Low-dose Thoracic Radiotherapy Followed by Adebrelimab Plus Chemotherapy, and Then Sequential Maintenance Therapy With Adebrelimab for Extensive-stage Small Cell Lung Cancer

Efficacy and Safety of Low-dose Thoracic Radiotherapy Followed by Adebrelimab Plus Chemotherapy and Sequential Adebrelimab Maintenance Therapy for Extensive-stage Small Cell Lung Cancer: A Prospective, Multicenter Phase II Study

This multicenter, prospective study aims to investigate the efficacy and safety of low-dose radiotherapy (15Gy/1.5 Gy bid × 10 fractions) combined with 4-6 cycles of systemic chemotherapy plus anti-PD-L1 antibody, followed by anti-PD-L1 antibody maintenance for up to two years, in participants with extensive-stage small cell lung cancer (ES-SCLC).

Additionally, dynamic monitoring using next-generation sequencing (NGS) technology will be performed to assess ctDNA levels, genetic information, and mutation abundance at the following time points: before and after low-dose radiotherapy, after 4-6 cycles of chemotherapy plus anti-PD-L1 antibody (chemotherapy-immunotherapy), and before the initiation of anti-PD-L1 maintenance therapy. This approach aims to guide efficacy and prognosis prediction, as well as to identify potential biomarkers associated with treatment response.

Study Overview

• Status: Not yet recruiting
• Conditions: Lung; Radiotherapy
• Intervention / Treatment: Drug: Etoposide; Drug: Cisplatin; Drug: Carboplatin; Drug: Adebrelimab; Radiation: Thoracic Radiotherapy

Detailed Description

This prospective, multicenter study plans to enroll 43 ES-SCLC participants without malignant pleural effusion. All participants will first receive low-dose radiotherapy (15Gy/1.5 Gy bid × 10 fractions), followed by systemic chemotherapy (EP or EC regimen) combined with anti-PD-L1 antibody within one week after radiotherapy completion for 4-6 cycles. After 4-6 cycles of chemo-immunotherapy, anti-PD-L1 antibody maintenance therapy will be continued for two years. This treatment model is expected to achieve survival outcomes (PFS and OS) comparable to or even better than those of the MATCH study from West China Hospital (mPFS 6.9 months) and the NCT04562337 study from Shandong Cancer Hospital (mPFS 6.9-10.1 months), with manageable toxicity.

Furthermore, dynamic monitoring using next-generation sequencing (NGS) technology will be performed to assess ctDNA levels, genetic information, and mutation abundance at three time points: before and after low-dose radiotherapy, and after 4-6 cycles of chemo-immunotherapy (before the initiation of anti-PD-L1 maintenance therapy). This approach is expected to identify potential biomarkers that can guide efficacy and prognosis prediction, thereby better serving clinical practice.

• Study Type: Interventional
• Enrollment (Estimated): 43
• Phase: Phase 2

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Age ≥18 years and ≤75 years.
2. Histologically or cytologically confirmed extensive-stage small cell lung cancer (SCLC).
3. No prior systemic anti-tumor therapy.
4. ECOG performance status 0-2 and life expectancy ≥12 weeks.
5. At least one measurable lesion per RECIST version 1.1.
6. No brainstem metastasis and no significant neurological symptoms from brain metastases.
7. All participants must undergo routine contrast-enhanced CT of the chest and upper abdomen, as well as brain MRI, before enrollment. Whole-body PET-CT plus brain MRI is preferred. For participants with limited financial resources who also have significant obstructive pneumonia or atelectasis, an additional chest MRI is recommended.
8. No malignant pleural effusion or pericardial effusion.
9. All participants must provide written informed consent.

