Biologics in Systemic Sclerosis: An Organ- and Manifestation-Specific Reappraisal of What Has Changed, What Has Not, and Why
Systemic sclerosis (SSc) is a heterogeneous autoimmune disease characterized by immune dysregulation, vasculopathy, and progressive fibrosis affecting the skin and internal organs. Although biologic therapies have expanded the therapeutic landscape of immune-mediated diseases, their impact in SSc has been uneven and remains difficult to interpret when viewed only on a drug-by-drug basis. This focused narrative review reappraises biologic therapies in SSc using a manifestation-based framework spanning cutaneous, pulmonary, vascular, gastrointestinal, musculoskeletal, and global or composite outcomes. Published evidence is most developed for selected cutaneous and pulmonary manifestations, particularly through B-cell depletion in selected cutaneous–pulmonary phenotypes and interleukin-6 blockade that attenuates pulmonary function decline in early inflammatory disease, whereas gastrointestinal and vascular manifestations have not yet shown comparable clinical evidence of benefit and remain insufficiently studied. We argue that this asymmetry not only reflects differences in trial design and endpoint selection, but also manifestation-specific pathobiology, disease stage, and the extent to which inflammatory, vascular, and fibrotic processes remain therapeutically modifiable. In particular, vasculopathy may represent an upstream pathogenic layer that constrains the disease-modifying capacity of biologics that primarily improve downstream inflammatory or fibrotic manifestations. We also highlight the relevance of Japanese contributions to the biologics literature in SSc and discuss future priorities, including manifestation-appropriate endpoint selection, early-disease enrichment, and biomarker-informed stratification. Overall, biologics have changed the treatment of SSc in a selective rather than global manner; embracing a manifestation-based view is now essential for both trial design and day-to-day therapeutic decision-making.