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Cardiac toxicity low among patients treated with adjuvant trastuzumab
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Incidence of cardiac toxicity appeared low among patients with early HER-2–positive breast cancer who received adjuvant treatment with trastuzumab, according to results of the randomized phase 3 PHARE trial.
Most cardiac events appeared reversible after discontinuation of trastuzumab (Herceptin, Genentech), researchers wrote.
Trastuzumab improves outcomes for women with early HER-2–positive breast cancer, but prior studies have shown cardiotoxicity rates between 2% and 7%.
The French National Cancer Institute sponsored the PHARE trial, which included 3,380 patients with early HER-2–positive breast cancer randomly assigned 1:1 to the standard 12-month trastuzumab regimen or a 6-month regimen.
In 2013, after 3.5 years median follow-up, researchers were unable to improve the shorter course was noninferior to the standard 12-month course with regard to DFS.
“[However], questions remain regarding whether the magnitude of benefit derived from 1 year of treatment is sufficient to justify its systematic use since the risk of cardiac damage is not negligible,” Xavier Pivot, MD, professor at Jean Minjoz University Hospital in Besancon, France, and colleagues wrote.
In the current analysis, researchers performed cardiac follow-up and left ventricular ejection fraction (LVEF) assessment by echocardiography or multigated acquisition scan every 3 months during trastuzumab treatment and during the first 2 years after treatment, followed by every 6 months thereafter.
Cardiac heart failure served as the primary cardiac endpoint. Secondary cardiac endpoints included cardiac events, cardiac dysfunctions, LVEF decreases and cardiac recoveries.
Results showed incidence of cardiac heart failure was 0.65% among patients assigned the standard 12-month regimen and 0.53% among patients assigned the 6-month regimen, a difference that was not statistically significant. Cardiac dysfunction occurred in 5.9% of patients assigned the 12-month regimen and 3.4% of patients assigned the 6-month regimen (P = .001).
Most patients who experienced cardiotoxicities recovered over time. Among the 20 patients with cardiac heart failure, one patient assigned to the 12-month regimen and three patients assigned to the 6-month regimen failed to recover within 2 years of the event. Median time to recovery was 4.3 months (interquartile range [IQR], 3.1-14.3).
The majority (92.4%) of patients with cardiac dysfunction recovered, with median time to recovery of 6.1 months (IQR, 4-10.5).
Twenty-seven patients (0.79%) experienced an unfavorable cardiac outcome, according to researchers.
“PHARE confirms that the incidence of cardiac endpoints remains low but not null, and that these endpoints are mostly reversible after trastuzumab discontinuation,” Pivot and colleagues wrote. “Identification at baseline of cardiac risk categories of patients should be of interest to provide an optimal adaptation of adjuvant modalities of treatment aimed to avoid deleterious therapy interruption and cardiac dysfunctions.” – by Anthony SanFilippo
Disclosure: The researchers report research funding or honoraria from AstraZeneca, Eisai, GlaxoSmithKline, Johnson & Johnson, Roche and Teva.
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