PD-1 checkpoint pathway
Definition An immune pathway which, in absence of malignancy, downregulates T cell activation, keeping nascent T-cell responses in check, reducing the risk of T cells developing autoimmune responses to normal (self) antigens, cells and tissue.
During tumourigenesis, cancer cells may exploit these co-inhibitory pathways to resist both detection or avoid elimination by the immune system. An evolving anti-cancer treatment strategy is administration of anti-PD-1 antibodies to patients with cancer, which upregulates T cell activation.
Results have been very encouraging, especially when combined with ipilimumab (anti-CTLA-4); larger trials are ongoing.
References Clin Pharmacology & Therapeutics (2014); 96 2, 214–223.
Science 2013; 342:1432-33.