Long-term remission of VEXAS syndrome achieved by a single course of CHOP therapy: A case report.

We herein describe the case of a 52-year-old male patient who presented with fever, arthritis, and neutrophilic dermatosis in 2013 and subsequently experienced macrophage activation syndrome treated with high-dose glucocorticoid therapy. Due to the persistent symptoms refractory to several immunomodulatory and immunosuppressive (IS) drug therapies with dapsone, methotrexate, tacrolimus, infliximab (IFX), and tocilizumab (TCZ), he received prednisolone (PSL) ≥20 mg/day to suppress disease activity. In 2017, Epstein-Barr virus (EBV)-associated haemophagocytic lymphohistiocytosis (HLH) was diagnosed and initially treated with immunochemotherapy consisting of dexamethasone, cyclosporine (CyA), and etoposide (ET). Because of the suboptimal response to the initial therapy, cytoreduction therapy consisting of CHOP (combination chemotherapy consisting of cyclophosphamide, doxorubicin, vincristine, and PSL) was administered. This regimen improved the EBV-associated HLH. Later, the patient's condition stabilised with methylprednisolone 1 mg/day and CyA 100 mg/day. In 2022, ubiquitylation-initiating E1 enzyme (UBA1) variant analysis using Sanger sequencing of peripheral blood leukocytes detected a previously reported somatic variant (NM_003334.3: c.118-1G>C), confirming the diagnosis of vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome. The clinical course in the present case suggested the possibility that CHOP could be a potential treatment option for VEXAS syndrome, in the pathophysiology of which the expansion of clones with UBA1 variant seems to play a pivotal role.