Proteins meeting significance criteria for fold change in CERES participants who died, using three normalization formats.

Proteins meeting significance criteria for fold change in CERES participants who died, using three normalization formats.</p

Biological and technical variability of SomaScan.

Short-term biological and intra-assay CVs for 4802 proteins are shown in 4 study participants who had samples available for both types of CVs from the CERES cohort.</p

Orthogonal correlations for aptamer and traditional assays in CERES participants.

Spearman rho correlations were analyzed for aptamer and traditional assays. Aptamer measures were analyzed in three data formats: raw data, median normalized, and ANML. X-axes show the aptamer measure in relative fluorescence units (RFU), and the y-axes show the traditional assay. CRP: c-reactive protein. FGF23: fibroblast growth factor 23. NT-proBNP: N-terminal pro-B-type natriuretic peptide. PTH: parathyroid hormone.</p

Technical and biological variability of somascan in plasma samples of patients with kidney failure.

Coefficient of variation (CV) and spearman rho correlations between pairs of samples are shown above. Data are from CERES study with the exception of long-term within-subject variability, calculated from CRIC data.</p

SomaScan technical information.

BackgroundPatients with kidney failure suffer high mortality, and we currently lack markers for risk stratification for these patients. We carried out a quality control study of a modified aptamer assay (SomaScan v.4.0) that measures ~ 5000 proteins, in preparation for a larger study using this platform in cohorts with kidney failure.MethodsForty participants from the Cardiac, Endothelial Function and Arterial Stiffness in End-Stage Renal Disease (CERES study) were selected to analyze technical and short-term biological variability, orthogonal correlations and differential protein expression in plasma from patients who died during 2.5 year follow-up. Long-term (one year) variability was studied in 421 participants in the Chronic Renal Insufficiency Cohort. We evaluated 4849 aptamers (4607 unique proteins) using data formats including raw data and data formatted using Adaptive Normalization by Maximum Likelihood (ANML), an algorithm developed for SomaScan data in individuals with normal kidney function.ResultsIn ANML format, median[IQR] intra-assay coefficient of variation (CV) was 2.38%[1.76, 3.40] and inter-assay CV was 7.38%[4.61, 13.12]. Short-term within-subject CV was 5.76% [3.35, 9.72]; long-term CV was 8.71%[5.91, 13.37]. Spearman correlations between aptamer and traditional assays for PTH, NT-proBNP, FGF-23 and CRP were all > 0.7. Fold-change (FC) in protein levels among non-survivors, significant after Bonferroni correction, included SVEP1 (FC[95% CI] 2.14 [1.62, 2.82]), keratocan (1.74 [1.40, 2.15]) and LanC-like protein 1 (0.56 [0.45, 0.70]). Compared to raw aptamer data, technical and short-term biological variability in paired samples was lower in ANML-formatted data. ANML formatting had minimal impact on orthogonal correlations with traditional assays or the associations of proteins with the phenotype of mortality.ConclusionsSomaScan had excellent technical variability and low within-subject short-term variability. ANML formatting could facilitate comparison of biomarker results with other studies that utilize this format. We expect SomaScan to provide novel and reproducible information in patients with kidney failure on dialysis.</div

S2 File -

S2 Table 1 Proteins Excluded From Variability Analyses. S2 Table 2 Baseline Characteristics of CRIC Participants with Kidney Failure on Hemodialysis. S2 Table 3 Proteins with Intra-assay CV>20% Using Raw or ANML Data Format. S2 Table 4 Proteins with Inter-assay CV>40% Using Raw or ANML Data Format. S2 Table 5 Short-term Biological Variability Measured Separately in 4 CERES Participants. S2 Table 6 Long-term Variablity of Proteins in 421 CRIC Participants: Raw Data Format. S2 Table 7 Long-term Variablity of Proteins in 421 CRIC Participants: ANML Data Format. S2 Table 8 Correlations of Fold Change and P-values of Proteins in Non-survivors. S2 Table 9 Fold Change (FC) in Protein Level in Non-Survivors Compared to Survivors Using Raw Data. S2 Table 10 Fold Change (FC) in Protein Level in Non-Survivors Compared to Survivors Using Median Normalized Data. (ZIP)</p

Fold Change (FC) in protein levels among non-survivors compared to survivors in 40 CERES participants.

