Real-world utilization of PD-1/PD-L1 inhibitors with palliative radiotherapy in patients with metastatic non-small-cell lung cancer

Background Programmed cell death protein 1 (PD-1) blockade combined with radiotherapy may be a promising strategy to improve the prognosis of patients with advanced non-small-cell lung cancer (NSCLC). However, the optimum radiotherapy scheme, timing, and location have not been fully determined. Methods We conducted a retrospective study of 57 patients receiving PD-1/PD-ligand 1 (PD-L1) inhibitors with radiotherapy for metastatic NSCLC in Zhejiang Cancer Hospital between June 2017 and December 2019. Data on overall survival (OS), progression-free survival (PFS), treatment response and adverse events were collected. Comparisons based on type of radiation, timing of radiotherapy and number of irradiated lesions were performed. Results The median OS was 25.9 (95% CI: 18.4-33.4) months, and the median PFS was 10.3 (95% CI: 8.9-11.8) months. The in-field and out-of-field overall response rates were 45.2% and 32.1%, respectively. Multisite radiotherapy was associated with longer PFS than single-site radiotherapy (19.50 vs. 9.10 months, P = 0.017). Furthermore, immunotherapy with concurrent radiotherapy tended to have superior outcomes compared with immunotherapy with sequential radiotherapy (OS: NR vs. 20.87 months, P = 0.079; PFS: 11.4 vs. 9.0 months, P = 0.153), as did immunotherapy with stereotactic radiotherapy compared with traditional radiotherapy (OS: 30.6 vs. 25.9 months, P = 0.840; PFS: 11.1 vs. 9.9 months, P = 0.803). The incidence of treatment-related adverse events (AEs) was 61.4%, but only 5.3% of patients experienced grade 3 AEs. Conclusions The combination of immunotherapy and radiotherapy demonstrated favourable survival and good tolerability in Chinese patients with advanced NSCLC.