#367 PROTECT and NefIgArd two-year proteinuria and eGFR outcomes in adults with IgA nephropathy: matching-adjusted indirect comparison

Abstract

Abstract Background and Aims Immunoglobulin A (IgA) nephropathy is a rare kidney disorder characterized by deposition of IgA in the glomeruli causing progressive loss of kidney function and increased risk of kidney failure. In the absence of a head-to-head trial, this study used unanchored matching-adjusted indirect comparison (MAIC) of clinical trial data to compare two-year efficacy outcomes between Sparsentan in PROTECT and targeted-release formulation (TRF) budesonide plus real-world optimized and stable renin-angiotensin system inhibition (RASi) standard-of-care (SoC) in NefIgArd. Method We conducted an unanchored MAIC using individual patient level data from the PROTECT trial and aggregate data from the NefIgArd trial. Patients in the sparsentan arm of PROTECT were weighted to match key baseline characteristics of patients in the targeted-release formulation (TRF) budesonide + RASi SoC arm of NefIgArd based on publicly accessible, clinically pertinent baseline characteristics and prognostic factors using the method of moments. After weighting, percentage reduction of urine protein-creatinine ratio (UPCR) relative to baseline and two-year eGFR total slope (based on available data, chronic slope estimates are currently not available from NefIgArd) were estimated. A mixed model for repeated measures (MMRM) was used for UPCR relative percentage reduction and a random effect coefficient model for eGFR total slope. A two-tailed z-test with a pooled standard error was conducted for the indirect comparison. Results After assessing PROTECT and NefIgArd cross-trial characteristics on key outcome definitions, inclusion and exclusion criteria, and patient population, the two trials were considered sufficiently similar for unanchored MAIC. After weighting individual patient data from PROTECT, all matched baseline patient characteristics were well-balanced between arms of the two trials. Comparative results showed patients treated with sparsentan in PROTECT (−43.2% relative reduction in UPCR) exhibited a greater mean percentage reduction in proteinuria at two-years compared to TRF budesonide + RASi SoC (−30.7% relative reduction in UPCR), a relative percentage reduction of 18.1% (p = 0.03; Fig. 1A). For eGFR total slope, patients treated with sparsentan exhibited a slower decline in kidney function compared to TRF budesonide + RASi SoC, a difference of 0.54 ml/min/1.73 m2 per year; however, this difference was not statistically significant (p = 0.35; Fig. 1B). Conclusion Aligned to an earlier analysis of percentage reduction in proteinuria at 9-months (−37%, p < 0.0001 favoring sparsentan), our MAIC results show that sparsentan in PROTECT was associated with a greater relative percentage reduction in proteinuria at two-years compared to TRF budesonide plus real-world optimized and stable RASi SoC in NefIgArd. eGFR total slope for sparsentan in PROTECT was comparable to that reported for TRF budesonide plus real-world optimized and stable RASi SoC in NefIgArd. Results comparing chronic slope may provide a better indication of the long-term nephroprotective value of both therapies.