Human
T-cell leukemia virus type I (HTLV-1)-associated
myelopathy/
tropical spastic paraparesis (HAM/TSP) is a rare inflammatory disease causing unremitting and progressive
neurological disorders, such as
spastic paraparesis,
neurogenic bladder, and sensory disturbance of the lower extremities. Although there is no cure, immune-modulating agents such as
corticosteroids are most widely used to slow
disease progression.
Biomarkers for the clinical assessment of HAM/TSP should be identified because the prediction of functional prognosis and the assessment of treatment efficacy are challenging due to the slowly progressive nature of the disease. The lack of surrogate
biomarkers also hampers clinical trials of new drugs. This review summarizes
biomarker candidates for the clinical assessment of patients with HAM/TSP. Most of the reported
biomarker candidates are associated with viral components or inflammatory mediators because immune dysregulation provoked by HTLV-1
infection is thought to cause chronic
inflammation and damage the spinal cord of patients with HAM/TSP. Although information on the diagnostic accuracy of most of the reported
biomarkers is insufficient, several molecules, including inflammatory mediators such as CXCL10 and
neopterin in the cerebrospinal fluid, have been suggested as potential
biomarkers of functional prognosis and treatment response. Several clinical trials for HAM/TSP are currently underway, and we expect that these studies will provide not only evidence pertaining to treatment, but also novel findings regarding the utility of
biomarkers in this disease. The establishment of clinical
biomarkers will improve patient care and promote the development of
therapies for HAM/TSP.