Through qRT-PCR, CpG methylation, and repressive histone abundance experiments, TIGIT was found poorly expressed in primary breast cancer and adjacent non-cancerous tissues because its CpG islands at the promoter level were mostly hypermethylated (80-70%), while CpG islands of PD-L1 and LAG3 promoter were demethylated at 100% and 80-90%, respectively (130). The gene discussed is TIGIT; the disease is breast cancer.