“The combination of dual HER2 blockade is so far as safe as anti-HER2 monotherapy in terms of cardiotoxicity,” Dr. Antonis Valachis told Reuters Health by email. “As a result, the clinicians who choose such combinations for the treatment of their patients or propose a clinical study to their patients with combination should not be worried about increased cardiac toxicity.”
As reported May 29 online in the International Journal of Cancer, Dr. Valachis of the University of Uppsala, Sweden, and colleagues conducted a meta-analysis of six randomized trials. Overall, 1,142 patients received combined anti-HER2 therapy and 1,473 received anti-HER2 monotherapy.
In fact, the incidence of congestive heart failure (CHF) was 0.88% in the combination group and 1.49% in monotherapy patients (odds ratio 0.58).
Corresponding rates of left ventricular ejection fraction (LVEF) decline to less than 50% or 10% below baseline were 3.1% and 2.9% (odds ratio 0.88).
Subgroup analyses showed no association between combination therapy and CHF or LVEF, neither in the two trials in the metastatic setting nor in the four trials in the adjuvant setting.
In fact, say the investigators, “we could not find a subgroup in which dual anti-HER2 blockade was associated with excess cardiac toxicity.”
Still, they caution, “Appropriate patient selection and cardiac monitoring are essential to prevent and manage potential cardiac adverse events.”
As they stand, pending further study, the results “are valid for patients with adequate cardiac function at baseline (namely before the start of combination therapy),” Dr. Valachis said.