Vildagliptin is a dipeptidyl peptidase-4 (CD26) inhibitor. CD26 activates serine proteases in immune/inflammatory cells. Vildagliptin also inhibits dipeptidyl-peptidase 8 (DPRP1) and dipeptidyl-peptidase 9 (DPRP2), which have been correlated to T cell activation and immune function, as well as diabetes and cancer regulation.