In this single-center,open-label, phase I study, the safety and efficacy of PIN in combination with anti-programmed cell death -1 (anti-PD1) antibody therapeutic regimen (sintilimab) will be evaluated in patients with advanced proficient mismatch repair/microsatellite stable (pMMR/MSS) colorectal cancer (CRC) with hepatic metastases . A total of 25 to 30 patients are planned to be enrolled and receive PIN plus sintilimab combined treatment. It aims to:
1).assess the safety and antitumor effects of the above combined treatment regimen. 2).detect the dynamic changes and molecular characteristics of PIN induced CD8+ T cells with special phenotype in peripheral blood (PB) and transformation of tumor microenvironment (TME) after the treatment with PIN. 3).evaluate the immunological or clinical predictive biomarkers for toxicity and efficacy.