Inclusion Criteria:
1. Colorectal cancer patients aged ≥ 18 years and ≤ 75 years;
2. ECOG score 0-1;
3. Patients with advanced colorectal cancer who are pathologically diagnosed as HER2 expression or mutation and who fail or are intolerant after second-line treatment; Note: HER2 expression refers to patients with tumor cell immunohistochemical staining intensity of 1+, 2+or 3+confirmed to have expression at least once in the pathological detection/review of primary or metastatic lesions conducted by the pathology department of our hospital, or patients with advanced colorectal cancer with HER2 gene amplification or mutation confirmed by NGS.
4. According to RECIST 1.1 standard, there is at least one measurable target lesion, and tumor imaging evaluation is conducted within 28 days before the first drug use;
5. Estimated survival time ≥ 12 weeks;
6. If the main organs function normally, they meet the following standards:
(1) The blood routine examination standard should meet: ANC ≥ 1.5 × 109/L； PLT ≥90 × 109/L； Hb ≥ 90g/L (no blood transfusion within 14 days); (2) Biochemical examination shall meet the following standards: ALB ≥ 30g/L; (No ALB within 14 days); TBIL ≤ upper limit of normal value (ULN); ALT and AST ≤ 2.5 times the upper limit of normal value (ULN). If there is liver metastasis, ALT and AST ≤ 5ULN; Alkaline phosphatase ≤ 2.5 times the upper limit of normal value (ULN); BUN and Cr ≤ 1.5 × ULN and creatinine clearance ≥ 50 mL/min (Cockcroft Gault formula); (3) Color Doppler echocardiography and echocardiography: left ventricular ejection fraction (LVEF ≥ 50%); (4) QT interval (QTcF) corrected by Fridericia method of 12 lead ECG in women\<470 ms; 7. For female patients without menopause or surgical sterilization: during the treatment period and at least 7 months after the last administration of the drug in the study treatment, agree to abstinence or use effective contraception methods; 8. Volunteer to join the study and sign the informed consent form.
Exclusion Criteria:
1. Have received anti-tumor treatment or radiotherapy for any malignant tumor in the past;
2. At the same time, they received anti-tumor therapy in other clinical trials, including endocrine therapy, bisphosphate therapy or immunotherapy;
3. The patient has undergone major surgery unrelated to colorectal cancer within 4 weeks before enrollment, or the patient has not fully recovered from such surgery;
4. Serious heart disease or discomfort, including but not limited to the following diseases:
* History of diagnosis of heart failure or systolic dysfunction (LVEF\<50%)
* High risk uncontrolled arrhythmia, such as atrial tachycardia, resting heart rate\>100 bpm, significant ventricular arrhythmia (such as ventricular tachycardia) or higher grade atrioventricular block (i.e. Mobitz II second degree atrioventricular block or third degree atrioventricular block)
* Angina requiring anti angina drugs
* Valvular heart disease with clinical significance
* ECG showed transmural myocardial infarction
* Poor control of hypertension (systolic blood pressure\>180 mmHg and/or diastolic blood pressure\>100 mmHg)
5. Inability to swallow, intestinal obstruction or other factors affecting drug administration and absorption;
6. People known to have a history of allergy to the drug components of this protocol; Have a history of immunodeficiency, including HIV test positive, HBV/HCV test positive, or have other acquired or congenital immunodeficiency diseases, or have a history of organ transplantation;
7. Women in pregnancy and lactation, women with fertility and positive baseline pregnancy test, or women in childbearing age who are unwilling to take effective contraceptive measures during the whole trial period and within 7 months after the last study drug use;
8. Suffer from serious concomitant diseases or other concomitant diseases that may interfere with the planned treatment, or The investigator believes that the patient is not suitable to participate in any other situation of this study.
