Chemoradiation triggers antitumor Th1 and tissue resident memory-polarized immune responses to improve immune checkpoint inhibitors therapy.

BACKGROUND: Multiple synergistic combination approaches with cancer drugs are developed to overcome primary resistance to immunotherapy; however, the mechanistic rationale to combine chemoradiotherapy (CRT) with immune checkpoint inhibitors remains elusive. METHODS: This study described the immunological landscape of tumor microenvironment (TME) exposed to CRT. Tumor samples from patients with rectal cancer (n=43) treated with neoadjuvant CRT or radiotherapy were analyzed by nanostring and immunohistochemistry. Studies in mice were performed using three syngeneic tumors (TC1, CT26 and MC38). Tumor-bearing mice were treated either with platinum-based CRT, radiotherapy or chemotherapy. Anti-CTLA-4 and/or anti-Programmed Cell Death Receptor-1 (PD-1) therapy was used in combination with CRT. The therapy-exposed TME was screened by RNA sequencing and flow cytometry and tumor-infiltrating T lymphocyte functionality was evaluated by interferon (IFN)-γ ELIspot and intracellular cytokine staining. RESULTS: Front-to-front comparison analysis revealed the synergistic effect of CRT to establish a highly inflamed and Th1-polarized immune signature in the TME of patients and mice. In both settings, CRT-exposed TMEs were highly enriched in newly-infiltrated tumor-specific CD8+ T cells as well as tissue resident memory CD103+CD8+ T cells. In mice, CD8 T cells were involved in the antitumor response mediated by CRT and were primed by CRT-activated CD103+ dendritic cells. In the three tumor models, we showed that concurrent combination of CRT with a dual CTLA-4 and PD-1 blockade was required to achieve an optimal antitumor effect and to establish a broad and long-lasting protective antitumor T cell immunity. CONCLUSIONS: Our results highlight the ability of CRT to stimulate strong antitumor T-cell-mediated immunity and tissue resident memory T activation in TME, to foster immune checkpoint inhibitors action. These findings have implications in clinic for the design clinical trials combining chemoradiation with immunotherapy.

Analytical validation of the Immunoscore and its associated prognostic value in patients with colon cancer.

BACKGROUND: New and fully validated tests need to be brought into clinical practice to improve the estimation of recurrence risk in patients with colon cancer. The aim of this study was to assess the analytical performances of the Immunoscore (IS) and show its contribution to prognosis prediction. METHODS: Immunohistochemical staining of CD3+ and CD8+ T cells on adjacent sections of colon cancer tissues were quantified in the core of the tumor and its invasive margin with dedicated IS modules integrated into digital pathology software. Staining intensity across samples collected between 1989 and 2016 (n=595) was measured. The accuracy of the IS workflow was established by comparing optical and automatic counts. Analytical precision of the IS was evaluated within individual tumor block on distant sections and between eligible blocks. The IS interlaboratory reproducibility (n=100) and overall assay precision were assessed (n=3). Contribution of the IS to prediction of recurrence based on clinical and molecular parameters was determined (n=538). RESULTS: Optical and automatic counts for CD3+ or CD8+ were strongly correlated (r=0.94, p<0.001 and r=0.92, p<0.001, respectively). CD3 and CD8 staining intensities were not altered by the age of the tumor block over a period of 30 years. Neither the position of tested tissue sections within a tumor block nor the selection of the tissue blocks affected the IS. Reproducibility of the IS was not affected by multiple variables (eg, antibody lots, DAB revelation kits, immunohistochemistry automates and operators). Interassay repeatability of the IS was 100% and interlaboratory reproducibility between two testing centers was 93%. Finally, in a case series of patients with stage II-III colon cancer, the relative proportion of variance for time to recurrence was greatest for the IS (53% of prognostic variability) in a model that included IS, T-stage, microsatellite instability status and total number of lymph nodes. CONCLUSION: IS is a robust and validated clinical assay leveraging immune scoring to predict recurrence risk of patient with localized colon cancer. The strong and independent prognostic value of IS should pave the way for it use in clinical practice.