Pembrolizumab

Checkpoint blockade rather than direct cytotoxicity is how pembrolizumab acts: the monoclonal antibody binds programmed cell death protein 1 and prevents the inhibitory signal that tumours exploit to switch off cytotoxic T cells. Releasing that brake restores antitumour immunity, so the therapeutic effect is produced by the patient's own lymphocytes rather than by the drug. The antibody belongs to the antineoplastic and immunomodulating group, and its elimination half-life of roughly 26 days reflects the slow clearance typical of immunoglobulin therapeutics, allowing dosing intervals measured in weeks. Because the mechanism removes an immune restraint, the adverse effects characteristic of the class are autoimmune in nature.