This is a multicenter, single-arm, two-part study designed to evaluate the safety and efficacy of Lutetium [177Lu] Oxyoctreotide Injection in patients with inoperable, locally advanced or metastatic, progressive, advanced somatostatin receptor (SSTR) positive neuroendocrine neoplasms (NEN) other than grade G1/G2 gastroenteropancreatic neuroendocrine tumors (GEP-NET).

This study consists of two parts, the exploratory study (Part 1) and the pivotal study (Part 2).

In both parts, participants who signs Informed consent form (ICF) and is eligible for the study will be enrolled. Participants will receive 7.4GBq (200mCi) Lutetium [177Lu] Oxyoctreotide every 8 weeks. The objective tumor response will be assessed every 12 weeks from the time of the first dose according to RECIST 1.1 until disease progression.

Inclusion Criteria:

1. Able to understand and have willingness to provide a written informed consent document.
2. Aged 18 years or older.
3. ECOG performance status 0 or 1.
4. Histopathologically confirmed, unresectable locally advanced or metastatic NEN .
5. Disease progression before first dose.
6. Subjects of childbearing potential should voluntarily use an effective method of contraception during treatment and within 4 months (male) or 7 months (female) of the last dose.

Exclusion Criteria:

1. Known brain metastases, unless these metastases have been treated and stabilized for at least 24 weeks prior to enrollment in the study.
2. Uncontrolled congestive heart failure, including baseline left ventricular ejection fraction (LVEF) <50%.
3. Uncontrolled diabetes mellitus, including baseline fasting glucose > 2 x ULN.
4. Any clinically significant active infection.
5. Pregnant or lactating females.
6. Received systemic antitumor therapy such as targeted therapy, immunotherapy, antitumor herbal therapy or chemotherapy within 4 weeks prior to enrollment.
7. Known other malignancies (except for those without recurrence within 5 years after adequate treatment).
8. Any other disease, mental status or surgical condition that is uncontrolled, may interfere with study completion (including poor compliance) or is inappropriate for the use of the investigational drug.