Azathioprine and Mycophenolate Mofetil May Benefit Myositis-Related ILD

interstitial pulmonary fibrosis
In patients with myositis-related interstitial lung disease, azathioprine and mycophenolate mofetil treatment offers clinical improvements and a reduction in prednisone dose.

In patients with myositis-related interstitial lung disease (ILD), treatment with azathioprine is associated with improved percent predicted forced vital capacity (FVC%), percent predicted diffusion capacity (DLCO%), and prednisone dose, while treatment with mycophenolate mofetil is associated with improved FVC% and prednisone dose, according to study results published in CHEST.1

Myositis-related ILD can be progressive and potentially fatal, if left untreated, with a 5-year mortality ranging from 9% to 40%.2-4 Azathioprine and mycophenolate mofetil are typical first-line steroid-sparing immunosuppressive agents, but most of the efficacy and safety data on these agents are in patients with connective tissue disease-associated ILD.

Therefore, researchers conducted a retrospective study in patients with myositis-related ILD seen at the Johns Hopkins Myositis Center and the John Hopkins ILD Clinic in Baltimore, Maryland, and treated with either azathioprine (n=66) or mycophenolate mofetil (n=44) and no other steroid-sparing agents.1

At the beginning of the study, the mean FVC% and DLCO% were significantly lower in the azathioprine group than in the mycophenolate mofetil group. While FVC% improved and participants’ prednisone dose was reduced during the course of 2 to 5 years in the mycophenolate mofetil group, only DLCO%, improved in the azathioprine group. In addition, adverse events were more frequent in the azathioprine group than in the mycophenolate mofetil group (33.3% vs 13.6%: P =.04).

“In conclusion, our observational study showed that the use of [azathioprine] was associated with improvement of FVC%, DLCO% and reduction of prednisone dose. The use of [mycophenolate mofetil] was associated with improvement of FVC% and reduction of prednisone dose, and stabilization of DLCO% in patients with myositis-related ILD over 2 [to] 5 years,” the researchers wrote.1

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Disclosures: Dr Christopher-Stine reports financial relationships with Corbus Pharmaceuticals, Pfizer, Kezar, CSL Behring, and Novartis. Dr Christopher-Stine has also served on advisory boards for OptionCare, Mallinckrodt, AstraZeneca, and Kezar, and has received royalties from Inova Diagnostics.


  1. Huapaya JA, Silhan L, Pinal-Fernandez I, et al. Long-term treatment with azathioprine and mycophenolate mofetil for myositis-related interstitial lung disease [published online June 22, 2019]. CHEST. doi:10.1016/j.chest.2019.05.023
  2. Johnson C, Connors GR, Oaks J, et al. Clinical and pathologic differences in interstitial lung disease based on antisynthetase antibody type. Respir Med. 2014;108(10):1542-1548.
  3. Arsura EL, Greenberg AS. Adverse impact of interstitial pulmonary fibrosis on prognosis in polymyositis and dermatomyositis. Semin Arthritis Rheum. 1988;18(1):29-37.4.
  4. Marie I, Hatron PY, Dominique S, Cherin P, Mouthon L, Menard JF. Short-term and long-term outcomes of interstitial lung disease in polymyositis and dermatomyositis: a series of 107 patients. Arthritis Rheum. 2011;63(11):3439-3447.