MAUI, HAWAII – , Anne M. Stevens, MD, PhD, said at the 2020 Rheumatology Winter Clinical Symposium.
And in a recent potential treatment advance, Janus kinase inhibition shows promise as a novel therapy for ILD in patients with juvenile dermatomyositis (JDM), added Dr. Stevens, a pediatric rheumatologist at the University of Washington, Seattle, and senior director for the adaptive immunity research program at Janssen Pharmaceuticals.
Autoantibodies predict ILD in JDM
Dr. Stevens highlighted recent work by Sara Sabbagh, DO, of the National Institute of Arthritis and Musculoskeletal and Skin Diseases and coinvestigators in the Childhood Myositis Heterogeneity Collaborative Study Group. They reported the presence of anti-Ro52 autoantibodies in 14% of a cohort of 302 patients with JDM as well as in 3 (12%) of 25 patients with juvenile polymyositis and in 8 (18%) of 44 youths with juvenile connective tissue disease–myositis overlap. In addition, 13% of patients were positive for autoantibodies previously identified as being associated with ILD in these forms of juvenile myositis: namely, 9% of the cohort were positive for anti–melanoma differentiation–associated protein 5 (anti-MDA5) autoantibodies, and antiaminoacyl-tRNA synthetase (anti-Jo-1) autoantibodies were present in 4%.
Thirty-three of the 371 juvenile myositis patients had ILD based upon CT imaging, chest x-ray, dyspnea on exertion, and/or biopsy. Most patients with anti-Ro52 also had other autoantibodies associated with ILD. Indeed, 31% of patients with anti-MDA5 autoantibodies also had anti-Ro52, as did 64% of those with anti-Jo1. After controlling for the presence of these other myositis-specific autoantibodies, anti-Ro52 autoantibodies were independently associated with ILD, which was present in 36% of those with and just 4% of those without anti-Ro52 autoantibodies.
Importantly, if a patient with JDM or another form of juvenile myositis had both anti-Ro52 and another myositis-specific autoantibody, the risk for ILD rose dramatically, climbing to 70% in patients with anti-Ro52 and anti-MDA5 autoantibodies, and to 100% in those who were both anti-Ro52 and anti-Jo1 positive (Ann Rheum Dis. 2019 Jul;78[7]:988-95).
Patients with anti-Ro autoantibodies had a worse prognosis, with more severe and chronic disease, Dr. Stevens noted.
Potential treatment for ILD in JDM: JAK inhibitors
Standard treatment of ILD in JDM in all cases includes high-dose pulsed corticosteroids, IVIG, and either methotrexate or mycophenolate mofetil. Consideration should be given to adding cyclosporine, particularly when a macrophage activation–syndrome component is present. In addition, several exciting recent lines of evidence suggest a potential role for Janus kinase (JAK) inhibitors in the subset of JDM patients with anti-MDA5 autoantibody–positive disease, according to Dr. Stevens.
For one, Dr. Sabbagh and colleagues have reported impressive success with the use of the JAK 1/3 inhibitor tofacitinib (Xeljanz) in two patients with anti-MDA5 autoantibody–positive refractory JDM with ILD. Both patients experienced moderate clinical improvement in disease activity in their skin, muscles, and other target organs. But particularly striking was what the investigators termed the “remarkable” improvement in ILD, including near resolution of abnormal findings on high-resolution CT imaging and a more robust performance on pulmonary function testing.
Both of these hitherto treatment-refractory patients were able to wean or discontinue their immunosuppressive medications. The patients’ elevated blood interferon-response gene signature improved significantly in response to tofacitinib, and their problematic upregulation of STAT1 phosphorylation of CD4+ T cells and monocytes stimulated with interferon-gamma was tamed, dropping to levels typically seen in healthy individuals (Brain. 2019 Nov 1;142[11]:e59).
Also, French pediatric rheumatologists have identified key phenotypic and cytokine differences between 13 patients with JDM or juvenile overlap myositis who were anti-MDA5 autoantibody–positive at presentation and 51 others who were not. The anti-MDA5 autoantibody–positive group had a higher frequency of ILD, arthritis, skin ulcerations, and lupus features, but milder muscle involvement than the anti-MDA5 autoantibody–negative group. The anti-MDA5 autoantibody–positive patients demonstrated enhanced interferon-alpha signaling based upon their significantly higher serum interferon-alpha levels, compared with the anti-MDA5-negative group, and those levels decreased following treatment with improvement in symptoms (Rheumatology [Oxford]. 2019 Nov 22. doi: 10.1093/rheumatology/kez525. [Epub ahead of print]).
The French investigators proposed that interferon-alpha may constitute a novel therapeutic target in the subgroup of patients with severe, refractory juvenile myositis and anti-MDA5 autoantibodies – and, as it happens, it’s known that JAK inhibitors modulate the interferon pathway.
Dr. Stevens reported research collaborations with Kineta and Seattle Genetics in addition to her employment at Janssen Pharmaceuticals.