Prevalence of human T-lymphotropic virus type I in patients with psoriasis and its effect on treatment choice: A multicenter observational study.

Biologics have benefited psoriasis patients due to their high therapeutic efficacy. In 2019, the Japanese Dermatological Association has revised Guidance for the Use of Biologics in Psoriasis [ [1] Saeki H. Terui T. Morita A. Sano S. Imafuku S. Asahina A. et al. Biologics Review Committee of the Japanese Dermatological Association for Psoriasis: Chair: O. Mamitaro, Japanese guidance for use of biologics for psoriasis (the 2019 version). J. Dermatol. 2020; 47: 201-222 Crossref PubMed Scopus (52) Google Scholar ] for the safe use of biologics. It recommended screening tests for latent infections such as tuberculosis and viral hepatitis before starting the use of biologics. Human T-lymphotropic virus type I (HTLV-1) is a human retrovirus [ [2] Forlani G. Shallak M. Accolla R.S. Romanelli M.G. HTLV-1 infection and pathogenesis: new insights from cellular and animal models. Int. J. Mol. Sci. 2021; 22 Crossref Scopus (13) Google Scholar ]. Some individuals with HTLV-1 infection develop adult T-cell leukemia-lymphoma (ATL) [ [3] Schierhout G. McGregor S. Gessain A. Einsiedel L. Martinello M. Kaldor J. Association between HTLV-1 infection and adverse health outcomes: a systematic review and meta-analysis of epidemiological studies. Lancet Infect. Dis. 2020; 20: 133-143 Abstract Full Text Full Text PDF PubMed Scopus (96) Google Scholar ]. In Japan, HTLV-1 carriers are more common in the southwestern area [ [4] Satake M. Yamaguchi K. Tadokoro K. Current prevalence of HTLV-1 in Japan as determined by screening of blood donors. J. Med. Virol. 2012; 84: 327-335 Crossref PubMed Scopus (150) Google Scholar ]. Serum anti-HTLV-1 antibody testing is listed as one of the screening tests in the Japanese guidance on biologics [ [1] Saeki H. Terui T. Morita A. Sano S. Imafuku S. Asahina A. et al. Biologics Review Committee of the Japanese Dermatological Association for Psoriasis: Chair: O. Mamitaro, Japanese guidance for use of biologics for psoriasis (the 2019 version). J. Dermatol. 2020; 47: 201-222 Crossref PubMed Scopus (52) Google Scholar ], but there is no description about the management of HTLV-1–positive patients. To date, the evidence has been very limited. In rheumatoid arthritis (RA), a chronic systemic inflammatory disease similar to psoriasis, several case series have reported the prevalence of HTLV-1 carrier status [ [5] Iwamoto N. Araki T. Umetsu A. Takatani A. Aramaki T. Ichinose K. et al. The Association of Increase of Human T-Cell Leukemia Virus Type-1 (HTLV-1) Proviral Load (PVL) With Infection in HTLV-1-Positive Patients With Rheumatoid Arthritis: A Longitudinal Analysis of Changes in HTLV-1 PVLs in a Single Center Cohort Study. Front. Immunol. 2022; 13887783 Crossref Scopus (0) Google Scholar ]. HTLV-1 carriers are reportedly less responsive to tumor necrosis factor (TNF)-α inhibitors than non-carriers [ [6] Suzuki T. Fukui S. Umekita K. Miyamoto J. Umeda M. Nishino A. et al. Brief report: attenuated effectiveness of tumor necrosis factor inhibitors for anti-human T lymphotropic virus type I antibody-positive rheumatoid arthritis. Arthritis Rheuma. 2018; 70: 1014-1021 Crossref PubMed Scopus (13) Google Scholar ]. Although the sample sizes were limited, these research studies suggested that treatment with TNF-α inhibitors does not affect the development of ATL. Almost no information is available about biologic therapy for patients with psoriasis and HTLV-1 carrier status. Therefore, a multicenter retrospective study was conducted to characterize the prevalence of HTLV-1 carrier status in patients with psoriasis and how they are currently being treated.