superior discontinuation-free survival (77.5% vs. 61.3%; P14 days and had an overall survival rate of 89.7%, while 26% of patients had dose reductions and 13% had temporary treatment breaks of >14 days. We could not demonstrate a detrimental effect of dose reductions alone (1 year overall survival: 91.7%), but patients who had first year treatment breaks of >14 days, particularly permanent cessation of ibrutinib had both reduced 1 year overall survival (68.5%), and also a statistically significant excess mortality rate beyond one year. Although outcomes appear inferior to the RESONATE trial (1 year overall survival; 90%: progression-free survival; 84%), this may partly reflect the inclusion of performance status 2+ patients, and that 17.5% of patients permanently discontinued ibrutinib due to an event other than disease progression.