Stereotactic body radiation therapy enhances therapeutic efficacy of immune checkpoint inhibitors by promoting the releasing of interferon-γ and interleukin-2

To explore whether stereotactic body radiation therapy (SBRT) could promote the release of serum interferon-γ (IFN-γ) and interleukin-2 (IL-2), as well as the prognostic value of IFN-γ in patients receiving SBRT combined with immune checkpoint inhibitors (ICIs) treatment. 63 patients with metastatic non-small cell lung cancer (NSCLC; 34 cases) or metastatic gastric cancer (GC; 29 cases) receiving chemotherapy plus ICIs treatment were enrolled in the present study. All the cases were classified into two groups according to receiving SBRT or not. The progression-free survival (PFS) and overall survival (OS) were further analyzed by KM curve. The serum IFN-γ and IL-2 values of patients who receiving SBRT and those did not receiving SBRT were compared by t-test. The correlation between the indicators and programmed cell death ligand 1 (PD-L1) was analyzed by Spearman test. The prognosis of the IFN-γ recovery group after treatment was significantly better than that non-recovery group; the serum IL-2 and IFN-γ levels of the patients receiving SBRT were significantly higher than those of the non- receiving group; serum IFN-γ and IL-2 values were positively correlatie with PD-L1 expression in NSCLC and GC tissues. SBRT can promote the release of IL-2 and IFN-γ, and the survival of patients with IFN-γ recovery after treatment is significantly improved, so IFN-γ can predict the efficacy of gastric and NSCLC patients.