Here, we demonstrated that TAM exosome transmission and TNF‐α stimulation in the tumour microenvironment induce RIME upregulation in tumour cells, which constitutively upregulates the expression of the immune checkpoint markers PD‐L1/IDO‐1 and results in antitumour T‐cell inactivation and a reduced response to anti‐PD‐1 mAb therapy. Here, IDO1 is linked to neoplasm.