Real-world experience of ibrutinib therapy in relapsed chronic lymphocytic leukemia: results of a single-center retrospective analysis

BACKGROUND: Ibrutinib is a Bruton’s tyrosine-kinase (BTK) inhibitor that is approved as a second-line treatment in chronic lymphocytic leukemia (CLL). While recent trials have demonstrated impressive results for ibrutinib, there remains a paucity of real-world data on its use in the clinical setting. METHODS: In this single-center study carried out at Brighton and Sussex University Hospitals, we retrospectively compared outcomes in 38 patients with relapsed CLL who received ibrutinib versus those who received conventional first- and second-line therapies. RESULTS: Our results demonstrate improved progression-free survival (PFS, p=0.022) with ibrutinib versus conventional second-line therapies and survival comparable to conventional first-line therapies. However, there was a high frequency (81.6%) of adverse events associated with ibrutinib therapy, including 2 cases of death secondary to sepsis and a further 7 cases of discontinuation of treatment due to adverse events. We also identify del13q14.3 as an adverse predictor of response to ibrutinib with respect to both overall survival (p=0.014) and PFS (p=0.008), suggesting that these patients may be better suited to receiving the BCL2 inhibitor venetoclax. CONCLUSION: Whilst there is robust evidence for improved outcomes with ibrutinib, we find that survival in patients with del13q14.3 is reduced and that the rate of adverse events and discontinuation in clinical practice is higher than anticipated from clinical trials.