1.10　Treatments

Both type 1 and type 2 AIP patients respond well to corticosteroids.In an international multicenter study，681/684（99.6%）patients with type 1 AIP and 48/52（92.3%）patients with type 2 AIP achieved clinical remission by the initial treatment with corticosteroid（Hart et al.2013a）.In a multicenter study from Japan，the remission rate was higher in corticosteroid-treated AIP patients than in those with no treatment（98%vs.74%，P＜0.001）（Kamisawa et al.2009）.Based on these observational studies，corticosteroid has been established as the standard therapy for the treatment of AIP patients（Hart et al.2013a；Kamisawa et al.2009；Pannala and Chari 2009；Kamisawa et al.2014），and a rapid response to the corticosteroid treatment is included in the ICDC（Shimosegawa et al.2011）.Known risk factors for disease relapse include proximal biliary involvement（Ghazale et al.2008；Hart et al.2013a）and presentation with diffuse pancreatic enlargement（Sah et al.2010；Kubota et al.2011）.

The requirement of maintenance therapy has been controversial.Maintenance therapy is not common in the United States and Europe，due to the concern of serious corticosteroid-related complications caused by increased cumulative amounts of corticosteroid（Ghazale et al.2008；Pannala and Chari 2009）.One standard protocol is the administration of oral prednisolone（PSL）for 4 weeks followed by tapering by 5 mg each week until being discontinued after 11 weeks（Ghazale et al.2008）.In addition，nearly half of the patients do not relapse even without maintenance therapy，and relapsed cases respond well to the re-administration of corticosteroid（Ghazale et al.2008）.However，many patients who achieved remission relapsed soon after the cessation of corticosteroid treatment.In a Pittsburg study，9 out of 15（60%）patients who achieved complete remission developed relapses within 8-12 weeks after the corticosteroid cessation（Raina et al.2009）.In Japan，long-term maintenance therapy with low-dose corticosteroid is preferred and recommended in the Japanese guidelines（Kamisawa et al.2014）.In a multicenter study from Japan，10/38（26%）cases relapsed during maintenance treatment with PSL at more than 5 mg/day，and this was significantly lower than the relapse rate of 14/26（54%）patients who discontinued the therapy（Kamisawa et al.2010）.Very recently，Masamune et al.（2016）reported a randomized controlled trial of long-term maintenance corticosteroid therapy in Japan.They showed that long-term maintenance corticosteroid therapy for 3 years（maintenance therapy group）significantly decreased relapses in AIP patients compared with those who discontinued the therapy at 26 weeks（cessation group）.Seven out of 30（23.3%）patients in the maintenance therapy group developed relapses，whereas 11 out of 19（57.9%）patients in the cessation group relapsed within 3 years.The relapse rate over 3 years was significantly higher in the cessation group than that in the maintenance therapy group（P=0.011）.No serious steroid-associated complications such as serious infection requiring discontinuation of PSL administration were observed.Although this study had several limitations including its small sample size，the results suggested that long-term low-dose maintenance corticosteroid therapy would be an option to decrease relapses.(https://www.daowen.com)

For patients who are either intolerant of corticosteroids or have multiple relapses，there are other treatment options including corticosteroidsparing immunomodulators and B-cell depletion therapy using rituximab to avoid increased cumulative amounts of corticosteroid（Hart et al.2013b）.