While understanding progresses regarding dermatomyositis, inclusion body myositis remains poorly understood. Dr. Greenberg suspects that inclusion body myositis may be an RNA sequestration disease. He noted that earlier theories that had dominated thinking in the field—such as beta-amyloid and tau accumulation—are now viewed as unfounded.
Tempered Enthusiasm for New Treatments
Because of their heterogeneity and chronicity, idiopathic inflammatory myopathies pose challenges for physicians, said Chester V. Oddis, MD, professor of medicine in the division of rheumatology and clinical immunology at the University of Pittsburgh, who presented an overview of current treatment and future options. “We have to take care of these patients for quite some time, so we’ve got to have some things up our sleeves.”
Recommended Reading
- Wortmann R, DiMauro S. Differentiating idiopathic inflammatory myopathies from metabolic myopathies. Rheum Dis N Amer. 2002;28:759-778.
- Vladutiu, GD. Laboratory diagnosis of metabolic myopathies. Muscle Nerve. 2002;25:649-662.
- Kagen I. Evaluation of the patient. In The Inflammatory Myopathies, Kagen IJ ed. M/Humana Press, 2009; p.1-14.
- Greenberg SA., Sanoudou D, Haslet JN, et al. Molecular profiles of inflammatory myopathies. Neurology. 2002;59:1170-1182.
- Amato AA, Barohn RJ. Inclusion body myositis: old and new concepts. J Neurol Neurosurg Psychiatry. 2009;80:1186-1193.
Pharmacologically speaking, there are more treatment options for myositis, including steroids, immunosuppressive agents, combination regimens, immunomodulatory agents, and biologics. However, most of the data on the use of these therapies is empiric and anecdotal, he cautioned. At his institution, patients with active and aggressive myositis receive divided dose steroids, in 20-mg tolerable daily intake fashion. When their serum CK levels normalize, patients’ doses are consolidated to a single morning dose. The steroid dose is then tapered by 25% every three to four weeks until the 5–10-mg threshold is reached. “In an ideal setting—that is, in a patient who responds well to steroids—we oftentimes continue this [maintenance] dose for a year or so,” Dr. Oddis said.
Methotrexate and azathioprine are generally used after steroids, sometimes concomitantly to manage extramuscular manifestations. There is limited evidence that combination therapy is effective in treatment-resistant myositis, he said. Small studies have shown good results for mycophenolate mofetil to treat the cutaneous features and associated interstitial lung disease in DM.
Dr. Oddis discussed myositis patients with the Jo-1 anti-synthetase autoantibody. Patients with this clinical phenotype often present in the acute stages of systemic disease, with pulmonary symptoms, fever, inflammatory arthritis, and Raynaud’s phenomenon. The clinical picture can look like rheumatoid arthritis, and these patients are particularly challenging to treat, he said. They may also require concomitant antiinflammatory and immunosuppressant therapy, and his group has had some success with tacrolimus in these patients. Other potential targets of therapy, such as tumor necrosis factor–α, offer some promise. Dr. Oddis is principal investigator on the RIM (rituximab in myositis) Study, the first international, collaborative, multicenter clinical trial in 200 patients with IIM.