Fold Change (FC) in protein levels among non-survivors compared to survivors in 40 CERES participants.</p

Baseline characteristics of 40 participants with kidney failure.

Baseline characteristics of 40 participants with kidney failure.</p

Efficacy and safety of sparsentan versus irbesartan in patients with IgA nephropathy (PROTECT): 2-year results from a randomised, active-controlled, phase 3 trial

Background Sparsentan, a novel, non-immunosuppressive, single-molecule, dual endothelin angiotensin receptor antagonist, significantly reduced proteinuria versus irbesartan, an angiotensin II receptor blocker, at 36 weeks (primary endpoint) in patients with immunoglobulin A nephropathy in the phase 3 PROTECT trial's previously reported interim analysis. Here, we report kidney function and outcomes over 110 weeks from the double-blind final analysis. Methods PROTECT, a double-blind, randomised, active-controlled, phase 3 study, was done across 134 clinical practice sites in 18 countries throughout the Americas, Asia, and Europe. Patients aged 18 years or older with biopsy-proven primary IgA nephropathy and proteinuria of at least 1·0 g per day despite maximised renin–angiotensin system inhibition for at least 12 weeks were randomly assigned (1:1) to receive sparsentan (target dose 400 mg oral sparsentan once daily) or irbesartan (target dose 300 mg oral irbesartan once daily) based on a permuted-block randomisation method. The primary endpoint was proteinuria change between treatment groups at 36 weeks. Secondary endpoints included rate of change (slope) of the estimated glomerular filtration rate (eGFR), changes in proteinuria, a composite of kidney failure (confirmed 40% eGFR reduction, end-stage kidney disease, or all-cause mortality), and safety and tolerability up to 110 weeks from randomisation. Secondary efficacy outcomes were assessed in the full analysis set and safety was assessed in the safety set, both of which were defined as all patients who were randomly assigned and received at least one dose of randomly assigned study drug. This trial is registered with ClinicalTrials.gov, NCT03762850. Findings Between Dec 20, 2018, and May 26, 2021, 203 patients were randomly assigned to the sparsentan group and 203 to the irbesartan group. One patient from each group did not receive the study drug and was excluded from the efficacy and safety analyses (282 [70%] of 404 included patients were male and 272 [67%] were White) . Patients in the sparsentan group had a slower rate of eGFR decline than those in the irbesartan group. eGFR chronic 2-year slope (weeks 6–110) was −2·7 mL/min per 1·73 m2 per year versus −3·8 mL/min per 1·73 m2 per year (difference 1·1 mL/min per 1·73 m2 per year, 95% CI 0·1 to 2·1; p=0·037); total 2-year slope (day 1–week 110) was −2·9 mL/min per 1·73 m2 per year versus −3·9 mL/min per 1·73 m2 per year (difference 1·0 mL/min per 1·73 m2 per year, 95% CI −0·03 to 1·94; p=0·058). The significant reduction in proteinuria at 36 weeks with sparsentan was maintained throughout the study period; at 110 weeks, proteinuria, as determined by the change from baseline in urine protein-to-creatinine ratio, was 40% lower in the sparsentan group than in the irbesartan group (−42·8%, 95% CI −49·8 to −35·0, with sparsentan versus −4·4%, −15·8 to 8·7, with irbesartan; geometric least-squares mean ratio 0·60, 95% CI 0·50 to 0·72). The composite kidney failure endpoint was reached by 18 (9%) of 202 patients in the sparsentan group versus 26 (13%) of 202 patients in the irbesartan group (relative risk 0·7, 95% CI 0·4 to 1·2). Treatment-emergent adverse events were well balanced between sparsentan and irbesartan, with no new safety signals. Interpretation Over 110 weeks, treatment with sparsentan versus maximally titrated irbesartan in patients with IgA nephropathy resulted in significant reductions in proteinuria and preservation of kidney function.</p