Ibrutinib discontinuation in patients with relapsed or refractory chronic lymphocytic leukemia treated in a compassionate use program: A report from the Polish Adult Leukemia Study Group (PALG).

Background: Development of a novel class of drugs, the B-cell receptor-signaling inhibitors, including ibrutinib, has been a major achievement in the therapy of refractory or relapsed chronic lymphocytic leukemia (CLL). However, the CLL patients who have discontinued the ibrutinib treatment in clinical trials have been reported to have poor prognosis.

Objectives: In this retrospective study by the Polish Adult Leukemia Group (PALG), we analyzed the reasons for ibrutinib cessation and outcomes after discontinuing ibrutinib in refractory or relapsed CLL patients treated in a compassionate use program in Poland.

Material And Methods: Polish CLL patients were included if they discontinued ibrutinib for any reason. The clinical data on the course of ibrutinib treatment was collected anonymously using electronic Case Report Forms (CRFs). The causes of discontinuation of ibrutinib as reported by the treating physicians were analyzed.

Results: Thirty-seven patients who discontinued ibrutinib were identified. The median duration of ibrutinib treatment in this group was 4.4 months (range: 0.2-25.2). The main reason for discontinuing ibrutinib was adverse events (n = 20, 54%), while 14 (38%) patients discontinued therapy due to disease progression and 3 (8%) due to other causes. The most common treatment complications that led to ibrutinib cessation were severe respiratory tract infections (9 patients, 24%). In the group discontinuing ibrutinib for progressive disease, 11 patients progressed with untransformed CLL, while in 3 patients, a rare type of Richter transformation to Hodgkin's lymphoma was diagnosed. Twenty-nine patients (78%) died during the follow-up period, and median overall survival (OS) reached 2.0 months (95% CI = 0.8-5.5 months). Importantly, no significant survival difference was detected between patients who discontinued ibrutinib due to disease progression and due to adverse events.

Conclusions: The results of this analysis indicate that ibrutinib discontinuation in relapsed or refractory CLL is associated with poor prognosis regardless of the reason for ibrutinib cessation.