Trastuzumab-Deruxtecan: Redefining HER2 as a Tumor Agnostic Biomarker.

Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate (ADC) targeting HER2-positive malignancies across various tumor types. Through its unique composition, T-DXd achieves selective payload delivery, inducing cell death and halting tumor progression. Clinical trials initially investigated T-DXd's efficacy in HER2-positive advanced or metastatic breast, gastric, lung, and colorectal cancers; however, recent results from the DESTINY-PanTumor02 trial further underscore T-DXd's versatility, prompting T-DXd's US FDA approval for HER2-positive (immunohistochemistry [IHC] 3+) solid tumors. Moreover, in addition to T-DXd's efficacy against brain metastasis, T-DXd is showing promising results in HER2-low and HER2-ultra-low metastatic breast cancer, indicating a broader population of patients who may benefit.