Real-World Clinical Outcomes in Patients Initiating Covalent Btki (cBTKi) with and without Incident Cardiovascular Adverse Events By Line of Therapy for Chronic Lymphocytic Leukemia (CLL) and Small Lymphocytic Lymphoma (SLL)

Background:

CLL is one of the most common types of leukemia in the United States, with an estimated 20,700 new cases in 2024. Although cBTKis have become the standard of care for CLL/SLL in treatment-naïve and relapsed/refractory patients, cardiovascular (CV) toxicity is a known side effect. Further, clinical outcomes often worsen as patients progress beyond 1^st-line therapy (1L), and the frequency of CV adverse events (CVAEs) may increase with age and as patients progress to 2^nd-line or later therapies (2L+). This research evaluated the real-world incidence of CVAEs and clinical outcomes in patients who initiated cBTKi between 2020 and 2023.

Methods:

Adult patients diagnosed with CLL/SLL who initiated cBTKi treatment (index date) between 2020-2023 in the United States were identified using claims data from Optum’s de-identified Clinformatics® Data Mart Database and followed up to 36 months post-index. Cohorts were assessed as those initiating 1L or 2L+, reflecting treatment-naïve and relapsed/refractory patients. Results were presented for patients with an incident CVAE (not present pre-index) and those without. Demographics, incident CVAEs, overall survival (OS) and proportion of patients who discontinued index cBTKi therapy, initiated next treatment or experienced death (NT+D) were assessed. Time to CV event (TTCE) for ibrutinib and acalabrutinib were determined using a Kaplan-Meier (KM) model and Log rank test.

Results:

Overall, 2,163 eligible patients were identified with a mean ± SD age of 73.8 ± 9.2 years, and 40.6% were female. Of these, 1,958 (90.5%) were included in the 1L cohort and 205 (9.5%) in the 2L+ cohort; 619 (31.6%) and 63 (30.7%) patients had CVAEs, respectively. The mean ± SD [median] observation period was 1.6 ± 0.9 [2.0] years in 1L and 1.5 ± 1.0 [1.0] years in 2L+. The most common cBTKi (in 1L and 2L+) at index were ibrutinib (55.5% and 55.6%), followed by acalabrutinib (40.3% and 38.5%), and zanubrutinib (4.1% and 5.9%).

At 12-months post-index, the proportion of 1L patients with and without CVAEs who discontinued treatment was 44.9% and 41.6%, rising to 65.6% and 59.0% by 36-months post-index, respectively. For those in 2L+, 50.8% and 40.8% of those with and without CVAEs discontinued treatment by 12-months; 68.3% and 55.6% discontinued by 36-months.

Among those with and without CVAEs, NT+D in 1L patients was 35.9% and 22.5% within 12-months post-index and 56.9% and 32.8% by 36-months. In the 2L+ cohort, 46.0% and 31.7% experienced NT+D by 12-months, rising to 63.5% and 41.5% by 36-months.

OS in 1L patients was 84.7% and 93.1% in those with and without CVAEs at 12-months and 69.1% and 88.0% at 36-months. For 2L+ patients, OS was 71.4% and 88.0% at 12-months and decreased to 54.0% and 80.3% at 36-months, among those with and without CVAEs, respectively.

The most common incident CVAEs following cBTKi initiation in the 1L and 2L+ cohorts were hypertension (31.2% and 21.7%), heart failure (14.6% and 17.7%), atrial fibrillation (13.9% and 18.4%), atrial flutter (13.3% and 16.9%), and ventricular arrythmias (13.0% and 14.5%).

The occurrence of incident CVAEs between 1L patients who received acalabrutinib and ibrutinib was 3.4% and 13.2% for atrial fibrillation, 2.7% and 12.7% for atrial flutter, 9.3% and 31.0% for hypertension, and 6.8% and 11.7% for ventricular arrythmias. For 2L+, the proportion experiencing CVAEs with index acalabrutinib or ibrutinib were 8.6% and 14.8% for atrial fibrillation, 7.6% and 14.8% for atrial flutter, 10.5% and 25.0% for hypertension, and 10.1% and 8.8% for ventricular arrythmias. Among acalabrutinib and ibrutinib patients, KM estimates (medians not reached) in 1L showed that 84% and 72% of patients would not experience a CVAE by 12 months, with 57% and 52% not experiencing a CVAE at 36-months (p<0.001); 2L+ KM estimate rates were 77% and 73% at 12-months and 64% and 60% at 36-months (p=0.28). Mean TTCE for acalabrutinib and ibrutinib in 1L was 2.2 and 1.9 years with 1.6 and 1.2 years in 2L+.

Summary/Conclusion:

Utilizing real-world evidence from patients with CLL/SLL receiving cBTKIs, this study highlights the CV disease burden among patients who incur new CV events in 1L or later lines of therapy. This research underscores the need for innovative therapies with improved efficacy and CV safety profiles that delay progression to later lines of therapy, as well as careful CV monitoring to allow for early management and improved outcomes.