Presenters: Lynnette Henshaw, PharmD, BCOP, Boston Medical Center, Boston, MA; Camille Edwards, MBBS, Boston Medical Center, Boston University Chobanian & Avedisian School of Medicine, Boston, MA
BACKGROUND: The use of Bruton tyrosine kinase (BTK) inhibitors has increased over the past several years, changing the treatment landscape of hematologic malignancies, such as chronic lymphocytic leukemia (CLL). Ibrutinib was the first BTK to be FDA-approved in 2013, followed by the next-generation BTK inhibitors acalabrutinib and zanubrutinib, which were approved in 2017 and 2019, respectively. Each BTK inhibitor has its unique side-effect profile as well as its class effects. Real-world, long-term data in diverse patient populations are pertinent for the continued evaluation of safety outcomes and disease management.
OBJECTIVE: To describe the real-world use of BTK inhibitors, including treatment-related adverse effects, in a diverse patient cohort.
METHOD: This is a retrospective study of patients with hematologic malignancies who received BTK inhibitors between January 2016 and December 2021 at Boston Medical Center (BMC), a large safety net hospital. Using the oncology pharmacy database, we captured all of the prescriptions that were sent during the study period. Patients were excluded if their primary treatment was at another institution or if they did not start their intended therapy. Baseline demographics, therapy information, and safety data were collected after the patients had completed at least 6 months of therapy.
RESULTS: A total of 36 patients received treatment at BMC from January 2016 to December 2021 with either ibrutinib (n = 31), acalabrutinib (n = 4), or zanubrutinib (n = 1) in the first-line or relapsed/refractory setting. The median age of the patients was 70 years, and the majority of patients were male (61.1%), black or African American (42%), and diagnosed with CLL (52.8%). Approximately 50% of the patients receiving ibrutinib or acalabrutinib and the 1 patient who received zanubrutinib had a treatment interruption. A total of 19 patients (61.3%) who were receiving ibrutinib discontinued therapy, with 45.2% (n = 14) resulting from treatment-related adverse drug reactions (ADRs). Half of the patients receiving acalabrutinib (n = 2) discontinued therapy, with 25% of the discontinuations resulting from ADRs. Of the patients receiving ibrutinib, a worsening of existing atrial fibrillation (Afib) or new Afib was seen in 6.5% (n = 2) and 9.8% (n = 3), respectively. The patient receiving zanubrutinib had new Afib. None of the patients who were receiving acalabrutinib had Afib. New hypertension was diagnosed in 16.1% (n= 5) of the patients receiving ibrutinib and 25% (n = 1) of the patients receiving acalabrutinib. Worsening of existing hypertension was reported in 6.5% (n = 2) of the patients receiving ibrutinib.
CONCLUSION: BTK inhibitors are associated with cardiac adverse events, such as hypertension and Afib, which can develop many months to years after therapy initiation. Knowledge of therapy-related toxicities in diverse populations is essential for appropriate monitoring for the development of adverse events.
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