Heed Cardiac Risk of Bruton Tyrosine Kinase Inhibitors for CLL

Randy Dotinga

July 22, 2022

A new, industry-funded consensus statement from an international team of hematologists, oncologists, and cardio-oncologists urges caution regarding the cardiac risks of Bruton tyrosine kinase inhibitors (BTKis) in treating chronic lymphocytic leukemia (CLL).

The report discourages the use of the drugs in patients with heart failure, and it specifies that ibrutinib should be avoided in cases of ventricular fibrillation. The consensus statement appeared in the journal Blood Advances.

However, a physician who studies the intersection of cardiology and oncology questioned the report's methodology and said that it goes too far in its warnings about the use of BTKis. Also, the report is funded by AstraZeneca, which produces acalabrutinib, a rival BTKi product to ibrutinib.

"BTK inhibitors have revolutionized treatment outcomes and strategies in both the upfront and refractory CLL disease settings. Led by ibrutinib, the drugs are associated with dramatic improvements in long-term survival and disease outcomes for most CLL patients," report co-author and cardiologist Daniel Addison, MD, co-director of the cardio-oncology program at the Ohio State University, said in an interview. "The main cardiac concerns are abnormal heart rhythms, high blood pressure, and heart weakness. It is not completely clear at this time why these things develop when patients are treated with these important drugs."

For the new consensus statement, colleagues met virtually and examined peer-reviewed research. "Generally, this statement reflects available knowledge from cancer clinical trials," Addison said. "Because of the design of these trials, cardiac analyses were secondary analyses. In terms of clinic use, this should be balanced against a large number of heart-focused retrospective examinations specifically describing the cardiac effects of these drugs. Most of the available heart-focused studies have not been prospective trials. Primary outcome heart-focused trials with BTK inhibitors are needed. This statement acknowledges this."

The report recommends that all patients under consideration for BTKi therapy undergo electrocardiograms and blood pressure measurement, and it states that echocardiograms are appropriate for patients with heart disease or at high risk. Patients under 70 without risk factors may take ibrutinib, acalabrutinib, or zanubrutinib, while the latter two drugs are "generally preferred" in patients with established heart disease, well-controlled atrial fibrillation (AFib), hypertension, heart failure, or valvular heart disease.

The authors noted: "If the patient has difficult-to-manage AF[ib], recent acute coronary syndromes, or difficult to control heart failure, alternatives to BTKi treatment, including venetoclax, should be considered."

As for patients with heart failure, the authors wrote that BTKis should be avoided, "but this is a relative contraindication, not an absolute one." Ibrutinib should definitely be avoided because of the risk of AFib.

Finally, the authors stated that "the use of BTKis, especially ibrutinib, should be avoided in patients with a history of ventricular arrhythmias and cardiac arrest. Ibrutinib has been shown to increase the incidence of ventricular arrhythmias and sudden cardiac death. Although data are not yet available regarding whether second-generation BTKis [acalabrutinib or zanubrutinib] are also associated with these events, a Bcl-2 antagonist is preferred to any BTKi in these patients."

Darryl P. Leong, MBBS, PhD, MPH, director of the cardio-oncology program at McMaster University, Hamilton, Ont., and Hamilton Health Sciences, said in an interview that the consensus statement has important limitations.

"The data extracted were not standardized. The authors of the original research were not contacted to provide data that might have been informative," he said. "Finally and perhaps most importantly, I am uncertain that the quality of the data on which recommendations are made was well evaluated or described."

Specifically, Leong said the report’s conclusions about heart failure and arrhythmias are not "necessarily well-supported by the evidence."

He added: "While there is some evidence to suggest that BTKIs may increase heart failure risk, ibrutinib leads to substantial reductions in mortality. It is a large extrapolation to accept that a mostly theoretic risk of heart failure –with modest supporting empiric data – should outweigh proven reductions in death."

As for the recommendation against the use of ibrutinib in patients with ventricular arrhythmias and cardiac arrest, he said the evidence cited by the report – an analysis of adverse event data prompted by a case report and a retrospective analysis – is limited. "The statement that ibrutinib increases the risk of ventricular arrhythmias and sudden death is more of a hypothesis at present, and the evidence to support this hypothesis is far from conclusive."

As for the future, report co-author Addison said that "additional prospective and lab-based studies of these drugs are needed to guide how to best manage their cardiac effects in the future. This will be critical, as the use of these drugs continues to rapidly expand. Currently, we do not know a lot about why these heart issues really happen."

The study was funded by AstraZeneca. Several authors reported multiple disclosures. Addison disclosed funding from AstraZeneca. Leong reported consulting and speaker fees from Janssen, maker of ibrutinib, as well as AstraZeneca.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.


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