#2459 Matching-adjusted indirect comparison of eGFR in patients with immunoglobulin A nephropathy treated with Nefecon (TRF budesonide) or sparsentan
Authors: Reich Heather , Patel Mit , Kopiec Agnieszka , Fu Shuai , Hummel Noemi , Lafayette Richard 
Published: May 2024

Abstract

Background and Aims
Primary immunoglobulin A nephropathy (IgAN) is an immune-mediated disease that can lead to kidney failure, need for dialysis and kidney transplantation, and early death. IgAN is the most common type of primary glomerulonephritis globally, with an estimated worldwide incidence of 2.5 per 100 000 individuals per year. Estimated glomerular filtration rate (eGFR) is a measure of renal function and is accepted as a surrogate endpoint for clinical trials evaluating kidney function deterioration. In December 2023, the US Food and Drug Administration (FDA) granted full approval to Nefecon (marketed as Tarpeyo® by Calliditas Therapeutics), a targeted-release formulation of budesonide, to reduce the loss of kidney function in adults with IgAN at risk of disease progression, based on the Phase 3 NefIgArd clinical trial. In February 2023, sparsentan (marketed as Filspari™ by Travere Therapeutics) was granted accelerated approval by the FDA to reduce proteinuria in adults with primary IgAN at risk of rapid disease progression, generally a urine protein–creatinine ratio (UPCR) ≥1.5 g/g, based on the Phase 3 PROTECT study. Matching-adjusted indirect comparison (MAIC) is a widely accepted and relevant methodology for comparing treatments across trials in the absence of head-to-head comparisons. In this analysis, we aimed to compare the effects of Nefecon and sparsentan on kidney function deterioration in patients with IgAN, as assessed by eGFR.

Method
An anchored MAIC was performed to estimate the relative effect of Nefecon and sparsentan on the absolute eGFR change from baseline at 9, 12 and 24 months, with common comparators of optimized renin–angiotensin system inhibition for NefIgArd and irbesartan for PROTECT. Patient-level data from NefIgArd were used to select a population matched to PROTECT, and the following baseline characteristics were used to determine the weights: mean age (years), sex (% male), race (% white), mean eGFR (mL/min/1.73 m2), mean UPCR (g/g), urine albumin–creatinine ratio (UACR) (% with UACR &gt;1.1 g/g), and urinary protein excretion (% with urinary protein excretion &gt;1.8 g/day). Absolute change in eGFR was analyzed using a mixed model for repeated measures (MMRM) method, including baseline, 3-, 6-, 9-, 12-, 18- and 24-month data, baseline eGFR, baseline eGFR-by-time interaction, treatment, and treatment-by-time interaction. The MAIC weights were incorporated into the MMRM. A Bayesian fixed-effects network meta-analysis was performed on the relative effect from PROTECT and the weighted relative effect from NefIgArd, measured by the estimated absolute change from baseline in eGFR.

Results
The matching-adjustment of the NefIgArd patient population to the PROTECT population is shown in Table 1. The weighted NefIgArd population exhibits very similar baseline characteristics to the PROTECT population. The effective sample size of the weighted NefIgArd population is 208. Results from the anchored MAIC showed statistically and clinically significant favorable effects of Nefecon versus sparsentan on eGFR for all time points analyzed (Fig. 1). Mean differences in the absolute change in eGFR of 5.68 mL/min/1.73 m2 (95% credible interval [Crl] 3.14, 8.20; p &lt; 0.001), 3.48 mL/min/1.73 m2 (95% Crl 0.97, 5.97; p = 0.006) and 3.28 mL/min/1.73 m2 (95% Crl 0.02, 6.51; p = 0.048) were observed when comparing Nefecon with sparsentan at 9 months vs 36 weeks, 12 months vs 48 weeks, and 24 months vs 106 weeks, respectively.

Conclusion
After accounting for differences in the patient populations from the NefIgArd and PROTECT trials, the anchored MAIC showed that treatment with Nefecon 16 mg/day for 9 months was associated with greater eGFR benefit compared with continuous treatment with sparsentan 400 mg/day over 2 years, with significant differences observed as early as 9 months after treatment initiation and sustained up to 2-years of follow-up.