OUP accepted manuscript

Small molecules in idiopathic inflammatory myopathies: a systematic review and a multicenter case series about Janus kinase inhibitors and apremilast

OBJECTIVE

Idiopathic inflammatory myopathies (IIM) are rare autoimmune diseases that primarily affect striated muscles; skin, joints, and lungs may be involved with different degrees of severity. Traditional treatment relies on high-dose glucocorticoids and conventional synthetic disease-modifying antirheumatic drugs.

METHODS

A growing amount of evidence is demonstrating the potential role of novel treatments in the management of IIM. We report our experience with Janus kinase inhibitors (JAKi) in these conditions and review the current evidence for the use of small molecules in real-life clinical practice.

RESULTS

A total of 41 papers were retrieved from PubMed, 37 papers concerning IIM and JAKi, and 4 papers concerning IIM and apremilast.

CONCLUSIONS

An overall good efficacy was evidenced in IIM-associated skin lesions, including rash, ulcers, and calcinosis. If present, muscle and joint involvement demonstrated a good response to therapy, while it was not possible to draw any conclusion about dysphagia. No life-threatening adverse events were reported.

MDA5-positive dermatomyositis without muscle weakness and rash: a case report and literature review

Melanoma differentiation-associated gene 5 (MDA5)-positive dermatomyositis (DM) is a rare systemic autoimmune disease associated with a high rate of mortality attributable to rapidly progressive interstitial lung disease. MDA5-positive DM is often complicated by a typical rash and muscle weakness. Herein, we describe a 50-year-old woman who presented with worsening pulmonary symptoms with an absence of typical clinical characteristics. We also review the treatments and prognosis made in similar cases, highlighting that closer attention should be paid to patients presenting with atypical DM, particularly when clinical manifestations such as rash and muscle weakness are not apparent.

Update on dermatomyositis

PURPOSE OF REVIEW

This review summarizes and comments on current knowledge in dermatomyositis.

RECENT FINDINGS

The 2018 European Neuromuscular Centre classification of dermatomyositis has been challenging by the discovery of clinicopathological features associated with dermatomyositis-specific antibody (DMSA) that were not incorporated in the original criteria. These features include but may not be limited to the presence of perifascicular necrosis in anti-Mi-2 dermatomyositis; presence of diffuse nonperifascicular sarcoplasmic myxovirus resistance protein A expression in anti-MDA5 dermatomyositis; and dermatomyositis sine dermatitis in anti-NXP-2 dermatomyositis. Variations and subclassifications within the same DMSA subtypes are observed: anti-MDA5 dermatomyositis is clinically subcategorized into good, intermediate, and poor prognostic subgroups; concurrent anti-CCAR1 and anti-TIF1-γ positivity identify anti-TIF1-γ-positive patient with a lower risk for cancer-associated myositis. Owing to distinct IFN1-signaling pathway activation in dermatomyositis, JAK-STAT inhibitor - the pathway-targeted therapy, have been studied with promising results in refractory dermatomyositis and some new-onset dermatomyositis. In addition, the potential serum biomarkers for IFN1 pathway activation are being investigated for their performance in monitoring the disease activity and the efficacy of the treatment.

SUMMARY

DMSA, evidence of prominent IFN1 pathway activation, and risk/severity-associated biomarkers would likely play major roles in future dermatomyositis classification, disease monitoring, and treatment decision.