IgA Nephropathy After STOP-IgAN: Budesonide, Steroids, or Staying the Course
A single patient, six months into maximized supportive care for IgA nephropathy with proteinuria that won't come down further. The disagreement is whether a trial that argued against added therapy has been overtaken by a drug it never tested.
Priya K. is finishing a PhD in structural engineering and still runs half-marathons on weekends when her schedule allows it, which is partly why the gross hematuria fourteen months ago — bright red urine during an ordinary head cold — was so alarming: nothing about her life had prepared her to expect a kidney biopsy at twenty-eight. The biopsy, done four months after that episode, showed IgA nephropathy, MEST-C M1E0S0T0C0, and she has spent the last six months maximizing losartan and adding dapagliflozin, the standard first move before anyone talks about immunosuppression. Her proteinuria came down from 2.6 grams a day to 1.8 and then simply stopped moving, unchanged across her last two clinic visits, her blood pressure well controlled, her eGFR holding steady at 68.
That plateau is the actual decision point, and it lands on genuinely contested ground. STOP-IgAN randomized this question — adding immunosuppression on top of optimized supportive care — and split its two co-primary endpoints: the immunosuppression arm did reach full clinical remission more often, 17 percent against 5, but showed no advantage on the endpoint that matters more here, the proportion losing 15 or more mL/min of eGFR at three years, and it carried real added harm. A trial that buys a remission rate without buying kidney function is a thinner argument for escalation than a bare summary makes it sound. But STOP-IgAN never tested targeted-release budesonide, and that distinction matters mechanistically, not just as a technicality. Nefecon delivers corticosteroid specifically to the ileum, where the Peyer's patches implicated in pathogenic, poorly-galactosylated IgA production sit — a local, mucosal-immune target rather than a blunt systemic one. NefIgArd's own randomized trial, run after STOP-IgAN, found real proteinuria reduction and slowed eGFR decline on that targeted mechanism with a safety profile closer to placebo than to systemic steroids. Her plateau, at her age, with sixty or more years of kidney function still ahead of her to protect, is exactly the population NefIgArd was built around. She has asked, more than once, whether the half-marathons are doing her kidneys any favors or simply masking how she'd otherwise feel — a question with no real answer in the literature, but one that captures how much she wants a plan that does something rather than one that asks her to keep waiting on a number that has already told her, twice, that it isn't going to move on its own.
In clinic, at the six-month plateau
STOP-IgAN already ran this experiment — immunosuppression added to optimized supportive care, randomized. It bought a higher full-remission rate, I'll grant that, but no difference in eGFR loss at three years, and real added harm in the treatment arm. Her proteinuria plateau is disappointing; it isn't an emergency, and the trial closest to her actual situation bought a number rather than a kidney.
I'd push back gently on reading STOP-IgAN as the final word — the toxicity signal that trial found was largely driven by the original full-dose steroid protocol, and TESTING's own reduced-dose arm preserved the composite renal-outcome benefit while cutting that same infection risk substantially. A plateau after six months of optimized RAAS blockade is exactly the population TESTING enrolled.
Treating STOP-IgAN and TESTING as though they tested the same thing at the same dose isn't quite right — the safety picture changed materially once the steroid dose did.
Both of you are arguing from trials that predate the drug actually built to answer this exact question. NefIgArd tested targeted-release budesonide specifically because STOP-IgAN's real objection was systemic toxicity, not the principle of local immunomodulation — Nefecon delivers corticosteroid to the ileal Peyer's patches where the pathogenic, poorly-galactosylated IgA is actually produced, with plasma corticosteroid exposure much closer to placebo than to a systemic steroid course.
That trial found real proteinuria reduction and a slower eGFR-decline trajectory in a population that looks a great deal like her: preserved renal function, meaningful residual proteinuria despite maximized supportive care, decades of kidney function still worth protecting. It doesn't erase STOP-IgAN's caution — it answers it.
Agreed: start targeted-release budesonide for a 9-month course, with 24-hour urine protein and eGFR rechecked at 3 and 9 months. RAAS blockade and the SGLT2 inhibitor continue unchanged throughout.
The supportive-care-only position wasn't overruled so much as reframed — everyone agreed STOP-IgAN's caution against reflexive systemic immunosuppression escalation is sound, remission-rate signal notwithstanding, and that caution is exactly why a gut-targeted, lower-systemic-exposure drug was chosen over the systemic steroid option rather than added on top of it.