In line with our data of activated (CD4+CD38+HLADR+) T cells associated with irAE, Subudhi and coworkers showed that expansion of specific CD8+ Tcell clones preceded the development of severe irAE and identified CD8+ T cells as a potential predictive biomarker for irAEs in patients with metastatic prostate cancer under ipilimumab therapy [16]. The gene discussed is CD38; the disease is metastatic prostate carcinoma.