Study of Tislelizumab Combined With DisitamabVedotin and Pyrotinib Maleate in HER2-positive or Mutated Advanced Colorectal Cancer Who Failed Standard Therapy

"Tislelizumab: 200 mg, d1, intravenous infusion (ivgtt) administration, 21 days as a cycle.~DisitamabVedotin : 2mg/kg, d1, intravenous drip (ivgtt) administration, 21 days as a cycle.~Pyrotinib maleate tablets: 320 mg each time, Qd, orally administered within 30 minutes after breakfast, 21 days as a cycle.~Continuous administration until disease progression, death, toxicity intolerance, withdrawal of informed consent, or other reasons specified in the protocol; for patients who still benefit after comprehensive evaluation after initial disease progression, the investigator may decide whether to continue the treatment with the experimental drug ."