Final answer:
Nivolumab and Pembrolizumab work as immune checkpoint inhibitors targeting PD-1 on T cells, preventing its interaction with PD-L1/PD-L2 on tumor cells and enabling an immune response against cancer.
Step-by-step explanation:
The mechanism of action of Nivolumab and Pembrolizumab involves immune checkpoint inhibition. These drugs are monoclonal antibodies that target the programmed cell death protein 1 (PD-1), a checkpoint protein on T cells. By binding to PD-1, they prevent its interaction with PD-L1 and PD-L2, which are expressed on tumor cells and other cells within the tumor microenvironment. When PD-1 engages with its ligands, it delivers an inhibitory signal that reduces the proliferation of T cells in lymph nodes, limiting their immune response. Nivolumab and Pembrolizumab 'unmask' the cancer cells by disrupting this interaction, thus allowing T cells to recognize and attack cancer cells.