Willis, Joseph, Anders, Robert, Torigoe, Toshihiko, Hirohashi, Yoshihiko, Bifulco, Carlo, Zlobec, Inti, Mlecnik, Bernhard, Demaria, Sandra, Choi, Won-Tak, Dundr, Pavel, Tatangelo, Fabiana, Di Mauro, Annabella, Baldin, Pamela, Bindea, Gabriela, Marliot, Florence, Haicheur, Nacilla, Fredriksen, Tessa, Kirilovsky, Amos, Buttard, Bénédicte, Vasaturo, Angela, Lafontaine, Lucie, Maby, Pauline, El Sissy, Carine, Hijazi, Assia, Majdi, Amine, Lagorce, Christine, Berger, Anne, Van den Eynde, Marc, Pagès, Franck, Lugli, Alessandro, and Galon, Jérôme
BACKGROUND: The Immunoscore (IS) is a quantitative digital pathology assay that evaluates the immune response in cancer patients. This study reports on the reproducibility of pathologists visual assessment of CD3+- and CD8+-stained colon tumors, compared to IS quantification. METHODS: An international group of expert pathologists evaluated 540 images from 270 randomly selected colon cancer (CC) cases. Concordance between pathologists T-score, corresponding hematoxylin-eosin (H&E) slides, and the digital IS was evaluated for two- and three-category IS. RESULTS: Non-concordant T-scores were reported in more than 92% of cases. Disagreement between semi-quantitative visual assessment of T-score and the reference IS was observed in 91% and 96% of cases before and after training, respectively. Statistical analyses showed that the concordance index between pathologists and the digital IS was weak in two- and three-category IS, respectively. After training, 42% of cases had a change in T-score, but no improvement was observed with a Kappa of 0.465 and 0.374. For the 20% of patients around the cut points, no concordance was observed between pathologists and digital pathology analysis in both two- and three-category IS, before or after training (all Kappa < 0.12). CONCLUSIONS: The standardized IS assay outperformed expert pathologists T-score evaluation in the clinical setting. This study demonstrates that digital pathology, in particular digital IS, represents a novel generation of immune pathology tools for reproducible and quantitative assessment of tumor-infiltrated immune cell subtypes.