Phase II Study to Evaluate the Efficacy and Safety of 177Lu-Dotatate in the First-line Treatment of Patients With Locally Advanced or Metastatic, Somatostatin Receptor-positive G2 or G3 Gastroenteropancreatic Neuroendocrine Tumors

Inclusion Criteria:

1. Ability to understand and willingness to sign a written informed consent document.
2. Aged 18-75 years.
3. Histopathologically confirmed G2 or G3 unresectable locally advanced or metastaticGEP-NET, Ki67 index ≥10 and ≤ 55%. (based on the fifth edition of the WHOclassification and grading criteria for neuroendocrine， tumors of the digestive systemin 2019, to be centrally confirmed).
4. Subjects have not received prior systemic antitumor therapy for the current stage ofNET.
5. Presence of at least 1 measurable site of disease (based on RECIST 1.1).
6. All target lesions (based on RECIST 1.1) at baseline must be confirmed as growthinhibitor receptor positive by 68Ga-Dotatate PET/CT.
7. ECOG score of 0 or 1.
8. Subjects of childbearing potential voluntarily use an effective method ofcontraception, such as condoms, oral or injectable contraceptives, IUDs, etc., duringtreatment and within 3 months of the last use of the trial drug.

Exclusion Criteria:

1. Serum creatinine >150 μmol/L (1.7 mg/dL) or creatinine clearance <50 ml/min (CockcroftGault formula).
2. Hemoglobin <80g/L, or white blood cell count <2.0×109/L, or platelets <75×109/L.
3. Serum total bilirubin > 3 × upper limit of normal (ULN).
4. Serum albumin <30g/L.
5. Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) > 2.5×ULN.
6. International normalized ratio (INR) > 1.5 or partially activated prothrombin time (APTT) > 1.5 x ULN.
7. Pregnant or lactating females.
8. Received peptide receptor radionuclide therapy(PRRT) prior to randomization.
9. Received the following treatments within 4 weeks prior to treatment, including but notlimited to surgery (except biopsy), radical radiotherapy, hepatic arteryinterventional embolization, cryoablation of liver metastases, or radiofrequencyablation.
10. Received systemic antitumor therapy such as targeted therapy, immunotherapy, antitumorherbal therapy, chemotherapy within 4 weeks prior to randomization.
11. Toxicity of prior antitumor therapy has not returned to ≤ grade 1 levels (except foralopecia).
12. Received external beam radiation therapy for bone metastases within 2 weeks prior totreatment.
13. More than 25% of bone marrow with prior external radiation radiotherapy.
14. Known brain metastases, unless these metastases have been treated and stabilized forat least 24 weeks, prior to enrollment in the study.
15. Uncontrolled congestive heart failure.
16. uncontrolled diabetes mellitus, including baseline fasting glucose > 2 x ULN.
17. Any patient receiving treatment with short-acting Octreotide, which cannot beinterrupted for 24 h before and 24 h after the administration of Lutetium[177Lu]Oxodotreotide Injection, or any patient receiving treatment with Octreotide LAR, whichcannot be interrupted for at least 6 weeks before the administration ofLutetium[177Lu] Oxodotreotide Injection.
18. Known other malignancies (except for those without recurrence within 5 years afteradequate treatment)
19. Known hypersensitivity to Lutetium[177Lu] Oxodotreotide Injection or oxytetracyclineacetate microsphere components and their excipients.
20. Known to be unsuitable for enhanced CT or MRI contrast imaging due to allergicreaction or renal insufficiency
21. Any clinically significant active infection, including Positive human immunodeficiencyvirus (HIV) antibody.
22. Positive for hepatitis B virus (HBV) surface antigen (HBsAg) and positive for HBV DNA (≥1×104 copies/ml or judged positive by research center criteria), or positive forhepatitis C virus (HCV) antibodies.
23. Participated in other drug clinical trials within 4 weeks prior to the first treatmentand received treatment with the corresponding trial drug.
24. Any other disease, mental status or surgical condition that is uncontrolled, mayinterfere with study completion (including poor compliance) or is inappropriate forthe use of the investigational drug.
25. Other treatment options (e.g., chemotherapy, targeted therapy) that, in the opinion ofthe investigator, are more appropriate for the patient than the treatment provided inthe study based on the patient's disease characteristics, i.e., the investigationaldrug is not the best therapeutic agent for clinical practice.
26. Subjects who, in the judgment of the investigator, are suspected of having a diseaseor condition that makes them unsuitable for the study drug disease or condition.