Exclusion Criteria:

1. Presence of interstitial pneumonia or infectious fever prior to treatment.
2. Comorbid autoimmune diseases or long-term oral corticosteroid use (including those who received oral corticosteroids within 14 days prior to treatment).
3. Prior history of thoracic radiotherapy or thoracic surgery.
4. Presence of Grade ≥3 hematologic toxicity or hepatic/renal impairment.
5. Hypersensitivity to adebrelimab.
6. Significant respiratory symptoms that preclude tolerance to radiotherapy.
7. Active hepatitis B or hepatitis C infection with ongoing antiviral therapy. Subjects with a documented history of HBV infection who have achieved undetectable HBV levels after prior active treatment at the time of enrollment may be included.
8. Presence of pleural effusion or pericardial effusion.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Low-Dose Radiotherapy + EP/EC + Adebrelimab; All patients will first receive low-dose radiotherapy. Within one week after completion of radiotherapy, patients will receive concurrent systemic chemotherapy (either EP or EC regimen) combined with adebrelimab for 4-6 cycles. Following the 4-6 cycles of chemo-immunotherapy, patients will continue maintenance therapy with adebrelimab for up to two years.

Drug: Etoposide; Etoposide 100 mg/m² intravenously on days 1-3, plus Cisplatin 75 mg/m² intravenously on day 1, repeated every 21 days (q3w).; Drug: Cisplatin; Etoposide 100 mg/m² intravenously on days 1-3, plus Cisplatin 75 mg/m² intravenously on day 1, repeated every 21 days (q3w).; Drug: Carboplatin; Etoposide 100 mg/m² intravenously on days 1-3, plus Carboplatin area under the curve (AUC) 5 intravenously on day 1, repeated every 21 days (q3w).; Drug: Adebrelimab; 20 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.; Radiation: Thoracic Radiotherapy; Radiotherapy will be delivered to the primary tumor in the lung, involved regional lymph nodes, and metastatic pleural lesions.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Progression-Free Survival（PFS）	Time from first radiotherapy to first occurrence of disease relapse/progression (RECIST 1.1), metastasis, or death from any cause.	From the date of first radiotherapy to the date of first documented disease progression, metastasis, or death from any cause, assessed up to 24 months.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Overall Survival (OS)	Time from first radiotherapy to death from any cause.	From date of first radiotherapy to date of death from any cause, assessed up to 36 months.
Overall Response Rate (ORR)	Proportion of subjects achieving complete response (CR) or partial response (PR) according to RECIST v1.1.	At 3 months after completion of low-dose thoracic radiotherapy.
Disease Control Rate (DCR)	Proportion of subjects achieving CR, PR, or stable disease (SD) according to RECIST v1.1.	At 3 months and 6 months after completion of low-dose thoracic radiotherapy.
Incidence of Treatment-Emergent Adverse Events	Frequency, severity, and relationship of adverse events assessed by CTCAE v5.0.	From date of first low-dose radiotherapy to 30 days after last dose.
Peripheral Blood ctDNA Level	Dynamic changes in circulating tumor DNA (ctDNA) concentration in peripheral blood measured by next-generation sequencing (NGS).	Within 48 hours pre-first low-dose RT (at SCLC diagnosis); within 48 hours post-low-dose RT; within 48 hours pre-anti-PD-L1 maintenance (post 4-6 cycles EP/EC + adebrelimab); and within 48 hours post-confirmed PD.

Collaborators and Investigators

• Sponsor: Jiangmen Central Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): October 30, 2027
• Study Completion (Estimated): January 1, 2028

Study Registration Dates

• First Submitted: April 21, 2026
• First Submitted That Met QC Criteria: May 6, 2026
• First Posted (Actual): May 13, 2026

Study Record Updates

• Last Update Posted (Actual): May 13, 2026
• Last Update Submitted That Met QC Criteria: May 6, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Organic Chemicals; Hydrocarbons; Hydrocarbons, Cyclic; Carbohydrates; Podophyllotoxin; Tetrahydronaphthalenes; Naphthalenes; Polycyclic Aromatic Hydrocarbons; Hydrocarbons, Aromatic; Polycyclic Compounds; Glucosides; Glycosides; Inorganic Chemicals; Chlorine Compounds; Nitrogen Compounds; Coordination Complexes; Platinum Compounds; Etoposide; Carboplatin; Cisplatin
• Other Study ID Numbers: 2026 049 A

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No