Table 3.

Case studies or case series of JAK-inhibitors in juvenile dermatomyositis

Case study	JAK-inhibitors	Patient	Disease course and prior treatment	Outcome
Aeschilimann et al. 2018 [121]	ruxolitinib	13 year old; JDM (anti-NXP2)	- Un-controlled disease with admission to ICU - Complexity of severe symptoms over 18 months -Prednisolone dependant, refractory to treatment including; methotrexate, IVIG, plasma exchange, MMF and rituximab -Increased IFN scores and STAT1 phosphorylation of T-cells and monocytes	After 52 weeks (12 months) of treatment: -Improvement of disease activity scores - decreased STAT1 phosphorylation in T-cells
Papadopoulou et al. 2019 [122]	baricitinib	11 year old; JDM (anti-TIF1-γ, anti-Ro52)	- 7 year history of JDM (with calcinosis) - steroid dependant; refractory to sequential treatment with azathioprine, mycophenolate mofetil, infliximab, adalimumab, rituximab, tacrolimus and cyclosporine, intravenous immunoglobulin (IVIG) - negative for class 4 and 5 variants of monogenic interferonopathies	After 26 weeks (6 months) of treatment: - clear improvement of disease - IFN biomarkers decreased - decreased level of CEC
Sabbagh et al. 2019 [123]	tofacitinib	2 anti-MDA5 JDM patients 12y/o male 15y/o female	Elevated 28-gene IFN score Un-controlled disease: Patient 1 – continuous flares after treatment with pulsed methylprednisolone, IVIg, methotrexate, MMF, rituximab Patient 2 – continuous flares after treatment with pulsed methylprednisolone, IVIg, MMF, abatacept, cyclophosphamide, rituximab and sildenafil	After 26 week (6 months) of treatment: - decrease in disease activity score - Decrease of IFN score and STAT1 phosphorylation of T-cells and monocytes
Yu et al. 2020 [124]	tofacitinib	n = 3 JDM 11y/o fem (ANA 1:320, anti-MDA5) 10y/o female (ANA 1:80, anti-Mi-2, anti-Ro-52 10y/o male (Negative)	Refractory JDM: patients failed ≥2 steroid sparing agents or high-dose steroids.	After 26 week (6 months): - Significant improvement of clinical scores; CMAS, MMT8, PGA, DAS and CHAQ
Le Voyer et al. 2021 [125]	baricitnib ruxolitinib	n = 3 JDM 2/3 female mean 8.7 years [25–30] NXP2 = 1 TIF1-y = 1 MDA5 = 1 No MSA = 0 n = 7 JDM 5/7 female mean 9.1 years [1, 2, 25–33] NXP2 = 3 TIF1-y = 2 MDA5 = 1 No MSA = 1	9 refractory disease and 1 new-onset Refractory muscle involvement (n = 8) Ulcerative skin disease (n = 2)	After 26 weeks (6 months): →Improvement in clinical scores →Clinically inactive disease →Decrease in seral IFN-α
Ding et al. 2021 [126]	tofacitinib 7/25 (28%) ruxolitinib 18/25 (72%)	n = 25 JDM 11/25 (44%) female Mean age of onset 4.6 ± 3.3 years Mean age to start JAK inhibitors 7.2 ± 4 years	All refractory 8/25 (32%) ineffective treatment 17/25 (68%) glucocorticoid dependant	25 patients followed up median of 34 weeks (7 months) (range – 3-21 months) →24/25 (96%) had rash improvement, 16/24 (66.7%) complete resolution →7/25 (28%) improved CMAS
Kim et al. 2021 [127]	baricitinib	4 JDM (5.8–20.7 years old)	→Chronically active disease →Failed 3–6 immunomodulatory medications	After 24 weeks of treatment: →Disease improvement assessed by clinical score →Down regulation of IRG →Decrease in serum IP-10