According to the University of Tokyo, IDO1 is an enzyme that metabolizes the essential amino acid tryptophan and is known to be expressed in the placenta as a molecule that suppresses the immune response to a non-self-born foetation during pregnancy.It has been found to be expressed in human tumor tissues and is attracting attention as a target for immunotherapy.

　The research group examined the tumor tissue of dog organs from specimens removed by surgery and found that IDO1 was overexpressed. Of the 13 canine tumors, the strongest expression of bladder cancer has been confirmed.

　Bladder cancer in dogs has a high metastasis rate, and the survival rate after surgical treatment is said to be about one year.It is said that even if it is combined with medical treatment such as anticancer drugs, it survives for only about 1 years, and it is counted as one of the worst prognosis among dog tumors.

　The research group proceeded with verification in mice transplanted with a canine bladder cancer cell line and found that IDO1 inhibitors activate antitumor immune cells and have a therapeutic effect.Based on this finding, clinical trials were started at the Animal Medical Center attached to the Graduate School of Agriculture and Life Sciences, the University of Tokyo.

　Immunotherapy is attracting attention as the fourth cancer treatment method after surgery, anticancer drugs, and radiation.The research group hopes that inhibition of IDO4 at the same time as inhibition of molecules that suppress the action of antitumor T cells that attack tumors could establish new treatments for cancer.

Paper information:[The Journal of Veterinary Medical Science] Detection of indoleamine 2,3-dioxygenase 1–expressing cells in canine normal and tumor tissues