Safety survey on infusion reaction and cardiac dysfunction when switching from reference trastuzumab (HERCEPTIN®) to biosimilar trastuzumab (Trastuzumab‑NK) in the treatment of HER2‑positive breast cancer.

The present study is a safety survey of patients with human epidermal growth factor receptor type 2-positive, chemotherapy-naive breast cancer treated with trastuzumab plus paclitaxel at the Saitama Cancer Center (Saitama, Japan) between April 2018 and March 2022. The expression of infusion reaction (IR) and the effect on cardiac function were investigated in patients who switched from reference trastuzumab (HERCEPTIN^®) to biosimilar trastuzumab (Trastuzumab-NK) and continued treatment (switching group). The two groups (reference vs. biosimilar trastuzumab) had no significant difference in the expression of IR (P>0.999). In the switching group, IR associated with switching did not occur in all nine eligible patients. Left ventricular ejection fraction (LVEF) was used to assess cardiac function, and no patient in either group experienced a significant decrease in LVEF with treatment, meaning that there was no effect of switching on the decrease in LVEF. These results suggested that switching from reference to biosimilar trastuzumab may not have a significant effect on the frequency of IR expression or the occurrence of cardiac dysfunction.