[Immunological Effect of Hydrogen Gas-Hydrogen Gas Improves Clinical Outcomes of Cancer Patients]

Abstract

It has been reported that PD-1-expressing CD8+ T cells in the peripheral blood of cancer patients are associated with poor cancer prognosis. In addition, these cells are in a state of energy shortage caused by mitochondrial dysfunction with a low level of PGC-1a. Recently, hydrogen gas was reported to activate PGC-1a, leading to the enhancement of mitochondrial activity. In the present study, we investigated whether hydrogen gas influences the proportion of PD-1+ CD8+ T cells in the peripheral blood of 55 Stage IV colorectal carcinoma patients. We found that the proportion of terminal PD-1+ CD8+ T cells was an independent factor for poor prognosis. We also found that the proportion of terminal PD-1+ CD8+ T cells was reduced in 35 out of 55 patients(63.6%)and was increased in 39 out of 55 patients(70.9%)after treatment with hydrogen gas. The ratio of the terminal PD-1+ CD8+ T cells after hydrogen gas treatment to that before hydrogen gas treatment(terminal PD-1+ CD8+ T cell ratio)was found to be an independent factor predicting PFS and OS. Out of another 26 patients treated with nivolumab, 14 patients treated with a combined therapy of hydrogen gas and nivolumab showed a significantly longer OS than the remaining 12 patients who were treated with nivolumab alone. These results suggest that hydrogen gas improves the prognosis of cancer patients by reducing the proportion of terminal PD-1+ CD8+ T cells.