Figure 4. Whole section analysis of immunostaining of CDH17 and CLDN18.

A. The proportion of staining was classified into four stepwise categories according to IHC scores: Category 1 (strongly positive (+++)) corresponding to a score of 8–10 by dark red and dark blue; Category 2 (moderately positive (++)), score of 5–7 by light orange and light blue; Category 3 (weakly positive (+)), IHC score_1–4 by pale orange and pale blue; and Category 4 (negative; absent staining (−)), IHC score_0 by both black. B. Schematic depiction of immunostaining quantification for CDH17 and CLDN18. Two cases each are shown for CDH17 and CLDN18. Circular defect parts of each section are where TMA cores were obtained. Left upper panel shows Group 1_01, with an IHC score (Pr) for CDH17 of 20. Whole sections in the primary lesion and nodal metastasis show diffuse and strong immunostaining of CDH17 in Category 1. The left lower panel shows Group 2_10, with an IHC score (Pr) for CDH17 of 20. Whole sections of primary lesions show heterogeneous immunostaining of CDH17 in Categories 1 to 4. The right upper panel shows Group 3_36, with an IHC score (Pr) in CLDN18 of 18. Whole sections in primary lesion and nodal metastasis show diffuse and strong immunostaining of CLDN18 in Category 1. The right lower panel shows Group 3_26, with an IHC score (Pr) in CLDN18 of 20. Whole sections of primary lesions show heterogeneous immunostaining in Categories 1 to 4. C. Representative cases with high IHC scores (Pr) in CDH17 and CLDN18 were evaluated in whole tissue sections. Sample names are expressed as Group-x_case number (IHC score in TMA). CDH17 showed homogeneous and strong immunostaining in most cases. Some cases showed Category 4 (negative) in CDH17; however, all nodal metastases show strong positive staining (Category 1 or 2). Although CLDN18 also showed clear immunostaining, the pattern was slightly more heterogeneous than that of CDH17 and some nodal metastases in Category 4 (negative or absent staining).