TROP2 Expression in Colorectal Tumors

FFPE colorectal tumor samples were obtained from excision biopsies as described previously^{14 (link)}. Tissue blocks were assembled. Slices (2 µM thick) were stained with HE, TROP2 (1:2000, rabbit IgG, ab214488, Abcam, Cambridge, UK), and H3K4me3 (1:1000, rabbit IgG, #9751, Cell Signaling, Danvers, USA). The samples were scored for TROP2 expression by a pathologist (KEW). The total immunostaining score (0–300) consists of the intensity (0–3) and the percentage of positive cells (0–100%). Using the median of 90, the tumor samples were categorized into a TROP2 high-expressing group (> 90) and a TROP2 low-expressing group (< 90).