e15508 Background: Immune related biomarkers (IRB) are important predictors of outcome to immune checkpoint inhibitor (ICI) therapy; however, their role is unclear in early-stage colorectal cancer (CRC). This study aimed to evaluate the expression of novel protein IRB among CRC patients to predict clinical outcomes. Methods: A CRC tumor microarray (TMA) was constructed from a multiracial patient population, and expression of HHLA2, B7-H3, PD-L1, CK7, CK20, and CDX2 determined. Comprehensive clinical information was extracted. For curable cancers, associations between biomarker expression and relapse risk were assessed using logistic regression analysis. For metastatic(m) cancers, Kaplan Meier curves were plotted, and Cox proportional hazards regression analysis was performed to evaluate association with overall survival (OS). Results: Among 388 patients, 150 had de novo metastatic disease, 108 experienced relapses from localized cancer, and 130 patients had cured localized disease. The median age was 62.4 years, with a female predominance (53%). The majority were racial/ethnic minorities. Among curable cancers, patients with high B7-H3 expression experienced a 73% lower risk of relapse (OR 0.27, 95%Cl 0.09-0.76, p = 0.015) exceeding the relevance of nodal(N) and tumor(T) stage in predicting relapse. High HHLA2 (OR 4.79, 95%CI 1.74-14.5, p = 0.003) was associated with a higher risk of relapse. Among mCRC, low expression of both PD-L1 and B7-H3 was associated with better OS (HR 1.73; 95%CI 1.08-2.76, p = 0.023). Conclusions: In this multiracial TMA of CRC, high B7-H3 expression was associated with lower risk of relapse. Post validation, routine B7-H3 testing may enable clinicians to make more informed decisions regarding adjuvant therapy.