DKK1 and neoplasm: Previous studies demonstrated that the mechanisms of immune resistance to ICIs might involve mutations in the Wnt/β-catenin pathway [10], PI3K-AKT-mTOR pathway [11,12], CDH1 gene [13], elevated expression of Dickkopf 1 (DKK1) [14], and heterogeneity in tumor mutation burden and tumor microenvironment [15].