TIGIT and neoplasm: These include: (1) endogenous T-cell suppression; (2) acquired expression of the checkpoint molecule TIGIT in CTLs; (3) acquired TIGIT expression and reduced expression of HLA-II molecules in tumor cells; (4) increased MDSCs and neutrophils; and (5) elevated soluble forms of checkpoint molecules sPD-L1, sTIM3, s4-1BB, and the receptors sIL-2R and sTNFRII, as well as chemokines CCL4, CXCL9, and CXCL13.