After treatment discontinuation, the antitumorigenic effects of regorafenib + anti-PD-1 antibody therapy were rapidly abrogated; however, the combination regimen of regorafenib +anti-PD-1 antibody + chidamide not only significantly prolonged the survival time and led to sustained suppression of relapse, but also resulted in induction of immunity for the tumor growth inhibition of secondary CT26 cell inoculation in a rechallenge test (Table 1 and Table 2). Here, PDCD1 is linked to neoplasm.