How do immune checkpoint inhibitors function in cancer therapy?

Immune checkpoint inhibitors are a class of drugs that play a crucial role in cancer therapy by blocking specific proteins that can inhibit the immune system's ability to attack cancer cells. Cancer cells can exploit certain checkpoints, which are mechanisms that regulate the immune response, to turn off T cells, thereby avoiding immune detection and destruction.

The correct choice indicates that these inhibitors function by stopping cancer cells from turning off T cells. By doing so, immune checkpoint inhibitors enhance the ability of T cells to recognize and destroy cancer cells. This mechanism is particularly important in activating the immune response against tumors that have successfully evaded detection due to the activation of these inhibitory checkpoints.

The other options do not accurately reflect the function of immune checkpoint inhibitors. For instance, promoting tumor growth contradicts their purpose as cancer therapies, which aim to inhibit tumor progression. Preventing T cells from being activated directly opposes the desired effect of these treatments, which is to enhance T cell activation. Additionally, enhancing tumor blood supply does not pertain to the mechanism of action of immune checkpoint inhibitors, as these drugs directly influence the immune response rather than targeting tumor vasculature.