Quantitative assessment of the extent of interstitial lung disease in patients with systemic sclerosis and levels of certain proteins in bronchoalveolar lavage samples have potential for predicting mortality and disease progression, according to two analyses of data from the Scleroderma Lung Study I and II.
Dr Elizabeth Volkmann
The analyses, presented at the annual European Congress of Rheumatology, aim to improve current prognostic abilities in patients with systemic sclerosis–interstitial lung disease (SSc-ILD). Although forced vital capacity (FVC) is commonly used as a biomarker for survival in many SSc-ILD trials, other factors can affect FVC, such as respiratory muscle weakness and skin fibrosis. Further, FVC correlates poorly with patient-reported outcomes, explained first author Elizabeth Volkmann, MD, director of the Scleroderma Program at the University of California, Los Angeles (UCLA), and the founder and co-director of the UCLA Connective Tissue Disease–Related Interstitial Lung Disease Program.
Volkmann presented two studies that investigated the potential of radiographic and protein biomarkers for predicting mortality and identifying patients at risk for ILD progression. The biomarkers may also help to identify patients who would benefit most from immunosuppressive therapy.
The first study found that tracking the quantitative extent of ILD (QILD) over time with high-resolution CT (HRCT) predicted poorer outcomes and could therefore act as a surrogate endpoint for mortality among patients with SSc-ILD. The other study identified associations between specific proteins from bronchoalveolar lavage (BAL) and the likelihood of ILD progression, although some associations were treatment dependent.
Dr Jacob van Laar
Jacob M. van Laar, MD, PhD, professor of rheumatology at the University Medical Center Utrecht, Utrecht, the Netherlands, who was not involved in the study, found the results intriguing and noted the importance of further validation in research before these biomarkers are considered for clinical use.
“It would be wonderful if we can tailor therapy based on BAL biomarkers in the future, as clinicians often struggle to decide on selection, timing, and duration of immunosuppressive treatment,” Van Laar told Medscape Medical News. “This has become even more relevant with the introduction of new drugs such as nintedanib.”
Extent of ILD Progression as a Surrogate for Mortality
Scleroderma Lung Study I involved 158 patients with SSc-ILD who were randomly assigned to receive either cyclophosphamide or placebo for 12 months. Scleroderma Lung Study II included 142 patients with SSc-ILD who were randomly assigned to receive either mycophenolate for 24 months or cyclophosphamide for 12 months followed by placebo for 12 months.
The researchers calculated QILD in the whole lung at baseline, at 12 months in the first trial, and at 24 months in the second trial. However, only 82 participants from the first trial and 90 participants from the second trial underwent HRCT. Demographic and disease characteristics were similar between the two groups on follow-up scans.
Follow-up continued for 12 years for patients in the first trial and 8 years in the second. The researchers compared survival rates between the 41% of participants from the first study and 31% of participants from the second study who had poorer QILD scores (at least a 2% increase) with the participants who had stable or improved scores (less than 2% increase).
Participants from both trials had significantly poorer long-term survival if their QILD scores had increased by at least 2% at follow-up (P = .01 for I; P = .019 for II). The association was no longer significant after adjustment for baseline FVC, age, and modified Rodnan skin score in the first trial (hazard ratio [HR], 1.98; P = .089), but it remained significant for participants of the second trial (HR, 3.86; P = .014).
“Data from two independent trial cohorts demonstrated that radiographic progression of SSc-ILD at 1 and 2 years is associated with worse long-term survival,” Volkmann told attendees.
However, FVC did not significantly predict risk of mortality in either trial.
“To me, the most striking finding from the first study was that change in QILD performed better as a predictor of survival than change in FVC,” Van Laar told Medscape Medical News. “This indicates QILD is fit for purpose and worth including in future clinical trials.”
Limitations of the study included lack of HRCT for all participants in the trials and the difference in timing (1 year and 2 years) of HRCT assessment between the two trials. The greater hazard ratio for worsened QILD in the second trial may suggest that assessment at 2 years provides more reliable data as a biomarker, Volkmann said.
“QILD may represent a better proxy for how a patient feels, functions, and survives than FVC,” she said.
Treatment-Dependent Biomarkers for Worsening Lung Fibrosis
In the second study, the researchers looked for any associations between changes in the radiographic extent of SSc-ILD and 68 proteins from BAL.
“Being able to risk-stratify patients with interstitial lung disease at the time of diagnosis and predict which patients are likely to have a stable vs progressive disease course is critical for making important treatment decisions for these patients,” Volkmann told attendees.
The second study she presented involved Scleroderma Lung Study I. Of the 158 participants, 144 underwent a bronchoscopy, yielding BAL protein samples from 103 participants. The researchers determined the extent of radiographic fibrosis in the whole lung with quantitative imaging analysis of HRCT of the chest at baseline and 12 months.
Although the researchers identified several statistically significant associations between certain proteins and changes in radiographic fibrosis, “baseline protein levels were differentially associated with the course of ILD based on treatment status,” she told attendees.
For example, increased levels of the following proteins were linked to poor radiographic fibrosis scores for patients who received placebo:
granulocyte-macrophage colony-stimulating factor (GM-CSF)
monocyte chemoattractant protein (MCP)-3
chemokine ligand (CCL)-5
transforming growth factor (TGF)-beta
hepatocyte growth factor
stem cell factor
Yet increases in these proteins predicted improvement in radiographic fibrosis in patients who had taken cyclophosphamide.
Independently of treatment, the researchers also identified an association between higher levels of fractalkine and poorer radiographic fibrosis scores and between higher IL-7 levels and improved radiographic fibrosis scores.
After adjusting for treatment arm and baseline severity of ILD, significant associations remained between change in radiographic fibrosis score and IL-1, MCP-3, surfactant protein C, IL-7 and CCL-5 levels.
“Biomarker discovery is really central to our ability to risk stratify patients with SSc-ILD,” Volkmann told attendees. “Understanding how biomarkers predict outcomes in treated and untreated patients may improve personalized medicine to patients with SSc-ILD and could also reveal novel treatment targets.”
Van Laar told Medscape Medical News that this study’s biggest strength lay in its large sample size and in the comprehensiveness of the biomarkers studied.
“The findings are interesting from a research perspective and potentially relevant for clinical practice, but the utility of measuring biomarkers in BAL should be further studied for predictive value on clinical endpoints,” Van Laar said. “BAL is an invasive procedure [that] is not routinely done.”
The research was funded by the National Institutes of Health. Volkmann has consulted for Boehringer Ingelheim and received grant funding from Corbus, Forbius, and Kadmon. Van Laar has received grant funding or personal fees from Arthrogen, Arxx Therapeutics, AstraZeneca, Bristol-Myers Squibb, Eli Lilly, Gesynta, Leadiant, Merck Sharp & Dohme, Roche, Sanofi, and Thermofisher.
Tara Haelle is an independent science journalist based in Texas who writes about medical research. Find her at @tarahaelle.