Efficacy of ICIs may be restricted due to the lack of neoantigens presented on cancer cells, defects in expression of the MHC or in other components of the antigen-presenting machinery in cancer cells, development of resistant tumour subclones and lack of T-cells in the immunosuppressive microenvironment of the tumour.6 ICIs are usually administered repeatedly every few weeks in the outpatient setting. The gene discussed is HLA-C; the disease is cancer.