Background/Purpose: Takayasu arteritis (TAK) is a type of large-vessel vasculitis that predominantly affects young females. The relapse is frequent, accounting for 60% of cases, and molecular targeted drugs including tocilizumab (TCZ) and tumor necrosis factor inhibitor (TNFi) are used. Although the steroid-sparing effect of molecular targeted drugs has been reported in short period, information about the long-term efficacy and retention rate is scarce. The aim of this study is to investigate the long-term efficacy and retention rate of molecular targeted drugs in TAK.

Methods: 117 patients with TAK who satisfied the JCS or ACR classification criteria and visited Tohoku University Hospital during 2018 to 2022 were enrolled to this study. The use of molecular targeted drugs, clinical background, long-term efficacy and retention rate of the drugs were retrospectively evaluated.

Results: 45 of 117 patients (38.5 %) received molecular targeted drugs, and all were applied for the relapse of TAK. The clinical characteristics of patients required molecular targeted drugs included young age at onset and the presence of extra-arterial comorbidities. Eight and four patients required more than two and three molecular targeted drugs, respectively. The numbers of molecular targeted drugs used were as follows, TCZ, 35; TNFi, 12; JAK inhibitors, 2; abatacept, 1; rituximab, 1. During 45 months of median-follow up period after the initiation of molecular targeted drugs, the retention rate was as follows; TCZ, 77.1 %, TNFi, 91.6 %. TCZ was discontinued in following cases; infection, 3; major relapse, 2; exacerbation of extra-arterial manifestation, 2; infusion reaction, 1. In four patients who discontinued TCZ, TNFi was used as the 2^nd molecular targeted drug. Although the retention rate of TCZ was high, TCZ was not discontinued in following seven cases; worsening of vascular legion, 2; major relapse without vascular change, 2; minor relapse, 2; severe infection, 1. This was because there existed little evidences for the effectiveness of other molecular targeted drugs. The discontinuation of TCZ was frequent in patients receiving vascular surgery or complicating with extra-arterial comorbidities. Of note, severe colitis was observed in 8.8% of patients receiving TCZ, and infective endocarditis was also documented. The mean dose of prednisolone (PSL) was significantly reduced in patients receiving molecular targeted drugs, irrespective of drugs, as follows; before initiation, 10.1±3.9 mg/day; upon initiation 25.1±11.6㎎/day; the most recent, 5.6±3.7 mg/day. PSL was discontinued in seven cases treated with TCZ, and six cases remained relapse-free.

Conclusion: The retention rate of molecular targeted drugs was high, and molecular targeted drugs were useful for the maintenance of remission and reducing the dose of corticosteroid in relapsed cases. Nevertheless, there existed patients who were not able to change TCZ due to insufficient evidences of other molecular targeted drugs in TAK.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/long-term-efficacy-and-retention-rate-of-molecular-targeted-drugs-in-takayasu-arteritis/