Ibrutinib related bleeding complications in elderly patients with B cell malignancies

Cardiovascular Risk Associated With Ibrutinib Use in Chronic Lymphocytic Leukemia: A Population-Based Cohort Study

PURPOSE

Ibrutinib reduces mortality in chronic lymphocytic leukemia (CLL). It increases the risk of atrial fibrillation (AF) and bleeding and there are concerns about heart failure (HF) and central nervous system ischemic events. The magnitude of these risks remains poorly quantified.

METHODS

Using linked administrative databases, we conducted a population-based cohort study of Ontario patients who were treated for CLL diagnosed between 2007 and 2019. We matched ibrutinib-treated patients with controls treated with chemotherapy but unexposed to ibrutinib on prior AF, age ≥ 66 years, anticoagulant exposure, and propensity for receiving ibrutinib. Study outcomes were AF-related health care contact, hospital-diagnosed bleeding, new diagnoses of HF, and hospitalizations for stroke and acute myocardial infarction (AMI). The cumulative incidence function was used to estimate absolute risks. We used cause-specific regression to study the association of ibrutinib with bleeding rates, while adjusting for anticoagulation as a time-varying covariate.

RESULTS

We matched 778 pairs of ibrutinib-treated and unexposed patients with CLL (N = 1,556). The 3-year incidence of AF-related health care contact was 22.7% (95% CI, 19.0 to 26.6) in ibrutinib-treated patients and 11.7% (95% CI, 9.0 to 14.8) in controls. The 3-year risk of hospital-diagnosed bleeding was 8.8% (95% CI, 6.5 to 11.7) in ibrutinib-treated patients and 3.1% (95% CI, 1.9 to 4.6) in controls. Ibrutinib-treated patients were more likely to start anticoagulation after the index date. After adjusting for anticoagulation as a time-varying covariate, ibrutinib remained positively associated with bleeding (HR, 2.58; 95% CI, 1.76 to 3.78). The 3-year risk of HF was 7.7% (95% CI, 5.4 to 10.6%) in ibrutinib-treated patients and 3.6% (95% CI, 2.2 to 5.4) in controls. There was no significant difference in the risk of ischemic stroke or AMI.

CONCLUSION

Ibrutinib is associated with higher risk of AF, bleeding, and HF, but not AMI or stroke.

Emerging small-molecule inhibitors of the Bruton's tyrosine kinase (BTK): Current development

Therapy based on Bruton's tyrosine kinase (BTK) inhibitors one of the major treatment options currently recommended for lymphoma patients. The first generation of BTK inhibitor, Ibrutinib, achieved remarkable progress in the treatment of B-cell malignancies, but still has problems with drug-resistance or off-target induced serious side effects. Therefore, numerous new BTK inhibitors were developed to address this unmet medical need. In parallel, the effect of BTK inhibitors against immune-related diseases has been evaluated in clinical trials. This review summarizes recent progress in the research and development of BTK inhibitors, with a focus on structural characteristics and structure-activity relationships. The structure-refinement process of representative pharmacophores as well as their effects on binding affinity, biological activity and pharmacokinetics profiles were analyzed. The advantages and disadvantages of reversible/irreversible BTK inhibitors and their potential implications were discussed to provide a reference for the rational design and development of novel potent BTK inhibitors.

Outcomes of Reduced Frequency Dosing of Ibrutinib in Chronic Lymphocytic Leukemia Patients Following Complete or Partial Remission: A Pilot Study

Background

Ibrutinib is a Bruton’s tyrosine kinase inhibitor that has shown to be a superior choice in the treatment of chronic lymphocytic leukemia (CLL) and a simple, oral alternative to other chemoimmunotherapies. The standard dose is 420 mg daily; however, its irreversible binding mechanism allows adequate target blockade at much lower doses due to prolonged effect. Dose reductions or interruptions are often used in clinical practice to limit its distinct side effects, including diarrhea, bleeding and atrial fibrillation and emerging evidence exists that these do not hinder efficacy. Using a retrospective clinical audit of a single-center outpatient hematology clinic, we aimed to examine outcomes and toxicities of a reduced frequency dose regimen of ibrutinib in patients beyond the confines of a clinical trial.

Methods

A small pilot study was conducted on 16 voluntary CLL patients that had achieved partial or complete remission on standard dose ibrutinib and were considering cessation due to side effects. Patients were consented and prescribed a 420 mg thrice weekly regimen and side effects and outcomes were recorded on routine review. A retrospective clinical audit from 2015 to 2018 was then conducted to compare pilot participants to patients that had remained on standard dosing and results from the extended follow-up of the landmark RESONATE trial.

Results

None of the 16 patients in the pilot relapsed or died during the study period equating to a 100% progression free and overall survival. There was resolution or reduction in all side effects reported following switchover; however, the study was too small to establish a statistical relationship.

Conclusion

This is the first study to demonstrate use of a thrice weekly regimen to reduce ibrutinib-related toxicities whilst preserving safety and efficacy in patients following complete or partial remission on standard dose therapy. Higher powered, prospective studies are required to establish positive health and financial implications in the elderly and vulnerable CLL demographic.