Efficacy and Safety of Sintilimab Combined With Regorafenib and Cetuximab / Sintilimab Combined With Regorafenib in Posterior Line Therapy of Advanced Colorectal Cancer (Regosinti)

Inclusion Criteria:

* 1\. Age ≥18 years old, no gender limitation； 2. Patients with unresectable recurrent or metastatic adenocarcinoma of the colon or rectum, proven histologically or cytologically； 3. Central laboratory tests confirm microsatellite stability (MSS) or microsatellite instability-low (MSI-L) or proficiency of MMR (PMMR)； 4. For patients who have previously failed systemic therapy for relapsed or metastatic colorectal cancer, or who are intolerant to treatment, the time for disease progression after the last systemic therapy should not exceed 3 months。Systemic therapy must contain two or more of fluorouracil, oxaliplatin, and irinotecan, and may include or not targeted therapy (bevacizumab, cetuximab, etc.)； 5. Patients must have a measurable disease (RECIST v1.1)；

  1. Non-lymph node lesions with the longest single diameter ≥10mm, or lymph node lesions with short diameter ≥15mm；
  2. Lesion after previous local treatment, such as radiotherapy or ablation, can also be a measurable target if it has been clearly developed according to RECIST 1.1 and the longest single diameter is ≥10mm。 6．ECOG PS：0-1； 7．Life expectancy of more than 3 months； 8. Good organ function (no blood transfusion, no use of hematopoietic stimulating factor, no albumin or blood products within 14 days prior to examination)；

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  1. platelets(PLT)≥75,000 /mm3；
  2. Absolute neutrophil(ANC)≥1,500 /mm3；
  3. hemoglobin(Hb)≥9.0 g/dl；
  4. international normalized ratio(INR)≤1.5；
  5. Total bilirubin ≤2 times the institutional upper limit of normal (ULN)；
  6. Aspartate aminotransferase(AST)(serum glutamic-oxaloacetic transaminase \[SGOT\])/alanine aminotransferase(ALT)(serum glutamate pyruvate transaminase \[SPGT\])≤3X institutional ULN (or≤5 times ULN in case of liver metastasis)；
  7. Creatinine(Cr)≤1.5×ULN and creatinine clearance(CrCl)≥60mL/min； 9. Use contraception and avoid breast-feeding during the study period and for 3 months after the last dosing;Male subjects must agree to use contraception for the duration of the study and for 3 months after the last dosing； 10. Able to understand and willing to sign written informed consent。

Exclusion Criteria:

* 1\. Study any other malignancy with a primary site or histological type different from that of CRC that was diagnosed within 5 years prior to treatment initiation, other than adequately treated basal or squamous cell skin cancer or cervical carcinoma in situ； 2. Central laboratory tests confirm microsatellite instability-high(MSI-H) or DNA mismatch repair defcient (dMMR)； 3. Previous treatment with Regorafenib, PD-1/PD-L1/PD-L2 antibodies, or other co-stimulatory targets or checkpoints on T cells； 4. Known to be allergic to the study drug or excipient, or to similar drugs； 5. Known allergy to the study drug or excipient, or to similar drugs received immunosuppressive drugs within 2 weeks prior to the commencement of study treatment (excluding inhaled corticosteroids or other systemic steroids ≤10 mg/ day of prednisone or equivalent pharmacological dose)； 6. A live attenuated vaccine was scheduled to be given 4 weeks before the start of study treatment or during the study period； 7. CYP3A4 inducers or inhibitors should not be discontinued 1 week before and during study treatment； 8. Central nervous system metastases are known to occur； 9. Any autoimmune disease or history of autoimmune disease； 10. Presenting any autoimmune disease or unwell controlled hypertension with a history of autoimmune disease (SBP ≥140 mmHg or Diastolic BP ≥90 mmHg)； 11. Clear bleeding tendency, hemoptysis, hematemesis and stool。