It has the potential to be a sizeable new indication for Enhertu (trastuzumab deruxtecan), a HER2-targeting antibody-drug conjugate, and central to AZ and Daiichi Sankyo’s hopes of unlocking multibillion-dollar sales for the drug.
According to the FDA, out of the almost 290,000 new cases of breast cancer diagnosed in women in 2022, between 80% to 85% would be considered HER2-negative under the old grouping system.
Around 60% of that HER2-negative group can now be considered as HER2-low – roughly 140,000 cases using a back-of-the-envelope calculation – who can now consider Enhertu treatment as an alternative to endocrine therapy or chemotherapy.
