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 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, and the founder and codirector of the UCLA connective tissue disease–related interstitial lung disease program.
Dr. 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 M. van Laar
Jacob M. van Laar, MD, PhD, professor of rheumatology at the University Medical Center 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,” Dr. van Laar told this news organization. “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, 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,” Dr. 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,” Dr. van Laar said in an interview. “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, Dr. Volkmann said.
“QILD may represent a better proxy for how a patient feels, functions, and survives than FVC,” she said.