Serum soluble interleukin-2 receptor as a potential biomarker for immune-related adverse events

Abstract

Background/Aim: Biomarkers for immune-related adverse events (irAEs) induced by immune checkpoint inhibitors (ICIs) are required. We encountered a patient whose skin irAE fluctuated in parallel with serum soluble interleukin- 2 receptor (sIL-2R). Patients and Methods: We examined 15 patients with cancer who received ICIs. Serum sIL-2R levels before and during ICI treatment were measured. The sIL-2R levels of preserved serum samples from another five patients who developed grade 3 irAEs were measured. Results: Twelve patients showed no significant changes in sIL-2R levels during ICI treatment. Baseline serum sIL-2R levels in three patients increased beyond the normal range before the second cycle. These three patients had grade ≥2 irAEs at the second cycle treatment visit, supporting our hypothesis. Furthermore, at diagnosis of irAEs, the sIL-2R levels of all preserved samples from patients with grade 3 irAEs were significantly elevated. Conclusion: Serum sIL-2R is a promising biomarker for the diagnosis of irAEs.