[Chemotherapy-induced peripheral neuropathy and sex hormones]

Chemotherapy-induced peripheral neuropathy (CIPN) frequently develops following treatment of cancer with cytotoxic chemotherapeutics, such as taxanes, platinum-containing agents and vinca alkaloids, and leads to impairment of patients' QOL and dose limitation or cessation of chemotherapy in the worst-case scenario. We have demonstrated that extracellular release of high mobility group box 1 (HMGB1), a nuclear protein, plays a critical role in the developmental process of CIPN, and that thrombomodulin alfa (TMα) capable of degrading HMGB1 in a thrombin-dependent manner prevents CIPN development. Our retrospective cohort study in female patients with breast cancer or gynecological cancer undergoing paclitaxel-based chemotherapy has shown that postmenopausal estrogen decline is a risk factor for the development or aggravation of CIPN. We have also demonstrated that ovariectomy aggravates CIPN in laboratory animals treated with paclitaxel, which is prevented by estrogen supplementation or treatment with TMα. On the other hand, there is evidence from animal studies for inhibition of CIPN by progesterone and of neuropathic pain by androgen. Together, different sex hormones including estrogen may function to limit the development of CIPN, while age-related decline of sex hormones could be a risk for CIPN development. Our study to clarify the effects of sex hormones on HMGB1 behavior during the developmental process of CIPN is still in progress, but we nonetheless propose that TMα capable of inactivating HMGB1 is useful in preventive intervention for cancer patients with high risk of CIPN, e.g., postmenopausal females.