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Validation of the Immunoscore (IM) as a prognostic marker in stage I/II/III colon cancer: Results of a worldwide consortium-based analysis of 1,336 patients.
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2016
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ImmunologyGastroenterologyPathologyImmunotherapyPrognostic MarkerOncologyGastrointestinal OncologyTumor ImmunityMolecular OncologyCancer ResearchColorectal CancerSitu Immune InfiltrateImmune SurveillanceTumor MicroenvironmentPrognostic BiomarkersCancer ImmunosurveillanceIm MethodologyWorldwide Consortium-based AnalysisGastrointestinal PathologyPrimary CcsMedicine
3500 Background: Mounting evidence indicates an enhanced lymphocytic reaction as an informative prognostic indicator in colon cancer (CC). The IM methodology has been defined to quantify the in situ immune infiltrate. Methods: A Society for Immunotherapy of Cancer-led international consortium of 23 pathology expert centers from 17 countries was initiated to evaluate the standardized IM assay in routine clinical settings. Patient (pt) eligibility criteria were CC Stages I/II/III and no neo-adjuvant treatment. 1336 pts split into a training set (TS) and internal validation set (IVS) were quantified for IM using standardized procedure, immunohistochemistry using CD3 and CD8 antibodies, and quantification using digital pathology on whole slide section of primary CCs. Statistical analysis plan was pre-defined and all statistical analyses performed by blinded external statisticians. Primary study endpoint was time-to-recurrence (TTR); analyses were by Cox models stratified by enrolling center. Results: Median recurrent follow-up duration across centers was 5.9 years. Overall pts: 51% Male, median age 69 years, 19%/56%/25% stage I/II/III. Among pts with Stages I/II/III CC, in the TS TTR was shorter among 332 pts (48.1%) with Low-IM CC vs. 358 pts with High-IM CC (HR (95% CI), 0.35 (0.23-0.52); P < 0.0001). In the IVS (630 pts) TTR was also shorter among 303 pts with Low-IM CC vs. 327 pts with High-IM CC (HR (95% CI), 0.54 (0.34-0.84); P = 0.006). In both groups, results were independent of pt age, sex, tumor stage and sidedness. Among pts with Stage II CC, the difference in TTR between Low and High-IM was significant both in the TS (HR (95% CI), 0.27 (0.14-0.51); P < 0.0001) and in the IVS (HR (95% CI), 0.46 (0.24-0.87) P = 0.014); multivariate results similar (TS HR (95% CI), 0.28 (0.14-0.54); P < 0.0001) and IVS HR (95% CI), 0.46 (0.24-0.87); P = 0.0142)). Reproducibility of the standardized IM assay was validated across centers. Conclusions: The primary endpoint of the worldwide pre-specified IM study was reached. TTR was significantly longer in pts stages I/II/III with High-IM. Low-IM identified a subgroup of patients with high-risk stage II CC.