Toripalimab Plus Cetuximab and Irinotecan for second-line right-sided colon cancer

Inclusion Criteria:

Participants must meet all of the following criteria to be eligible for this study:

1. Aged 18 years or older, regardless of sex.
2. Patients with previously treated recurrent or metastatic right-sided colon cancer.
3. Confirmed RAS and BRAF wild-type status based on molecular testing.
4. Disease progression following first-line systemic anticancer therapy that did not include anti-EGFR monoclonal antibodies or irinotecan.
5. Eastern Cooperative Oncology Group (ECOG) performance status of 0-1, a life expectancy of at least 3 months, and the ability to cooperate with efficacy and safety assessments.
6. At least one measurable tumor lesion according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.
7. Adequate organ function, defined by the following laboratory criteria:

   * Absolute neutrophil count ≥1.5 × 10⁹/L; platelet count ≥100 × 10⁹/L; hemoglobin ≥9 g/dL; serum albumin ≥3 g/dL.
   * Thyroid-stimulating hormone (TSH) ≤1 × upper limit of normal (ULN), with T3 and T4 levels within normal ranges.
   * Total bilirubin ≤1.5 × ULN; alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤2 × ULN.
   * Serum creatinine ≤1.5 × ULN and creatinine clearance ≥60 mL/min.
   * International normalized ratio (INR) or prothrombin time (PT) ≤1.5 × ULN, unless the participant is receiving anticoagulant therapy and PT is within the intended therapeutic range.
   * Activated partial thromboplastin time (aPTT) ≤1.5 × ULN.
8. No severe concomitant disease associated with a life expectancy of less than 5 years.
9. Female participants of childbearing potential must have a negative pregnancy test. Female participants without childbearing potential are also eligible.
10. Male participants of reproductive potential and female participants of childbearing potential must agree to use adequate contraception throughout the study and for 12 months after completion of study treatment.
11. Provision of signed and dated written informed consent after receiving information about all relevant aspects of the study.
12. Willingness and ability to comply with scheduled visits, treatment plans, laboratory tests, and other study procedures.
13. Agreement not to participate in any other clinical trials involving drugs or medical devices during the study period.

Exclusion Criteria:

Participants meeting any of the following criteria will be excluded:

1. Pathologically confirmed intestinal tumors other than colon cancer, such as gastrointestinal stromal tumors.
2. Previous treatment with anti-PD-1, anti-PD-L1, or anti-CTLA-4 antibodies.
3. History of or concurrent malignancies other than colon cancer, except adequately treated non-melanoma skin cancer, cervical carcinoma in situ, or papillary thyroid carcinoma.
4. Active autoimmune disease or a history of autoimmune disorders, including but not limited to interstitial pneumonitis, colitis, hepatitis, hypophysitis, vasculitis, nephritis, hyperthyroidism, or hypothyroidism. Exceptions include autoimmune hypothyroidism controlled with a stable dose of thyroid hormone replacement therapy, type 1 diabetes mellitus controlled with a stable insulin regimen, vitiligo, or resolved childhood asthma/allergies requiring no intervention in adulthood.
5. History of immunodeficiency, including positive human immunodeficiency virus (HIV) testing, acquired or congenital immunodeficiency disorders, organ transplantation, or allogeneic bone marrow transplantation.
6. History of interstitial lung disease (excluding radiation pneumonitis not requiring corticosteroid treatment) or noninfectious pneumonitis.
7. Active tuberculosis infection identified through medical history or computed tomography (CT), a history of active tuberculosis within 1 year before enrollment, or a history of active tuberculosis more than 1 year before enrollment without adequate treatment.
8. Active hepatitis B infection, defined as HBV DNA ≥2,000 IU/mL or ≥10⁴ copies/mL, or active hepatitis C infection, defined as positive hepatitis C antibody with HCV RNA above the lower limit of detection.
9. Severe cardiac, pulmonary, or renal dysfunction.
10. Uncontrolled hypertension despite antihypertensive treatment, defined as systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg.
11. History of psychotropic drug abuse, excessive alcohol consumption, or illicit drug use.
12. Any other condition that, in the investigator's judgment, may compromise participant safety or compliance with study procedures, including severe concomitant diseases requiring treatment (including psychiatric disorders), clinically significant laboratory abnormalities, or relevant family or social factors.