[fam‐] trastuzumab deruxtecan, antitumor activity is dependent on HER2 expression level rather than on HER2 amplification

Therapies targeted to human epidermal growth factor receptor 2 (HER2) have proven effective against tumors positive for HER2 amplification, but there is an unmet clinical need for the treatment of tumors that express HER2 protein in the absence of HER2 amplification. [fam-] trastuzumab deruxtecan (DS-8201a) is a novel antibody-drug conjugate composed of the anti-HER2 antibody and the topoisomerase I inhibitor, an exatecan derivative. It has...