Clinical Study of Surufatinib Plus Sintilimab Combined With Chemotherapy in the Treatment of Advanced Gastric Neuroendocrine Carcinoma

Inclusion Criteria: To be enrolled in this trial, patients must meet all of the following inclusion criteria:

1. Locally advanced or metastatic gastric neuroendocrine carcinoma (NEC),hyperproliferative neuroendocrine tumor (NET G3) or mixedneuroendocrino-non-neuroendocrine tumor (MiNEN), as demonstrated by pathology (WHOclassification criteria 2019), may also be included;
2. Have not received systematic anti-tumor therapy before;
3. Have received radical treatment in the past and have no treatment interval from theend of chemotherapy, radiotherapy, or chemoradiotherapy to relapse for at least 6months (the end time of the last chemotherapy cycle/the end time of the lastradiotherapy);
4. There are measurable lesions defined by the RECIST 1.1 standard;
5. At least 18 years old;
6. ECOG physical condition: 0-1 score;
7. Expected survival of more than 3 months;
8. If the major organs function normally, the following criteria are met:
9. Blood routine examination: hemoglobin (Hb) ≥90g/L; Absolute neutrophil count (ANC) ≥1.5×10^9/L; Platelet (PLT) ≥100×10^9/L; White blood cell count (WBC) ≥3.0×10^9/L;
10. Biochemical examination: alanine aminotransferase (ALT) and aspartateaminotransferase (AST) ≤2.5×ULN (tumor liver metastasis, ≤5×ULN); Serum totalbilirubin (TBIL) ≤1.5×ULN (Gilbert syndrome subjects, ≤3×ULN); Serum creatinine (Cr) ≤1.5×ULN or creatinine clearance ≥50ml/min;
11. Coagulation function: activated partial thromboplastin time (APTT), InternationalStandardized ratio (INR), prothrombin time (PT) ≤1.5×ULN;
12. The subjects voluntarily joined the study, signed the informed consent, and thecompliance was good.

Exclusion Criteria: Patients with any of the following conditions were excluded from the study:

1. The presence of a serious illness or medical condition, including but not limited tothe following:
2. Known recurrence in situ or metastasis at any other site;
3. systemic active infection (i.e. infection resulting in body temperature ≥38 ° C);
4. Clinically significant intestinal obstruction, pulmonary fibrosis, renal failure,liver failure, or symptomatic cerebrovascular disease;
5. Severe/unstable angina, New York Heart Association (NYHA) Class III or IVsymptomatic congestive heart failure;
6. Clinically significant gastrointestinal bleeding;
7. Known presence of human immunodeficiency virus (HIV) or acquired conventionalimmunodeficiency syndrome (AIDS) - associated disease, or active hepatitis B orC;
8. Pregnant or lactating women;
9. The researcher considers it inappropriate to enter this study.