Soluble PD‐L1 predicts tumor response and immune‐related adverse events in patients with advanced melanoma treated with anti–PD‐1 antibodies

Abstract

Immune checkpoint inhibitors (ICIs) bring prognostic benefits to patients with malignancies. However, there is a substantial number of patients whose lesions are not improved by ICIs. In addition, ICIs may cause immune‐related adverse events (irAEs), which could lead to an unfavorable prognosis with fatal consequences. Therefore, we conducted a retrospective study to evaluate the utility of circulating sPD‐L1 (soluble programmed cell death 1 ligand 1) as a biomarker in patients with advanced melanoma treated with anti–PD‐1 (programmed cell death 1 protein) antibodies. Sera from 31 consecutive patients were prospectively collected before and after anti–PD‐1 antibody treatment and the serum level of sPD‐L1 was evaluated. We found that high sPD‐L1 levels before treatment were associated with better prognosis, and this association was observed only in patients with a low tumor burden. We also found that sPD‐L1 levels were elevated in patients who developed severe irAEs after treatment, and the patients with severe irAEs had significantly higher fluctuations in sPD‐L1 (delta sPD‐L1) than those without severe irAEs. Our study suggests that serum sPD‐L1 level is a useful biomarker to predict tumor response and irAE development in patients with advanced melanoma treated with anti–PD‐1 antibodies.