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Safety and Effectiveness of Canakinumab in Patients with Systemic Juvenile Idiopathic Arthritis in Japan: A Post-Marketing Surveillance Study

Year: 2026

Type: article

Abstract: Canakinumab was approved in Japan for the treatment of patients with systemic juvenile idiopathic arthritis (sJIA) in 2018, following an open-label, single-arm phase III study performed in 19 Japanese patients with sJIA. Given this limited sample size, Japanese regulatory authorities required an all-case post-marketing surveillance study as part of the approval conditions, aiming to assess the long-term safety and effectiveness of canakinumab in Japanese patients with sJIA in clinical practice and characterise the clinical course of any cases of macrophage activation syndrome (MAS). This was a multicentre, central registration, all-case, uncontrolled, open-label, special drug use investigation, including all patients who received canakinumab for the treatment of sJIA between 2 July 2018 and 20 December 2024. Patients were treated according to the investigators’ routine clinical practice and observed for up to 104 weeks. The safety analysis population included 125 patients with a median duration of treatment (including interruptions) of 710.0 (range 1–729) days and median total number of doses of 25.0 (range 1–29). Adverse events (AEs) occurred in 91 out of 125 patients (72.8%), with the most common being relapse, worsening or exacerbation of Still’s disease (24 patients, 19.2%), followed by upper respiratory tract inflammation (18 patients, 14.4%). Serious related AEs occurred in 22 patients (17.6%), with the most common being haemophagocytic lymphohistiocytosis (HLH; 5 patients, 4.0%). A total of ten MAS-related AEs were reported; all were cases of HLH and were considered serious, and all were resolved or were resolving at the time of reporting. Effectiveness outcomes, including glucocorticoid tapering, disease activity reduction and inflammatory marker normalisation, were durable through 2 years of treatment. Canakinumab showed a favourable long-term safety profile and sustained effectiveness in Japanese patients with sJIA inadequately controlled by existing therapies. No new safety concerns emerged, and the safety profile was comparable to that observed in the earlier phase III study. Systemic juvenile idiopathic arthritis (sJIA) is a rare and serious type of childhood arthritis that can cause fever, rash and inflammation throughout the body. Canakinumab is a medicine that blocks interleukin-1β, a protein involved in inflammation and an important driver of sJIA. Canakinumab was approved in Japan in 2018 for the treatment of sJIA. To gather additional safety information after approval, all patients in Japan who received canakinumab for sJIA were registered in a post-marketing surveillance study. In the study reported here, we collected data from patients for up to 2 years during routine clinical care with canakinumab. A total of 125 patients were included in the safety analysis. About three-quarters (73%) of these patients experienced at least one adverse event, with the most common being a relapse or worsening of Still’s disease or upper respiratory tract inflammation. Serious adverse events considered to be related to treatment occurred in 18% of patients; the most frequent of these was a form of a life-threatening complication of sJIA called macrophage activation syndrome. However, all cases of macrophage activation syndrome had resolved or were improving by the time that the study results were reported. Overall, canakinumab showed a favourable long-term safety profile and maintained its effectiveness over 2 years in Japanese patients with sJIA. No new safety concerns were identified compared with an earlier clinical study.

Source: Rheumatology and Therapy

DOI: 10.1007/s40744-025-00822-1

Authors: Fumio Akita, Noriko Seko, Tomohiro Yoneda

Institution: Novartis (Japan)

Language: English

Topic: Autoimmune and Inflammatory Disorders Research

Subfield: Hematology

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $7,400