Firstly, CTLA-4 inhibitors can reduce the anti-proliferative effect on activated T-cells. Secondly, inhibiting the PD-1 signalling pathway (Fig. 1) stimulates the antitumoral immune response, which also increases the number of activated T cells.
This is made possible due to the reduction of apoptosis of regulatory T-cells and the induction of apoptosis of antigen-specific T-cells through the PD-1 signalling pathway.