PD-L2 expression as a potential predictive biomarker for the response to anti-PD-1 drugs in patients with non-small cell lung cancer

Background/Aim: To investigate the role of programmed cell death-ligand 2 (PD-L2) expression as a predictive biomarker for response to anti-programmed cell death-1 (PD-1) drugs in patients with non-small cell lung cancer (NSCLC). Patients and Methods: Ten patients who had undergone curative lung resection and received the anti-PD-1 drugs for the recurrence were enrolled. The cut-off value for PD-L2 (antibody clone 176611) expression on tumor cells was set at 50%. Tumor response was evaluated according to immune-related response criteria. Results: Seven patients (70.0%) were positive for PD-L2. The response rates were 28.6% (2/7) and 33.3% (1/3) in patients with PD-L2-positive and PD-L2-negative NSCLC, respectively. Disease control was obtained in 2 patients despite the programmed cell deathligand 1 (PD-L1)-negativity (antibody clone 22C3: 0%, antibody clone SP142: 0%), and these tumors expressed PDL2 (=1%). Conclusion: PD-L2 expression may be a target of immunotherapy in patients with PD-L1-negative NSCLC.