As a final consideration, OV infection may prove to be more efficacious in tumours with an acquired impairment of IFNγ signalling (e.g. through mutation of the JAK-STAT pathway), whereas CAR T-cell therapy may provide a more attractive option for patients whose tumours have lost MHC class I expression (e.g. due to β2-microglobulin mutations). The gene discussed is IFNG; the disease is infection.