Method for diagnosing human T-cell leukemia virus type 1 (HTLV-1)-related disease

A method for treating a human T cellular leukemia virus type 1 (HTLV-1) related disease, which is acute adult T-cell leukemia (acute ATL), in a subject suspected of having acute ATL or at risk of developing acute ATL, comprising the steps of:

• (1) measuring an amount of tumor necrosis factor receptor 2 (TNFR2) in blood samples taken from the subject suspected of having acute ATL or at risk of developing acute ATL at two or more different time points before applying a therapy for treating acute ATL;
• (2) selecting the subject as a treatment subject when the amount of TNFR2 measured at a later time point before applying the therapy for treating acute ATL is higher than the amount of TNFR2 measured at an earlier time point before applying the therapy for treating acute ATL and higher than a blood concentration threshold of 7.6-10.3 ng/ml;
• and
• (3) applying the therapy for treating acute ATL to the treatment subject, wherein the therapy is a chemotherapy and/or a non-chemotherapy, and wherein the non-chemotherapy is an allogeneic hematopoietic stem cell transplantation, a T cell therapy, a cancer vaccine therapy or a cytokine therapy.