MAUI, HAWAII – Anti-Ro52 autoantibodies are the latest and most potent of the autoantibody predictors of interstitial lung disease (ILD) discovered in patients with juvenile dermatomyositis, Anne M. Stevens, MD, PhD, said at the 2020 Rheumatology Winter Clinical Symposium.
Bruce Jancin/MDedge News
Dr. Anne M. Stevens
In addition to detailing the autoantibody red flags for ILD in juvenile dermatomyositis (JDM), she called for “hypervigilance” in patients with systemic juvenile idiopathic arthritis (SJIA) who exhibit any of a series of risk factors for ILD.
“Most of the lung disease in kids with systemic JIA is asymptomatic until very late, but it can be reversible if we treat it. So it’s worth finding and monitoring and giving everyone PCP [pneumocystis pneumonia] prophylaxis, because they have a high incidence of PCP if they have any of those risk factors,” observed 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 12% of 25 patients with juvenile polymyositis and in 18% of 44 youths with an overlap of juvenile connective tissue disease and myositis. 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 antimelanoma differentiation–associated protein 5 (anti-MDA5) autoantibodies, and antiaminoacyl tRNA synthestase (anti-Jo-1) autoantibodies were present in 4%.
A total of 33 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-Jo-1. After controlling for the presence of these other myositis-specific autoantibodies, auto-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-Jo-1 positive.
Patients with anti-Ro52 autoantibodies had a worse prognosis, with more severe and chronic disease, Dr. Stevens noted.
Novel potential treatment for ILD in JDM: JAK inhibitors
Standard treatment of ILD in JDM in all cases includes high-dose pulsed corticosteroids, intravenous immunoglobulin (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.
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 did 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.
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.
Risk factors for ILD in SJIA
In the past half-dozen years or so, pediatric rheumatologists have become increasingly aware of and concerned about a new development in SJIA: the occurrence of comorbid ILD. This is a poor-prognosis disease: In a cohort from the United Kingdom, 5-year mortality from the time of diagnosis was 41%, fully 40-fold higher than in patients with SJIA only.
Patient cohorts with SJIA and ILD have unusual clinical and laboratory features that aren’t part of the typical picture in SJIA. These include acute clubbing, lymphopenia, a fixed pruritic rash, unexplained abdominal pain, peripheral eosinophilia, facial swelling, and an increased ferritin level, a hallmark of acute macrophage activation syndrome. Onset of SJIA before 2 years of age is another red flag associated with increased risk for ILD. So is trisomy 21, which is up to 50 times more prevalent in patients with SJIA and ILD than in the general population or in patients with SJIA only. Another clue is an adverse reaction to tocilizumab (Actemra).
Any of these findings warrant hypervigilance: “Be on high alert and monitor these patients for ILD much more closely,” Dr. Stevens advised.
This means ordering a CT scan, prescribing PCP prophylaxis, and regularly measuring pulmonary function, admittedly a challenge in children under 7 years old. In these younger kids, practical solutions include measuring their oxygen saturation before and after running around the room to see if it drops. A 6-minute walk test and sleep oximetry are other options.
The explanation for the abrupt arrival of ILD as part of the picture in SJIA during the past decade remains unclear. The timing coincides with a major advance in the treatment of SJIA: the arrival of biologic agents blocking interleukin-1 and -6. Could this be a serious treatment side effect?
“It’s all association so far, and we’re not really sure why we’re seeing this association. Is it because we’re using a lot [fewer] corticosteroids now, and maybe those were preventing lung disease in the past?” Dr. Stevens speculated.
At this point, she and her fellow pediatric rheumatologists are awaiting further evidence before discussing a curb in their use of IL-1 or -6 inhibitors in patients with SJIA.
“These drugs have turned around the lives of kids with SJIA. They used to suffer through all our ineffective treatments for years, with terrible joint destruction and a pretty high mortality rate. These are great drugs for this disease, and we certainly don’t want to limit them,” she said.
Dr. Stevens reported research collaborations with Kineta and Seattle Genetics in addition to her employment at Janssen Pharmaceuticals.