IFNG and neoplasm: These observations led to a TME classification of tumor-immune phenotypes involving three major classes of tumors: ‘immune deserts’ tumors (or ‘cold tumors’), showing no immune cell infiltration; ‘immune-excluded’ tumors (also cold) with immune cells at the tumor margins; and ‘inflamed’ tumors (or ‘hot’ tumors), showing immune infiltrates in the tumor core that can have IFNγ expression signatures [19,20,21] (Figure 1).