Sun Yat-Sen University Cancer Center Guang Dong Province, Guangdong
S. Zheng1, S. Ding1, B. Liu1, R. Zhou1, Y. Liu1, M. Chen1, X. Huang1, B. Qiu1, D. Wang1, and H. Liu2; 1State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, China, 2State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
Purpose/Objective(s): This study aimed to assess the therapeutic efficacy of online adaptive MR-guided fractionated stereotactic radiotherapy (FSRT) for brain metastases (BMs) in non-small cell lung cancer (NSCLC) patients using a 1.5T MR-Linac. Materials/
Methods: This phase II, single-arm study enrolled NSCLC patients with 1-10 brain metastases. All eligible patients ranged in age from 18 to 75 years with an Eastern Cooperative Oncology Group performance status of 0-1. Patients were treated with adaptive FSRT at 30Gy in 5 daily fractions guided by online MR imaging on a 1.5T MR-Linac. Bevacizumab was administered before FSRT (day 1) and after FSRT (day 21) at a dosage of 7.5mg/Kg. The primary endpoint was intracranial progression-free survival (IPFS). The secondary endpoints included intracranial overall response rate (ORR), progression-free survival (PFS), overall survival (OS), treatment-related toxicities, and quality of life (QOL) scores. Results: A total of 50 patients were enrolled between July 2021 and June 2023. The median follow-up time was 19.4 months (data cutoff in March 4, 2024). The median age of these patients was 57.5 years (range: 35-77 years), predominantly adenocarcinoma (41/50, 82%). Most patients presented with symptomatic brain metastases prior to treatment (28/50, 56%). Among these patients, 10 experienced intracranial progression, all of which were outside the radiation field. The intracranial ORR was 78%. The median IPFS was 17.7 months (95% confidential interval [CI], 11.9-23.4 months), with a 1-year IPFS rate of 74.4% (95% CI, 62.9%-88.1%). The median PFS was 16.6 months (95% CI, 9.3-24.0 months), with a 1-year PFS rate of 63.7% (95% CI, 51.1%-79.3%). The median OS was 28.4 months (95% CI,17.2-39.7 months), with a 1-year OS rate of 82.4% (95% CI, 72.0%-94.3%). Only one patient (1/50, 2.0%) developed grade (G) 1 radio-necrosis. Significant reductions in tumor volume and peritumoral edema volume were observed after radiotherapy (p<0.05 for both). The overall QOL scores was markedly improved from 81.47 to 95.42 at 6 months following treatment (p<0.01). Conclusion: Online adaptive FSRT conducted on a 1.5T MR-Linac has proven to be an effective treatment for brain metastases from NSCLC. The results of this study are expected to provide important guidance for clinical practice and serve as a reference for further optimizing treatment strategies for patients with brain metastases. (ClinicalTrials.gov identifier: NCT04946019).
