189 - Hypofractionated Radiotherapy plus Concurrent Chemotherapy with or without Consolidation Immunotherapy in Patients with Locally Advanced Non-Small Cell Lung Cancer (GASTO-1052)

P. Zhang¹, D. Wang², F. Liu³, R. Zhou², S. Zheng², Q. Luo³, B. Hou¹, J. Guo³, Y. Situ⁴, Y. Dong¹, B. Qiu², and H. Liu³; ¹Sun Yat-sen University Cancer Center, Guangzhou, China, ²State 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, ³State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China, ⁴Sun Yat-sen University Cancer Center, GuangZhou, China

Purpose/Objective(s): We aimed to determine the efficacy and toxicity of hypofractionated radiotherapy (hypo-RT) plus concurrent chemotherapy with or without consolidation immunotherapy for local advanced non-small cell lung cancer patients (LA-NSCLC). Materials/

Methods: This phase II, single-arm study enrolled patients with unresectable, stage IIIA/B/C NSCLC. All patients were aged 18–75 years with an Eastern Cooperative Oncology Group performance status of 0–1. Patients were treated with hypo-RT (30Gy in 6 daily fractions) followed by hypofractionated boost (hypo-boost) (30Gy in 6 daily fractions), with an interval of 4 weeks between two courses. Concurrent chemotherapy consisted of weekly docetaxel 25 mg/m² and cisplatin 25 mg/m². Consolidation PD1/PD-L1 inhibitors were recommended for those without disease progression or persistent grade(G)2+ toxicities following radiotherapy. The primary endpoint was progression-free survival (PFS). The secondary endpoints included overall survival (OS), objective response rate (ORR) and toxicities. Survival was calculated from the start of radiotherapy. Toxicities was graded according to CTCAE V5.0.
Results: Between July 2020 and January 2023, a total of 104 patients were enrolled. As of data cutoff (December 31, 2023), the median follow-up was 24.0 months. 100 (98.1%) patients completed hypo-RT and hypo-boost per protocol. 49 (47.1%) patients received consolidation immunotherapy following hypo-RT and hypo-boost. The ORR of the whole cohort was 90.2%. The median PFS was 23.7 months (95% confidence interval [CI], 19.0-28.4 months). The 1- and 2-year PFS rates were 85.4% (95% CI, 78.8%-92.5%) and 48.9% (95% CI, 39.0%-61.1%), respectively. The median OS had not been reached at the time of the last follow-up. The 1- and 2-year OS were 92.2% (95% CI, 87.2%-97.6%) and 63.3% (95% CI, 53.4%-75.0%), respectively. In subgroup analysis, patients receiving consolidation immunotherapy exhibited a significantly longer PFS compared to those who did not (median PFS, not reached vs. 20.0 months, p=0.044). There were 12(11.5%) and 3(2.9%) patients experiencing G2 and G3 pneumonitis, respectively. G2 and G3 esophagitis were observed in 13 (12.5%) and 4 (3.8%) patients, respectively. No G4+ toxic events occurred during follow -up.
Conclusion: Hypo-RT and hypo-boost delivered at 5Gy per fraction to a total dose of 60Gy, in combination with concurrent weekly chemotherapy, has the potential to produce favorable local control and survival outcomes in patients with LA-NSCLC, while exhibiting moderate radiation-induced toxicity. (ClinicalTrials.gov identifier: NCT04212052).