A Clinical Study of Exploring Camrelizumab in the Treatment of Colorectal Mucinous Adenocarcinoma(MAC)

Inclusion Criteria: * 1\. Join the study voluntarily and sign the informed consent; * 2\. Unresectable locally advanced or metastatic colorectal mucinous adenocarcinoma or colorectal adenocarcinoma containing mucinous gland components diagnosed by histopathology or cytology; * 3\. Patients who have received at least first-line and above systemic chemotherapy (which may include platinum, fluorouracil, or irinotecan-based) progress or intolerance (maintenance treatment progress after first-line chemotherapy can also be included). Simultaneous chemoradiotherapy for recurrence or metastasis after surgery is considered as first-line treatment; for radical concurrent chemoradiotherapy, neoadjuvant/adjuvant therapy (chemotherapy or radiochemotherapy), if disease progression occurs during treatment or within 6 months after stopping treatment, It should be counted as a failure of first-line treatment; * 4\. Age 18-75 years old (including boundary value, calculated on the day of signing informed consent), both men and women; * 5\. ECOG score 0-2 points; * 6\. Blood routine and liver and kidney function meet the following conditions: neutrophil count\>1.5\*10\^9/L, hemoglobin concentration\>90g/L, platelet count\>80\*109/L; ALT and AST\<2.0\*ULN (with liver The transferee may be \<5.0\*ULN); * 7\. Estimated survival time\> 3 months; * 8\. Willing to accept long-term follow-up, willing to provide tumor tissue samples, willing to provide blood samples before and after treatment; Exclusi…