Recently, the trastuzumab biosimilar trastuzumab-dkst (Ogivri®; Viatris Inc, Canonsburg, PA) was approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for the treatment of HER2-overexpressing breast cancer and metastatic gastric or gastroesophageal junction cancer [13, 15]. This evidence concerns the gene ERBB2 and breast carcinoma.