LONDON – Tumor necrosis factor–inhibitor treatment improved refractory skin disease in juvenile dermatomyositis patients in the largest observational study of its kind from the United Kingdom and Ireland Juvenile Dermatomyositis Research Group.
Muscle disease in the juvenile dermatomyositis (JDM) patients largely had already improved with conventional therapies prior to treatment with anti–tumor necrosis factor (TNF)-alpha agents, but it did improve further with anti-TNFs.
The effect of TNF inhibitors was most notable for those with skin calcinosis, lead author Dr. Raquel Campanilho-Marques reported at the European Congress of Rheumatology on behalf of her colleagues in the Juvenile Dermatomyositis Research Group.
Some evidence suggests that TNF-alpha might be involved in the pathogenesis of idiopathic inflammatory myopathies, particularly in more prolonged courses of JDM.
But there is limited prior evidence for the efficacy of TNF inhibitors in JDM patients, where small observational studies and case series have shown improved core-set measures of disease activity in patients treated with anti-TNF agents, noted Dr. Campanilho-Marques, a pediatric rheumatologist in the infection, inflammation and rheumatology section at the University College London Institute of Child Health and the Great Ormond Street Hospital for Children NHS Trust in London.
The 67 patients in the study involved those who were enrolled in the JDM Cohort and Biomarker Study, met Bohan and Peter criteria for JDM, and were on anti-TNF therapy at the time of analysis because of nonresponse to conventional therapy, active skin disease, calcinosis, or muscle weakness. They had at least 3 months of anti-TNF therapy and received either infliximab 6 mg/kg every 4 weeks (after a standard initial induction regimen) or adalimumab (Humira) 24 mg/m2 every other week.
A majority of the patients in the study were female (n = 41) and white (n = 54), with a mean age at disease onset of about 5 years. At the time of first use of anti-TNF agents, the patients had a mean age of about 10 years and a mean disease duration of 3.2 years. Treatment with TNF inhibitors lasted for a mean of about 2.5 years.
Of the 67 patients, data were not analyzed for 4 patients; there was insufficient information for 1 patient, while 3 patients had allergic reactions to their anti-TNF therapy on the first or second infusion. The remaining 63 patients included 43 who received infliximab, 4 on adalimumab, and 16 who used both.
Prior to anti-TNF treatment, 52 of 53 patients (98%) were taking methotrexate, azathioprine, hydroxychloroquine, or a combination of those. That declined to 45 of 56 (80%) at the start of anti-TNF therapy and then increased to 44 of 49 (89%) after 12 months of using an anti-TNF agent.
The use of cyclophosphamide declined markedly, from 26 of 65 patients (40%) to 3 of 65 (5%) at the start of TNF inhibition, and then to none after 12 months of anti-TNF therapy. Immunoglobulin therapy also declined, from use in 10%-12% of patients before and at the start of anti-TNF treatment to just 1 of 41 patients (2%) after 12 months of TNF inhibitor therapy.
The median modified Disease Activity Score for skin involvement significantly improved over the course of 12 months of treatment with infliximab, decreasing from 4 to 1. That was also the case for Physician Global Assessment score, as well as muscle outcome measurements on the Childhood Myositis Assessment Scale (CMAS) and the 8-item Manual Muscle Testing (MMT8).
For the 31 patients in the study who had calcinosis, lesions improved (reduced in number and/or size) in 17 patients, including 8 with complete resolution of their lesions. In the other 14 patients, lesions remained stable in 3 (fewer than three lesions) and were widespread or did not improve in 4; the other 7 patients had insufficient data to determine outcomes.
Most patients with muscle involvement already had improved with steroids prior to using anti-TNF drugs. Thus, the improvement in CMAS and MMT8 scores on anti-TNF treatment was not very large, going from about 45 to 53 and from about 74 to 79, respectively.
The investigators did not examine treatment response in relation to muscle-specific antibodies, but Dr. Campanilho-Marques said that it is something they would like to do in the future.
The main indication for anti-TNF agents was active skin disease that had not responded to conventional treatment, noted Dr. Campanilho-Marques, who is also with the departments of rheumatology at the Santa Maria Hospital and the Instituto Português de Reumatologia, both in Lisbon.
For 16 patients who switched from infliximab to adalimumab, the changes in outcome measures were not statistically significant. The switches occurred at a median of 2.35 months after starting infliximab; 10 patients switched because of inefficacy, 4 because of adverse events, and 2 because of patient preference.