Long-term Efficacy of Ibrutinib in Relapsed or Refractory Chronic Lymphocytic Leukemia: Results of the Polish Adult Leukemia Study Group Observational Study.

Background/Aim: To study the long-term clinical efficacy and tolerability of ibrutinib monotherapy in real-world relapsed and refractory chronic lymphocytic leukemia (RR-CLL) patients outside clinical trials. Patients and Methods: Clinical data of 171 RR-CLL patients treated with ibrutinib were collected within the observational study of the Polish Adult Leukemia Study Group. Results: Median patient age was 64 years. Patients were pretreated with 3 (1-10) median lines of therapy, while 42 (24.6%) had 17p deletion. The median observation time was 40 months (range=1-59 months), while median ibrutinib monotherapy reached 37.5 months (range=0.4-59.2 months). Response was noted in 132 (77.2%) patients. The estimated 5-year progression-free survival (PFS) and overall survival (OS) rates were 61.1% (95%CI=49.3-70.9%) and 56.8% (95%CI=45.6-66.6%), respectively. At the time of analysis 97 (56.7%) remained under ibrutinib monotherapy. Conclusion: Ibrutinib is clinically effective and tolerable as a monotherapy in real-world RR-CLL patients.