Takayasu arteritis is a chronic large-vessel vasculitis affecting the aorta and its major branches. Biologic therapies such as tumor necrosis factor inhibitors and tocilizumab are commonly used in patients with refractory or relapsing disease. However, there is limited evidence regarding the optimal duration of biologic therapy and the safety of treatment discontinuation in patients who achieve sustained remission.

This prospective study aims to evaluate the outcomes of planned biologic treatment withdrawal in patients with Takayasu arteritis who have been in long-standing clinical and radiologic remission and have received biologic therapy for at least three years. Eligible patients will undergo a predefined 3-month dose tapering protocol. Patients who remain relapse-free during this period will discontinue biologic therapy and will be followed for 12 months.

The primary objective of the study is to determine the proportion of patients who maintain remission after biologic treatment withdrawal. Secondary objectives include evaluating the rate and timing of disease relapse during the tapering phase and the post-withdrawal follow-up period.

Takayasu arteritis (TAK) is a chronic granulomatous large-vessel vasculitis that primarily affects the aorta and its major branches. Despite advances in treatment, many patients require long-term immunosuppressive therapy to maintain disease control. Biologic agents, particularly tumor necrosis factor inhibitors and interleukin-6 receptor inhibitors such as tocilizumab, have demonstrated efficacy in refractory or relapsing disease. However, there is limited evidence regarding the optimal duration of biologic therapy and the safety of treatment discontinuation in patients who achieve sustained remission.

This prospective interventional study is designed to evaluate the outcomes of planned biologic treatment withdrawal in patients with Takayasu arteritis who have achieved long-standing clinical and radiologic remission and have received biologic therapy for at least three years. Eligible patients will undergo a predefined dose tapering protocol over a 3-month period. Patients who do not experience relapse during this phase will discontinue biologic therapy completely at the end of the tapering period.

Following treatment discontinuation, patients will be followed for 12 months. Clinical and laboratory evaluations will be performed at 1 month after discontinuation and every 3 months thereafter. Imaging studies will be performed as clinically indicated.

The primary outcome of the study is the proportion of patients maintaining remission at 12 months after biologic treatment withdrawal. Secondary outcomes include the rate and timing of major and minor relapses during the tapering phase and the post-withdrawal follow-up period. Additional analyses will explore potential predictors of relapse and differences according to biologic agent type and concomitant therapies.

Inclusion Criteria:

• Diagnosis of Takayasu arteritis according to the 2022 American College of Rheumatology/EULAR classification criteria
• Treatment with biologic therapy (TNF inhibitors or tocilizumab) for at least 3 years
• Sustained clinical, laboratory, and radiologic remission
• No change in treatment during the previous 12 months
• No glucocorticoid use within the previous 6 months
• Ability and willingness to provide written informed consent

Exclusion Criteria:

• Presence of other active inflammatory diseases requiring biologic therapy (e.g., inflammatory bowel disease, ankylosing spondylitis)
• Inability to attend scheduled follow-up visits after treatment tapering and discontinuation
• Pregnancy or planning pregnancy during the study period

De-identified individual participant data will be available upon reasonable request and subject to approval by the principal investigator and the ethics committee, in accordance with institutional and ethical regulations.

Data will be available after publication of the study results and will be accessible for 5 years.

Data will be available upon reasonable request to the principal investigator. Requests will be evaluated based on scientific merit, and data will be shared in anonymized form in accordance with institutional and ethical guidelines.