Nivolumab-Induced Pneumonitis in a Patient With Urothelial Cancer.

The introduction of immune checkpoint inhibitors has revolutionized cancer treatment. These drugs function by inhibiting the binding of programmed death-1 (PD-1) and its ligand, PD-L1, which inhibits the immune response against cancer cells. Nivolumab is a PD-1 inhibitor that specifically targets the PD-1 pathway.