1021 - Adebrelimab as Maintenance Therapy Following Hyperfractionated Simultaneous Integrated Boost Radiotherapy Plus Chemotherapy in Limited-Stage Small-Cell Lung Cancer: A Prospective, Multicenter, Single-Arm Phase II Trial
Presenter(s)
J. Yu1, J. Shan1, X. Chang1, D. Yang1, L. Jiang1, L. Long1, Y. Teng1, X. Dong1, R. Yu1, H. Yu1, Q. Li2, S. Ma3, and A. Shi1; 1Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing, China, 2Hospital & Institute Department of Medical Oncology, Ordos Central Hospital, Ordos, China, 3Key Laboratory of Molecular Oncology, Beijing Key Laboratory of Carcinogenesis and Translational Research, Department of Thoracic Surgery I, Peking University Cancer Hospital & Institute, Beijing, China
Purpose/Objective(s): Although twice-daily thoracic radiotherapy with concurrent chemotherapy has been the treatment of choice for limited-stage small-cell lung cancer (LS-SCLC), which has a poor prognosis. the application of hyperfractionated simultaneous integrated boost (HSIB) radiotherapy technology has demonstrated promising local control outcomes. However, the safety and efficacy of maintenance adebrelimab following chemoradiotherapy with accelerated, hyperfractionated, twice-daily thoracic radiotherapy (54 Gy in 30 fractions) remains unexplored.
Materials/Methods: This prospective, multicenter, single-arm Phase II trial enrolled patients with unresectable LS-SCLC who achieved progression-free status after concurrent chemoradiotherapy (cCRT), consisting of etoposide-platinum plus platinum chemotherapy and HSIB radiotherapy (54 Gy/30 fractions). Patients received maintenance adebrelimab 1200 mg every 3 weeks until disease progression, death, intolerable toxicity, or a maximum of 2 years. The primary endpoint was safety, with secondary endpoints included investigator-assessed objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). This study was registered at ClinicalTrials.gov, NCT06784206.
Results: From May to December 2025, 17 patients were enrolled (median age 60.0 years; 88.2% stage III;94.1% previously received prophylactic cranial irradiation). All patients completed at least one cycle of adebrelimab treatment. Treatment-related adverse events (TRAEs) occurred in 41.2% of patients (all Grade 1-2), including pneumonia (29.4%), anorexia (23.5%), and radiation pneumonitis (11.8%). No Grade 3 or higher TRAEs were observed. Among the 16 evaluable patients, the confirmed best responses showed a partial response rate of 6.3% and a stable disease rate of 81.3% (overall disease control rate: 87.5%). Only one progression event occurred during the study period; median progression-free survival and overall survival were not mature at data cutoff.
Conclusion: Maintenance adebrelimab following cCRT with HSIB radiotherapy demonstrated excellent tolerability and promising disease control in LS-SCLC. These results provide the first evidence supporting the safe integration of maintenance immunotherapy with HSIB radiotherapy.