TIGIT Immune Checkpoint Molecule for Drug Development: TIGIT (T cell immunoglobulin and ITIM domain), also known as VSig9, Vstm3, or WUCAM, is an inhibitory receptor member of the CD28 family. TIGIT binds to CD155 (PVR or Necl-5) with high affinity and weakly interacts with CD112 (PVRL2, nectin-2). TIGIT also competes with other counterparts, CD266 (DNAM-1) or CD96, to exert its immunosuppressive effects.