Systemic sclerosis: from pathogenesis to targeted therapy

Abstract

Systemic sclerosis (scleroderma) leads to morbidity and mortality through a combination of inflammation, fibrosis and vascular damage leading to internal organ complications affecting the heart, lung, kidneys and bowel. More than half of those diagnosed ultimately die from the disease. Current treatments focus on broad spectrum immunosuppression or organ-based therapy for complication such as lung fibrosis, pulmonary or systemic hypertension. Targeting peptide mediators such as endothelin-1 have already led to licensed effective therapies for SSc vasculopathy. Outcomes are improving but as well as providing a major clinical challenge there are great opportunities for research translation that can be expected to improve understanding of the pathogenesis of SSc and also develop better and more targeted therapy. Key pathways and mediators can be identified within the skin and blood vessels and these are now being examined in early stage clinical trials. Promising results are emerging from targeting cytokine signalling, including IL-6, and from other immune-inflammatory therapies including lipid mediators such as LPA1. Other approaches to modulate TGFbeta and other profibrotic pathways also have potential although safety and toxicity remain to be determined. Since many profibrotic pathways have important physiological roles the assessment of safety and toxicity will be paramount. Nevertheless, advances in understanding the interplay between different pathological processes and progress in clinical trial design and patients stratification mean that targeted therapies are emerging and likely to be further developed and refined to have application in other important clinical contexts such as lung fibrosis.