IgA nephropathy, often abbreviated IgAN, is the most common primary glomerular disease worldwide and a leading cause of kidney failure in young and middle-aged adults. The disease arises from a subtle but destructive immunological misstep: the body produces abnormally high quantities of galactose-deficient IgA1, a poorly glycosylated version of a common antibody. These aberrant molecules accumulate in the bloodstream, provoke the formation of immune complexes, and ultimately deposit in the glomeruli, the delicate filtering units of the kidney. The resulting inflammation and scarring progressively erode the kidney’s ability to filter waste, a process that can unfold silently over decades. Many patients reach advanced chronic kidney disease or dialysis before they fully grasp how much function they have lost, a reality that has made IgAN a notorious ‘silent’ threat in nephrology.

For decades, treatment options were blunt. Non-specific immunosuppression with systemic corticosteroids could slow the disease, but at the cost of exposing the entire body to high steroid doses, with well-documented risks including infections, diabetes, weight gain, and cardiovascular complications. The intellectual breakthrough behind Nefecon was anatomical rather than chemical. Recognizing that mucosal immunity, particularly in the gut-associated lymphoid tissue concentrated near the ileocecal region, drives much of the overproduction of galactose-deficient IgA1, researchers engineered a capsule coated to withstand stomach acid and release budesonide precisely where Peyer’s patches are densest. The drug then exerts a local immunomodulatory effect on the lymphoid tissue that seeds the disease, while first-pass hepatic metabolism limits systemic steroid exposure. It is, in effect, a precision strike on the disease’s immunological engine room.

The concept was validated in controlled settings by the phase 2b NEFIGAN trial and the pivotal phase 3 NefIgArd program, which demonstrated statistically significant proteinuria reduction and, in two-year results, meaningful preservation of estimated glomerular filtration rate. But clinical trials enroll selected patients under idealized conditions, and regulators and clinicians alike have increasingly demanded confirmation that the benefit translates to the messy, heterogeneous reality of routine practice. The Xinjiang study was designed to address exactly this gap. Between September 2024 and March 2025, the investigators consecutively enrolled 28 patients with biopsy-confirmed primary IgAN who had been treated with Nefecon for more than nine months, collecting standardized data on demographics, laboratory outcomes, and adverse events in a retrospective real-world cohort.

The headline results are dramatic. After nine months of therapy, mean proteinuria fell from 1.7 plus or minus 1.2 grams per day to 0.6 plus or minus 0.5 grams per day, a reduction of 55.8 percent. That figure matters enormously because proteinuria is one of the most powerful modifiable predictors of long-term renal prognosis in IgAN; cohort studies have repeatedly shown that each gram of persistent protein in the urine compounds the risk of progression toward kidney failure. Equally notable was the change in kidney function itself. Estimated glomerular filtration rate, the standard measure of how well the kidneys filter, improved from 80.3 to 86.2 mL/min/1.73 m2, a gain of roughly five percent. Any functional improvement during active autoimmune disease is unusual and suggests the treatment is not merely suppressing symptoms but genuinely interrupting inflammatory injury.

Perhaps the most clinically provocative finding concerns baseline proteinuria. Patients entered the study across a range of proteinuria levels, and Nefecon appeared to deliver renal protection regardless of where a patient started, with signals suggesting greater benefit when treatment was initiated earlier in the disease course. This challenges a lingering clinical conservatism in which the most aggressive therapies are reserved for patients already showing heavy proteinuria and declining function. If low-level proteinuria is treated as a warning sign rather than a tolerated quirk, the window in which kidney tissue can still be rescued widens considerably. The study’s authors suggest that this supports a strategy of early intervention following diagnosis, an approach now echoed in evolving international treatment guidance, including the KDIGO 2025 clinical practice guideline for IgA nephropathy.

Safety data from the cohort will reassure clinicians who have watched the therapeutic landscape expand rapidly. Seventeen of the 28 patients, or 60.7 percent, experienced at least one adverse event, but the spectrum was mild and predictable for a locally targeted steroid. The most common event was acne, affecting 21.4 percent of patients. Crucially, no severe adverse events and no treatment-related deaths were observed, and the tolerated profile contrasts sharply with the serious corticosteroid toxicities documented with systemic steroid regimens in earlier IgAN trials. Because Nefecon releases budesonide in the distal small intestine and is largely cleared on first pass through the liver, systemic exposure remains a fraction of what conventional oral prednisone produces, and this real-world dataset supports that pharmacokinetic advantage in routine use.

