The exploratory case-control study on prediction of immune checkpoint inhibitor-induced thyroiditis by human leukocyte antigen types

2558 Background: Given the function of human leukocyte antigen (HLA) in immunity, variation of the HLA type could affect the development of immune-related adverse events (irAEs) that is induced by immune checkpoint inhibitors (ICIs). In this study, we examined whether HLA types of cancer patients could be a marker for the development of irAE thyroiditis. Methods: In the present case-control study, we randomly selected 20 cancer patients who received ICIs and developed thyroiditis (irAE thyroiditis group) and 51 who did not develop thyroiditis (No irAE thyroiditis group). The 51 patients were subdivided into 31 who did not develop any irAEs (No irAEs group) and 20 who developed irAEs other than thyroiditis (irAEs other than thyroiditis group). HLA types were classified at the amino acid sequence level (Field 2 resolution). Frequency of the HLA types of each group was compared. Results: There was no significant difference in HLA type prevalence, comparing the irAE thyroiditis group and the No irAE thyroiditis group. When comparing the irAE thyroiditis group with the No irAEs group, the irAE thyroiditis group had significantly higher HLA-X, HLA-Y, and HLA-Z (Tentative names are used here, and actual HLA types will be announced at the time of publication). This result suggested that irAEs other than thyroiditis in the control group could be noise. HLA-X had a specificity of 96.8% for the development of irAE thyroiditis. HLA-Y had a sensitivity of 80.0%. Patients carrying both HLA-X and HLA-Y had the highest specificity of 100.0%. There was a significant difference in frequency of HLA-Y between irAEs other than the thyroiditis group and the No irAEs group. HLA-Y may be a universal marker for any irAEs. On the other hand, HLA-X is a specific marker for thyroid irAE. The median time of onset of irAE thyroiditis in all patients was 72 days after ICI administration. Patients with both HLA-X and HLA-Y tended to have an earlier onset with a median onset time of 53 days. Conclusions: We found an association between specific HLA types and the development of irAE thyroiditis. The present study indicates that HLA types could be a predictive marker for the development of irAE thyroiditis.