Oncology Nurse AdvisorPermissive Cardiotoxicity Strategy Improves Completion of Trastuzumab Cycles in HER2-Positive Breast Cancer

Permissive cardiotoxicity strategy could enhance trastuzumab treatment outcomes in HER2-positive breast cancer patients, despite requiring more research into its long-term safety.

A study conducted at McMaster University and published in The Oncologist explored the feasibility of a permissive cardiotoxicity strategy in patients with HER2-positive breast cancer undergoing trastuzumab treatment. Although trastuzumab significantly improves outcomes in these patients, up to 4% of them may experience cardiac dose-limiting toxicity (cDLT), resulting in therapy discontinuation, which can negatively impact patient outcomes. The researchers employed a retrospective cohort study of 51 patients who had been referred to the cardio-oncology service between January 2016 and May 2021 for left ventricular dysfunction after trastuzumab administration. Notably, a permissive cardiotoxicity strategy was applied, which allows the continuation of trastuzumab therapy while closely monitoring mild to moderate cardiotoxicity.

The primary outcomes for this study were left ventricular (LV) function and completion of an entire course of trastuzumab. Astonishingly, 92% of patients (47 out of 51) were able to complete their full course of HER2-targeted therapy without experiencing cDLT. However, 6% developed cDLT during trastuzumab treatment, and even after discontinuation, they were more likely to experience persistent cardiotoxicity. Interestingly, despite most patients regaining their LV function post-treatment, 14% persisted with reduced LVEF three years after their initial treatment for LV dysfunction. Despite the promising intermediate-term results, further research on the long-term safety and potential of this strategy is needed.