ICOS/ICOSL pathway activation has been observed in multiple cancer types including melanoma [60], multiple myeloma [61], breast [62], ovarian [63], gastric [64], liver [65], Merkel cell carcinoma [66], angioimmunoblastic T‐cell lymphoma [67], and colorectal cancers [68]. The gene discussed is ICOSLG; the disease is plasma cell myeloma.