Systemic sclerosis (SSc) interstitial lung disease (ILD) is among the leading causes of SSc-related morbidity and mortality. Tocilizumab (TCZ, anti-IL6RA) has demonstrated a reduced rate of pulmonary function decline in two phase 2/3 trials (faSScinate and focuSSced) in SSc-ILD patients. We performed transcriptome analysis of skin biopsy samples collected in the studies to decipher gene networks that were potentially associated with clinical responses to TCZ treatment. One module correlated with disease progression showed pharmacodynamic changes with TCZ treatment, and was characterized by plasma cell (PC) genes. PC signature gene expression levels were also significantly increased in both fibrotic SSc and IPF lungs compared to controls. scRNAseq analyses confirmed that PC signature genes were co-expressed in CD38 and CD138 expressing PC subsets in SSc lungs. These data provide insights into the potential role of PC in disease progression and mechanisms of action of TCZ in fibrotic interstitial lung diseases.

Objective

Tocilizumab (TCZ) has demonstrated lung function preservation in 2 randomized controlled trials in early systemic sclerosis (SSc). This effect has yet to be characterized in terms of radiographically evident quantitative lung involvement. We undertook this study to assess the impact of TCZ on lung function preservation in a post hoc analysis, stratifying treatment arms according to the degree of lung involvement.

Methods

The focuSSced trial was a phase III randomized placebo-controlled trial of TCZ in patients with SSc and progressive skin disease. Participants underwent baseline and serial spirometry along with high-resolution chest computed tomography at baseline and at week 48. Quantitative interstitial lung disease (QILD) and fibrosis scores were assessed by computer software. We classified QILD into the following categories of lung involvement: mild (>5-10%), moderate (>10-20%), and severe (>20%).

Results

Of 210 participants recruited for the trial, 136 patients (65%) had ILD. The majority of these patients (77%) had moderate-to-severe involvement (defined as >10% lung involvement). The TCZ arm demonstrated preservation of forced vital capacity percent predicted (FVC%) over 48 weeks (least squares mean change in FVC% = -0.1) compared to placebo (-6.3%). For mild, moderate, and severe QILD, the mean ± SD change in FVC% in the TCZ arm at 48 weeks were -4.1 ± 2.5% (n = 11), 0.7 ± 1.9% (n =19), and 2.1 ± 1.6% (n = 26), respectively, and in the placebo group were -10.0 ± 2.6% (n = 11), -5.7 ± 1.6% (n = 26), and -6.7 ± 2.0% (n = 16), respectively. Similar treatment-related preservation findings were seen independent of fibrosis severity.

Conclusion

TCZ in early SSc-associated ILD with progressive skin disease stabilized FVC% over 48 weeks, independent of the extent of radiographically evident QILD.

OBJECTIVES: To establish a framework by which experts define disease subsets in systemic sclerosis associated interstitial lung disease (SSc-ILD). METHODS: A conceptual framework for subclinical, clinical and progressive ILD was provided to 83 experts, asking them to use the framework and classify actual SSc-ILD patients. Each patient profile was designed to be classified by at least four experts in terms of severity and risk of progression at baseline; progression was based on 1-year follow-up data. A consensus was reached if ≥75% of experts agreed. Experts provided information on which items were important in determining classification. RESULTS: Forty-four experts (53%) completed the survey. Consensus was achieved on the dimensions of severity (75%, 60 of 80 profiles), risk of progression (71%, 57 of 80 profiles) and progressive ILD (60%, 24 of 40 profiles). For profiles achieving consensus, most were classified as clinical ILD (92%), low risk (54%) and stable (71%). Severity and disease progression overlapped in terms of framework items that were most influential in classifying patients (forced vital capacity, extent of lung involvement on high resolution chest CT [HRCT]); risk of progression was influenced primarily by disease duration. CONCLUSIONS: Using our proposed conceptual framework, international experts were able to achieve a consensus on classifying SSc-ILD patients along the dimensions of disease severity, risk of progression and progression over time. Experts rely on similar items when classifying disease severity and progression: a combination of spirometry and gas exchange and quantitative HRCT.