The goal of this clinical trial is to learn about efficacy of Rimegepant in combination with PD-1 in patients with liver metastasis colorectal cancer. The main question is to explore the survival time, safety and tolerability of the treatment. At the same time, the correlation between biomarkers (including PD-L1 expression, tumor mutation load, lymphocyte subpopulation, cytokines, TCR, intestinal microbes, and others) and the efficacy and drug resistance mechanism will be analyzed, so as to provide reference for the subsequent guidance of the screening of benefit groups.