We first tested the potential association between PD-L2 expression level and clinical outcome of NSCLCs using the Online Survival Analysis Software (Gyorffy 2024), and found that the expression level of PD-L2 was inversely associated with overall survival (OS) in lung cancer patients (Fig. 1a, Supplementary Fig. 1), though the expression level of RGMB was not associated with the clinical prognosis of NSCLC patients (Supplementary Fig. 2). Here, RGMB is linked to lung cancer.