This study is a multicenter, prospective investigation aiming to evaluate the efficacy and safety of low-dose radiotherapy (15Gy/1.5 Gy bid × 10 fractions) combined with 4-6 cycles of systemic chemotherapy concurrently with Adebrelimab, followed by Adebrelimab maintenance therapy for up to two years, in subjects with extensive-stage small cell lung cancer (ES-SCLC). Additionally, immunohistochemical detection of the expression levels of four key transcriptional proteins-YAP1, NEUROD1, ASCL1, and POU2F3-will be performed to guide the molecular subtyping of SCLC. Based on these findings, we will explore the differential therapeutic outcomes of this regimen across distinct molecular subtypes (A/N/P/Y/I/AN/QN), with the goal of identifying the subject population most likely to benefit from this treatment modality, thereby optimizing clinical decision-making.
Age ≥18 years and ≤75 years.
Histologically or cytologically confirmed SCLC.
No prior thoracic radiotherapy or thoracic surgery.
No prior systemic anti-tumor therapy.
Pre-existing interstitial lung disease (with or without clinical symptoms) or uncontrolled infectious pneumonia (e.g., accompanied by cough, fever >38°C, dyspnea, tachypnea, etc.) prior to treatment.
Concomitant autoimmune disease, or long-term oral corticosteroid use (including oral corticosteroids within 14 days before treatment).
Allergy to adebrelimab.
Positive HIV antibody, active hepatitis B (HBV-DNA >10³ IU/mL), active hepatitis C (HCV-RNA above the lower limit of detection of the study site), active pulmonary tuberculosis (defined as: fever, night sweats, chest pain, etc.; or acid-fast bacilli found in sputum or bronchoalveolar lavage fluid; or chest CT showing active signs such as patchy infiltrates or cavities), or positive syphilis antibody.
Single group
Etoposide
DrugEtoposide 100 mg/m² on days 1-3 plus cisplatin 25 mg/m² on days 1-3, every 3 weeks (q3w), or etoposide 100 mg/m² on days 1-3 plus carboplatin AUC 5 on day 1, every 3 weeks (q3w).
Cisplatin
DrugEtoposide (100 mg/m²) and cisplatin (25 mg/m²) were administered on days 1-3 of each 3-week cycle.
Carboplatin
DrugEtoposide (100 mg/m²) was given on days 1-3 and carboplatin (AUC 5) on day 1 of each 3-week cycle.
Adebrelimab
Drug20 mg/kg intravenously on day 1, repeated every 21 days (q3w). Administered concurrently with chemotherapy for 4-6 cycles, followed by maintenance monotherapy for up to 2 years.
Thoracic Radiotherapy
RadiationAll subjects will first receive low-dose radiotherapy (DT 15 Gy, 1.5 Gy per fraction × 10 fractions, BID). Within one week after radiotherapy completion, they will receive 4-6 cycles of systemic chemotherapy (EP or EC regimen) combined concurrently with adebrelimab. Following the 4-6 cycles of chemo-immunotherapy, adebrelimab maintenance therapy will be continued for two years.
Progression-Free Survival（PFS）
Progression-free survival (PFS), defined as the time from the initiation of radiotherapy to the first documented disease recurrence/progression, metastasis, or death from any cause.
Overall Survival (OS)
Overall survival (OS), defined as the time from the initiation of radiotherapy to death from any cause.
Overall Response Rate (ORR)
The objective response rate (ORR), defined as the proportion of subjects achieving complete response (CR) or partial response (PR) per RECIST 1.1 criteria based on evaluable lesions in the lungs and distant metastases (including primary tumor, lymph nodes, and distant metastatic lesions), relative to the total enrolled population.
Disease Control Rate (DCR)
The disease control rate (DCR), defined as the proportion of subjects achieving complete response (CR), partial response (PR), or stable disease (SD) per RECIST 1.1 criteria based on evaluable lesions in the lungs and distant metastases (including primary tumor, lymph nodes, and distant metastatic lesions), relative to the total enrolled population.
Incidence of Treatment-Emergent Adverse Events
Frequency, severity, and relationship of adverse events assessed by CTCAE v5.0.
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