[Indoleamine 2, 3-dioxygenase activity during chemotherapy or trastuzumab therapy in patients with breast cancer].

We evaluated the significance of indoleamine 2, 3-dioxygenase (IDO) in breast cancer patients during chemotherapy or trastuzumab therapy. IDO activity can be measured by the tryptophan(Trp)/kynurenine(Kyn) ratio. Trp and Kyn were measured by high-performance liquid chromatography(HPLC). The correlations between the Trp/Kyn ratios in the chemotherapy group and the trastuzumab therapy group with respect to pre-chemotherapies or post-chemotherapies were studied. The Trp/Kyn ratio of the chemotherapy group in the post-epirubicin and cyclophosphamide(EC) chemotherapy phase and in the post-weekly paclitaxel(wPTX) chemotherapy phase was lower than that in the pre-chemotherapy phase. In addition, the Trp/Kyn ratio in the chemotherapy group was significantly lower than that in the hormone therapy group in the post-EC chemotherapy phase and in the post-wPTX chemotherapy phase. There were no significant changes in the Trp/Kyn ratio in the trastuzumab therapy group in each phase. These results suggest that trastuzumab therapy may be less invasive than chemotherapy for breast cancer patients.