The study’s significance extends beyond a single drug. IgAN has recently become one of the most dynamic fields in nephrology, with endothelin receptor antagonists, SGLT2 inhibitors, and complement-targeted therapies all entering the treatment algorithm alongside Nefecon. Real-world evidence like this cohort study functions as a crucial bridge between regulatory trials and everyday clinical decision-making, confirming that the antiproteinuric effects seen in the randomized NefIgArd population, including the mainland China substudy, reproduce in a broader, unselected patient group. It also provides nephrologists with practical dosing-and-response expectations: a majority proteinuria reduction at nine months is a realistic and clinically meaningful benchmark when patients are treated under standard care conditions.

Limitations remain, and the investigators are appropriately measured about them. The cohort is small, retrospective, and drawn from a single center, and nine months, while sufficient to capture established treatment response, cannot reveal whether functional gains persist after therapy stops or whether the drug alters the long-term risk of kidney failure. These caveats notwithstanding, the consistency of the findings with the randomized trial evidence strengthens the case that Nefecon has earned a genuine place in routine care. For the millions of people living with IgA nephropathy worldwide, the message from this study is quietly radical: the disease can be attacked at its immunological source, the kidneys can be protected before they are irreversibly damaged, and treatment can begin early, safely, and effectively. As real-world experience accumulates, the era of watchful waiting in IgAN is steadily giving way to one of early, targeted intervention.

Subject of Research: Real-world effectiveness and safety of targeted-release budesonide (Nefecon) in primary IgA nephropathy across baseline proteinuria levels

Article Title: Effectiveness and Safety of Nefecon in Primary IgA Nephropathy Across Different Baseline Proteinuria Levels: A Real-World Study

Article References: Suolinge, C., Dema, C., Wu, X., Jiang, B., Lu, C., & Li, J. (2026). Effectiveness and Safety of Nefecon in Primary IgA Nephropathy Across Different Baseline Proteinuria Levels: A Real-World Study. Advances in Therapy. https://doi.org/10.1007/s12325-026-03784-0

Image Credits: AI Generated

DOI: 10.1007/s12325-026-03784-0

Keywords: IgA nephropathy, Nefecon, targeted-release budesonide, proteinuria, kidney function, estimated glomerular filtration rate, real-world evidence, galactose-deficient IgA1, chronic kidney disease, early intervention, nephrology, autoimmune kidney disease

IgA nephropathy, characterized by the deposition of abnormal immunoglobulin A (IgA) complexes in the glomeruli, stands as the most prevalent form of primary glomerulonephritis worldwide. This condition triggers chronic inflammation and damage within the kidney’s filtering units, leading to proteinuria and gradual loss of renal function. Despite being a leading cause of chronic kidney disease, IgAN remains underdiagnosed until patients present with advanced renal impairment, frequently making therapeutic intervention challenging and highlighting the critical need for disease-modifying treatments.

Zigakibart operates through selective inhibition of APRIL (A proliferation-inducing ligand), a cytokine integral to B cell activation and survival that drives the production of pathogenic galactose-deficient IgA1 (Gd-IgA1), a central factor implicated in IgAN pathogenesis. By interrupting this pathway, zigakibart aims to reduce the synthesis of nephritogenic IgA1, thereby halting or even reversing ongoing immune-mediated kidney injury.

The ADU-CL-19 trial enrolled 40 adult participants diagnosed with biopsy-confirmed IgAN who exhibited persistent proteinuria despite receiving the standard of care, including maximally tolerated renin-angiotensin system inhibitors (RASi). Patients were administered zigakibart biweekly, either through intravenous infusions or subcutaneous injections, for a duration extending to 100 weeks. This regimen sought to evaluate the antibody’s ability to induce remission of proteinuria and preservation of kidney function over an extended treatment period.

Remarkably, data from week 100 demonstrated a 60% reduction in proteinuria compared to baseline levels, signifying substantial attenuation of the pathological leakage of proteins through the glomerular filtration barrier. Notably, over half of the patients achieved proteinuria values below 500 mg per 24 hours, with nearly one-third of subjects reaching even deeper remission below 300 mg per 24 hours—benchmarks rarely attained with current therapeutic options.

