CD4 and tropical spastic paraparesis: Importantly, mogamulizumab, which is approved for two types of cutaneous T‐cell lymphoma treatment,[93] is also considering for the therapy of T‐cell leukemia virus type‐1 (HTLV‐1)‐associated myelopathy/tropical spastic paraparesis.[94] During this disease, HTLV‐1‐infected CD4 T cells penetrate through blood blood‐brain barrier to the spinal cord and stimulate the release of CXCL10 by astrocytes, which recruits more CXCR3‐positive lymphocytes into CNS.[95] Among clinical outcomes of mogamulizumab administration in patients with HTLV‐1‐associated myelopathy, Sato et al.