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Background: The GiACTA trial 1 demonstrated the efficacy of tocilizumab (TCZ) in treating giant cell arteritis (GCA). However, since the trial did not include Japanese patients, the data on the effectiveness of TCZ, particularly beyond one year, is still lacking in the Japanese population. Furthermore, the treatment strategy and clinical courses following relapses in patients with GCA treated with TCZ remain unclear. Objectives: The purpose of this study is to examine a relapse rate of GCA treated with TCZ in a real-world setting and to reveal clinical courses after the relapses. Methods: This multi-center retrospective study targeted GCA patients who started TCZ at seven Japanese hospitals from January 2008 to July 2021. Detailed clinical information was collected up to 2 years after TCZ initiation. We examined relapse-free survival after initiating TCZ. Cases with relapse were described in detail; we summarized the symptoms at the time of relapse, treatment details, treatment modifications following relapses, and subsequent clinical courses. Results: Sixty-two patients diagnosed with GCA and treated with TCZ were identified. The median age was 74 years, and 40 (65%) were female. Ten cases experienced a relapse (Figure 1). Two of them relapsed while using a full dose of TCZ, and the remaining eight relapsed after TCZ discontinuation or spacing (Table 1). The median daily prednisone (PSL) dose at relapse was 5.5 mg (range, 5-6 mg) in patients on TCZ, 0 mg (range, 0-4 mg) in patients after spacing the TCZ interval, and 5 mg (range, 3-7 mg) in those who discontinued TCZ for any reasons. Signs and symptoms at relapse included exacerbation of polymyalgia rheumatica(PMR) in 60% (6/10), ocular symptoms in 10% (1/10), head pain (scalp pain, temporal pain) in 10% (1/10), cough in 10% (1/10), and elevated C-reactive protein in 10% (1/10).Treatment modifications after the relapses were as follows: three patients increased PSL with adding or increasing MTX; three shortened their TCZ intervals; one resumed the interrupted TCZ with glucocorticoid injections to both shoulders; and the remaining three cases only increased PSL. The one patient who increased PSL alone then restarted TCZ with tapering PSL. PSL was increased to 30mg in a patient experiencing amaurosis fugax, but other cases required only a slight increase in daily PSL doses up to 10 mg. Symptoms or signs of GCA improved shortly after treatment modification in most cases. Only two cases remained symptomatic of mild PMR at 30 days, and these PMR symptoms subsequently resolved 60 days after the relapses. Conclusion: This retrospective study found a low relapse rate after initiation of TCZ in Japanese patients with GCA. Even in cases of relapse, the symptoms were relatively mild. In the patients with relapsed GCA, shortening the TCZ intervals and increasing the dose of MTX resulted in resolution of symptoms despite only a small increase in glucocorticoid dosage. REFERENCES: 1 Stone JH, et al. Trial of Tocilizumab in Giant-Cell Arteritis. N Engl J Med. 2017 Jul 27;377(4):317-328. Table 1. Acknowledgements: NIL. Disclosure of Interests: Fumika Nagase: None declared, Sho Fukui: None declared, Toshihiro Yamaguchi: None declared, Nobuhiro Oda: None declared, Takanori Ito: None declared, Mitsuru Watanabe: None declared, Yoichiro Haji: None declared, Yasuhiro Suyama: None declared, Ryo Rokutanda: None declared, Atsushi Nomura: None declared, Eishi Uechi: None declared, Masei Suda: None declared, Naoho Takizawa: None declared, Hiromichi Tamaki ABBVIE, Ayumi pharma, Astellas, Astrazeneca, Asahi Kasei pharma, Eli Lily, Eisai, Ono Pharmaceutical, Otsuka pharma, Dai-Ichi Sankyo, Chugai, Tanabe-Mitsubishi, GSK, Pfizer, Chugai.
Nagase et al. (Sat,) studied this question.