Biomarkers associated with side effects of checkpoint inhibitors are being studied as a way to assess the risk of irAEs and as an aid in the early identification of such complications.
In one report, ipilimumab-treated patients with melanoma who developed colitis had higher on-treatment serum concentrations of interleukin 17 (IL-17) compared with those without colitis. In this study, there was also a temporal relationship between colitis symptoms and elevations in IL-17 in several patients.
●In another study, gene expression profiling was performed on whole blood samples from patients with melanoma treated in two phase II clinical trials of ipilimumab.
Differences in gene expression at baseline (including immunologically relevant genes) were observed comparing patients who ultimately developed gastrointestinal toxicity with those who did not. There were increases in expression of immunologically-related genes during ipilimumab treatment that were also seen to a greater degree in patients who ultimately developed gastrointestinal toxicity.
●Other studies have examined peripheral blood counts to assess whether eosinophilia (often seen during ipilimumab treatment) is associated with adverse events. In one retrospective, multi-institution review, the degree of eosinophilia was associated with the development of an irAE during ipilimumab treatment. Additional study is necessary, but this is consistent with other series, in which skin rashes have been associated with eosinophilia.