The Link between the Multiverse of Immune Microenvironments in Metastases and the Survival of Colorectal Cancer Patients

Treatment of metastatic colorectal cancer is based upon the assumption that metastases are homogeneous within a patient. We quantified immune cell types of 603 whole-slide metastases and primary colorectal tumors from 222 patients. Primary lesions, and synchronous and metachronous metastases, had a heterogeneous immune infiltrate and mutational diversity. Small metastases had frequently a low Immunoscore and T and B cell score, while a high Immunoscore was associated with a lower number of metastases. Anti-epidermal growth factor receptor treatment modified immune gene expression and significantly increased T cell densities in the metastasis core. The predictive accuracy of the Immunoscore from a single biopsy was superior to the one of programmed cell death ligand 1 (PD-L1). The immune phenotype of the least-infiltrated metastasis had a stronger association with patient outcome than other metastases. [Display omitted] •Inter- and intra-metastatic immune infiltrates are heterogeneous in colorectal cancer•T cell densities from metastases increase following anti-EGFR treatment•Immunoscore (IS) outperforms PDL1 staining in metastatic biopsy diagnostic accuracy•IS and TB score from the least-infiltrated metastasis are most survival associated Van den Eynde et al. quantify immune cell types in metastases and primary colorectal tumors. They show that high Immunoscore (IS) associates with fewer metastases, that anti-EGFR treatment significantly increases T cell density in the core of metastases, and that the predictive accuracy of IS better than PDL1.