As far as myositis treatments go, there have been few randomized controlled trials, so case series are the main guide.
Dr. Lundberg said the targeting of B cells has shown some promise. In the RIM trial (Rituximab in the Treatment of Refractory Adult and Juvenile Dermatomyositis and Adult Polymyositis), a multicenter trial involving 200 patients, the time to improvement endpoint wasn’t met, but overall, 83% of the patients met the definition of improvement.2 Twenty-six percent of patients suffered a serious adverse event, mainly infections. There was also a glucocorticoid-sparing effect between baseline and the study’s conclusion.
“What we can conclude, I think, from this study is that B cells may be important in the pathogenesis of myositis and targeting B cells may be effective in treatment-resistant [polymyositis or dermatomyositis] cases,” Dr. Lundberg said.
Antitumor necrosis factor therapy has led to mixed results, and an interleukin-1 blockade has shown some promise, she said. “We need to identify subgroups with shared disease mechanisms” to make potential therapies more beneficial, she said.
Therapy with a more clear benefit is physical exercise, she said.
Patients with chronic polymyositis or chronic dermatomyositis who underwent seven weeks of resistance exercise showed improved strength and that genes involved in inflammation were downregulated.3
“What we know about physical exercise in myositis today is that it’s safe, it can really improve muscle performance and strength, can improve your oxygen uptake, and it might reduce inflammation.”
Thomas Collins is a freelance medical journalist based in Florida.
References
- Labrador-Horrillo M, Martínez MA, Selva-O’Callaghan A, et al. Anti-TIF1γ antibodies (anti-p155) in adult patients with dermatomyositis: Comparison of different diagnostic assays. Arthritis Rheum. 2012;71:993-996.
- Oddis CV, Reed AM, Aggarwal R, et al. Rituximab in the treatment of refractory adult and juvenile dermatomyositis and adult polymyositis: A randomized placebo-phase trial. Arthritis Rheum. 2013;65:314-324.
- Dastmalchi M, Alexanderson H, Loell I, et al. Effect of physical training on the proportion of slow-twitch type I muscle fibers, a novel nonimmune-mediated mechanism for muscle impairment in polymyositis or dermatomyositis. Arthritis Rheum. 2007;15;57:1303-1310.
