The safety and efficacy of immune checkpoint inhibitors in patients with advanced cancers and pre-existing chronic viral infections (Hepatitis B/C, HIV): a review of the available evidence

The safety and efficacy of immune checkpoint inhibitors in patients with advanced cancers and pre-existing chronic viral infections (Hepatitis B/C, HIV): a review of the available evidence: Over the last decade immunotherapy has revolutionized the treatment of many cancers, especially with the better understanding of molecular biology and immunology. Programmed death 1 (PD-1) is an inhibitory cell-surface receptor expressed on the surface of T cells, B cells, and natural-killer cells. The effector functions of T cells that express PD-1 in the tumor microenvironment can be downregulated upon activation by its ligands (PD-L1 or PD-L2), which are expressed by the tumoral cells. Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a B7/CD28 protein receptor that functions as an immune checkpoint, inhibiting T cell functions.