Crucially, these proteinuria improvements were coupled with stable estimated glomerular filtration rate (eGFR) across all patient subgroups, an encouraging indicator that zigakibart not only ameliorates functional impairment but may also prevent progressive nephron loss. The sustained eGFR stabilization, even among patients with varying degrees of proteinuria response, strengthens the hypothesis that APRIL pathway blockade confers long-lasting renal protection beyond symptomatic control.

Serological analyses substantiated the mechanistic rationale behind zigakibart’s efficacy. Patients exhibited pronounced decreases in circulating immunoglobulins, including a 74% reduction in both total IgA and the pathogenic Gd-IgA1 subtype. This selective diminishment aligns with APRIL’s role in B cell maturation and underscores the antibody’s capacity to suppress production of disease-driving immune complexes.

From a safety standpoint, zigakibart was well tolerated throughout the study timeline. Most reported adverse events were mild to moderate in severity, with infections representing the most frequent but manageable side effect. Importantly, no treatment-related serious infections or discontinuations were observed, even amidst a backdrop of elevated COVID-19 prevalence in the regions where the trial was conducted. This tolerability profile is especially relevant given the immunomodulatory action of the drug.

These findings represent the longest duration of kidney function stabilization reported for any anti-APRIL agent in patients with IgAN, positioning zigakibart as a leading candidate for long-term disease management. Professor Jonathan Barratt, the lead investigator, emphasized that these data bolster confidence in zigakibart’s potential to serve as a cornerstone therapy that not only mitigates renal injury but also fundamentally modifies the disease trajectory.

Looking ahead, the ongoing global Phase 3 BEYOND study aims to extend and validate these outcomes in a larger, more diverse patient population. With primary endpoints focused on proteinuria reduction at 40 weeks and kidney function preservation through 104 weeks, this trial will provide critical insights into zigakibart’s utility in routine clinical practice. An open-label extension study, BEYONDx, is concurrently underway to assess sustained treatment effects and long-term safety.

The introduction of zigakibart signals a paradigm shift in IgAN therapeutics, setting the stage for targeted immunological interventions that address the underlying pathomechanisms rather than merely controlling symptoms. As the medical community eagerly anticipates further Phase 3 data, zigakibart offers a beacon of hope for the millions affected by this stealthy but devastating kidney disease.

Subject of Research:
IgA nephropathy (IgAN) treatment and long-term efficacy of anti-APRIL monoclonal antibody, zigakibart.

Article Title:
Long-term Phase 1/2 Study Demonstrates Sustained Efficacy and Safety of Zigakibart in IgA Nephropathy.

News Publication Date:
5 June 2025

Web References:
http://www.era-online.org

References:

1. Barratt J., Lee E.Y., Kim S.G., et al. (2025). Sustained Long-Term Efficacy and Safety of Zigakibart Over 100 Weeks in Patients with IgA Nephropathy. Presented at ERA Congress; 5 June 2025; Vienna, Austria.
2. Caster, D.J., King, L.S., Rovin, B.H., et al. (2024). The treatment of primary IgA nephropathy: Change, change, change. American Journal of Kidney Diseases, 83(2), 229–240.
3. Pitcher, D., Braddon, F., Hendry, B., et al. (2023). Long-Term Outcomes in IgA Nephropathy. Clinical journal of the American Society of Nephrology, 18(6), 727–738.
4. Myette J.R., Kano, T., Suzuki, H. et al. (2019). A Proliferation-Inducing Ligand (APRIL) targeted antibody is a safe and effective treatment of murine IgA nephropathy. Kidney International, 96(1):104-116.
5. Mathur M., Barratt J., Chacko, B., et al. (2024). A Phase 2 Trial of Sibeprenlimab in Patients with IgA Nephropathy. New England Journal of Medicine, 390:20-31.

Keywords:
IgA nephropathy, zigakibart, anti-APRIL antibody, proteinuria remission, kidney function stabilization, glomerular disease, monoclonal antibody therapy, disease-modifying treatment, clinical trial, immunoglobulin A1, APRIL pathway, renal medicine