The phenomenon of hyperprogression has been previously recapitulated in a mouse model of T-cell NHL, demonstrating that when the tumor cells are T cells themselves, immunotherapy with ICIs can actively promote tumor progression, implying that in some T-cell malignancies, as in ATLL, PD-1 functions as a tumor suppressor [163, 164]. The gene discussed is PDCD1; the disease is adult T-cell leukemia/lymphoma.