Indoleamine 2,3-Dioxygenase Activity Is Increased in Myelodysplastic Syndrome Patients

Kimihiro Yamaguchi, Soranobu Ninomiya, Takuro Matsumoto, Nobuhiko Nakamura, Hiroshi Nakamura, Junichi Kitagawa, Nobuhiro Kanemura, Takeshi Hara, Suwako Fujigaki, Yasuko Yamamoto, Kuniaki Saito, Hisashi Tsurumi, Masahito Shimizu

Research output: Contribution to journalArticlepeer-review


Tryptophan (TRP) metabolism via the indoleamine 2,3-dioxygenase (IDO) subset of the kynurenine (KYN) pathway is one of the most important mechanisms of immune escape in cancer. TRP is converted into several biologically active KYN metabolites. However, the role of KYN metabolic products and related enzymes has not been clarified in patients with hematological malignant tumors. Here, we examined the serum concentrations of TRP, KYN, and the KYN metabolites kynurenic acid, anthranilic acid, and 3-hydroxyanthranilic acid in 157 patients stratified into five different hematological malignant tumors. KYN was the most abundant product of the TRP metabolic pathway among all five diagnostic categories. Serum KYN was increased in myelodysplastic syndrome (MDS) patients. The KYN/TRP ratio was significantly higher in MDS patients than in acute myeloid leukemia patients. In conclusion, IDO activity is increased in MDS patients, and IDO inhibitors might represent a new therapeutic approach for MDS treatment.

Original languageEnglish
Pages (from-to)77-85
Number of pages9
Issue number2
Publication statusPublished - 12-2020

All Science Journal Classification (ASJC) codes

  • Hematology


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