New Standards in Her2-Low Testing: The Casi-01 Comparative Methods Study

• DOI: 10.2139/ssrn.5087372
• Publication Date: 2025-01-09T21:10:19Z
• Authors: David Dabbs; Emina Torlakovic; Soren Nielsen; Suzanne C. Parry; Jing Yu; Catherine Stoos; Beth Clark; Henrik Høeg; Jeppe Thagaard; Seshi Sompuram; Stephen Naber; Yukako Yagi; James Sayre; Kodela Vani; Mélissande Cossutta; Francoise Soussaline; Alexandre Papine; Nils t'Hart; Matthias Szabolcs; Bharat Jasani; Mary Kinloch; Luis Chiriboga; Keith Miller; Steve Bogen

Background: The introduction of Trastuzumab deruxtecan (T-Dxd) has exposed clinically significant limitations in accurately detecting HER2-low expression testing when using immunohistochemistry (IHC) assays originally developed to detect HER2 over-expression. While is widely used determine T-Dxd eligibility, no assay was ever validated as measuring low levels protein expression.