Changes in vascular function and correlation with cardiotoxicity in women with newly diagnosed breast cancer undergoing HER2-directed therapy with and without anthracycline/cyclophosphamide.

Aims: The objective of this study was to assess the effect of HER2-directed therapy (HER2-Tx) on peripheral vasoreactivity and its correlation with cardiac function changes and the additive effects of anthracycline/cyclophosphamide (AC) therapy and baseline cardiovascular risk.

Methods And Results: Single-centre, prospective cohort study of women with newly diagnosed stage 1-3 HER2-positive breast cancer undergoing HER2-Tx +/- AC. All participants underwent baseline and 3-monthly evaluations with Endo-Peripheral Arterial Tonometry (Endo-PAT), vascular biomarkers [C-type natriuretic peptide (CNP) and neuregulin-1 beta (NRG-1β)], and echocardiography. Cardiotoxicity was defined as a decrease in the left ventricular ejection fraction (LVEF) of >10% to a value <53%. Of the 47 patients enrolled, 20 (43%) received AC in addition to HER2-Tx. Deterioration of reactive hyperaemia index (RHI) on Endo-PAT by ≥20% was more common in patients receiving HER-Tx plus AC than HER2-Tx alone (65% vs. 22%; = 0.003). A decrease in CNP and log NRG-1β levels by 1 standard deviation did not differ significantly between the AC and non-AC groups (CNP: 20.0% vs. 7.4%; = 0.20 and NRG-1β: 15% vs. 11%; = 0.69) nor did GLS (35% vs. 37%; = 0.89). Patients treated with AC had a significantly lower 3D LVEF than non-AC recipients as early as 3 months after exposure (mean 59.3% (SD 3) vs. 63.8% (SD 4); = 0.02). Reactive hyperaemia index and GLS were the only parameters correlating with LVEF change.

Conclusion: Combination therapy with AC, but not HER2-Tx alone, leads to a decline in peripheral vascular and cardiac function. Larger studies will need to define more precisely the causal correlation between vascular and cardiac function changes in cancer patients.