Regorafenib Plus PD-1 Inhibitor in Patients With Colorectal Cancer

Inclusion Criteria: * Advanced Colorectal Cancer diagnosed histologically; * Patients with microsatellite stable (MSS) * Patients have no any standard choice after multiple line of therapy( ≥ 2 lines); * Expected survival ≥ 3 month; * ECOG / PS score: 0-2, and the main organ function to meet the following criteria: HB ≥ 90g / L, ANC ≥ 1.5 × 109 / L, PLT ≥ 80 × 109 / L,BIL \<1.5 times the upper limit of normal (ULN); Liver ALT and AST \<2.5 × ULN and if liver metastases, ALT and AST \<5 × ULN; Serum Cr ≤ 1 × ULN, endogenous creatinine clearance ≥50ml/min Exclusion Criteria: * Patient still has standard treatment therapy based on NCCN guidance; * Patient can not comply with research program requirements or follow-up;