Several studies demonstrated that cyst(e)inase inhibited cancer growth and improved survival in several cancer mouse models.14,18,19 Recently, Kshattry et al.20 reported that cyst(e)inase in combination with auranofin, a thioredoxin reductase inhibitor, had a synergistic antitumor effect on resistant pancreatic cancer xenografts. This evidence concerns the gene PRDX5 and cancer.