Golidocitinib With PD-1 Inhibitors as Maintenance Treatment for Previously Untreated ES-SCLC

Inclusion Criteria: 1. Able to provide a signed and dated informed consent form, including compliance with the requirements and restrictions listed in the ICF and this protocol; 2. Subjects are ≥ 18 years old when signing the ICF; 3. Subjects have an ECOG performance status score of 0 or 1 and have not deteriorated in the past 2 weeks; 4. Life expectancy ≥ 3 months; 5. Histologically or cytologically confirmed ES-SCLC (stage IV \[any T stage, any N stage, M1 a/b/c stage\] according to the 8th edition of the AJCC TNM staging system for lung cancer, or T3-4 stage disease caused by multiple lung nodules and the disease is too diffuse, or the tumor/nodule volume is too large to be tolerated by a tolerable radiotherapy plan); 6. The presence of at least one measurable lesion (based on RECIST 1.1): with a long diameter ≥ 10 mm (lymph node lesions require a short diameter of ≥15 mm) that can be accurately and repeatedly measured at baseline under CT or MRI; and there are measurable lesions outside the central nervous system; 7. SCLC patients who have not received any systemic anti-tumor treatment for advanced disease; if the patient has received neoadjuvant/adjuvant therapy in the past, the interval between the diagnosis of ES-SCLC and the completion of the last treatment must be at least 6 months; 8. Patients must be suitable for platinum (cisplatin or carboplatin)-based chemotherapy as the first-line treatment for ES-SCLC; 9. Adequate bone marrow reserve and organ system function reserve, summarized as follows: * Absolute neutrophil count (ANC) ≥ 1.5×109/L without growth factor support; * Platelet ≥ 100×109/L without growth factor support or blood transfusion; * Hemoglobin ≥ 9 g/dL or 90 g/L without erythropoietin or blood transfusion; * Total bilirubin ≤ 1.5 × ULN; if suffering from Gilbert syndrome (unconjugated hyperbilirubinemia), total bilirubin should be ≤ 3 × ULN; * ALT and AST ≤ 2.5 × ULN. For patients with documented liver metastases, AST and ALT levels ≤ 5 × ULN; * Creatinine clearance calculated by the Cockcroft-Gault method, \>60 ml/min for patients receiving cisplatin and \>45 ml/min for patients receiving carboplatin; * Urine routine examination shows less than 2+ protein in urine, or 24-hour urine protein quantitative \<1 g; * Good coagulation function, defined as international normalized ratio (INR) and/or prothrombin time (PT) ≤1.5 times ULN and/or activated partial thromboplastin time (APTT) ≤1.5 upper limit of normal; if the subject is receiving anticoagulant therapy, as long as the PT is within the intended use range of the anticoagulant drug; * Serum amylase ≤1.5 times ULN and/or serum lipase ≤1.5 times ULN; * Left ventricular ejection fraction (LVEF) ≥ 55%; 10. For patients with central nervous system metastases, the following conditions must be met before they can be included: * No neurological symptoms or symptoms are stable for at least 2 weeks after local treatment, no need to use corticosteroids or anti-epileptic drugs, and hormonal treatment has been stopped within 3 days before the first dose of study drug; * If brain metastases have been treated locally (radiotherapy or surgery), there should be a time window of ≥ 2 weeks before the first dose of study treatment to ensure that local treatment-related adverse events have been reduced to CTCAE ≤ 1 grade; 11. Women of childbearing potential must undergo a urine and/or serum pregnancy test (if the urine test cannot be confirmed as negative) within 7 days before the first medication, and the result must be negative; WOCBP or men and their WOCBP partners should agree to take effective contraceptive measures from the signing of the ICF until 6 months after the last dose of the study drug; 12. The subjects should be able to understand the study protocol and voluntarily comply with the study and follow-up; 13. For patients who are about to enter the maintenance period, the investigator shall determine whether they are suitable for starting treatment with golidocitinib combined with PD-1 inhibitors (generally all previous toxicities must be alleviated to CTCAE ≤ 1 level, excluding hair loss, fatigue or other conditions that are judged by the investigator to be clinically insignificant). Exclusion Criteria: 1. Histopathological confirmation of the presence of mixed NSCLC and SCLC components; 2. The presence of spinal cord compression or meningeal metastasis; 3. Any of the following medical histories: * Systemic treatment with Chinese patent medicines with anti-lung cancer indications or immunomodulatory drugs (including thymosin, interferon, interleukin, excluding local use for the control of pleural effusion) within 2 weeks before the first dose; * Currently participating in interventional clinical research treatment, or receiving other research drugs or using research devices within 4 weeks before the first dose; any drug still in the development stage needs to be washed out for 5 half-lives (or discussed with the research team); * Other major surgeries other than diagnosis or biopsy (excluding vascular access) within 4 weeks before the first dose, or major surgery is expected during the study; * Palliative radiotherapy within 2 weeks before the first dose; * Serious arterial/venous thrombotic events, including cerebrovascular accident (e.g., history of stroke or intracranial hemorrhage), deep vein thrombosis, and pulmonary embolism, occurred within 6 months before the first dose; * Currently receiving (or unable to stop taking at least 1 week before the first dose) drugs, herbal supplements, and foods that are known to be strong inducers or inhibitors of CYP3A; * Prior to the first dose, there was a CTCAE caused by previous treatment \> Grade 1 adverse events (except alopecia of any degree); 4. Receiving solid organ or blood system transplantation (such as previous allogeneic bone marrow transplantation or whole blood transfusion within 120 days of sample c