2022 年 39 巻 4 号 p. 448-452
Human T–cell leukemia virus type I (HTLV–1) causes two diseases in some infected individuals : HTLV–1 associated myelopathy (HAM), a chronic inflammatory disease of the spinal cord, and adult T cell leukemia–lymphoma (ATL), a neoplastic disease. The pathogenesis of HAM is thought to center on the formation and maintenance of chronic inflammatory foci caused by an excessive immune response centered on HTLV–1–infected T cells infiltrating neural tissues, and clarifying the mechanism of pathogenesis is important for personalized medicine based on the pathophysiology of HAM. Based on real–world data obtained from HAM–net, HAM is classified into three major disease activity categories. Furthermore, based on these evidences, the “HAM Clinical Practice Guidelines 2019” established new treatment algorithms, including disease activity classification criteria for HAM and stratified treatment accordingly. More recently, prospective cohort data from HAM–net revealed that the life expectancy (standardized death ratio) of HAM is poor and, surprisingly, ATL is the leading cause of death in HAM patients. These results suggest the importance of medical care based on risk assessment for the development of ATL in patients with HAM. In the future, it will be important to correctly understand the characteristics and status of HTLV–1–infected cells when treating patients with HAM, and further progress in personalized medicine based on biomarkers that reflect the characteristics of each patient is expected.
