George Vasquez-Rios, MD, MSCR, FASN, is a nephrologist and glomerular disease specialist and director of the Glomerular & Genetic Diseases Center.

George Vasquez-Rios, MD

 enter the health system through internists, general nephrologists, and glomerular disease specialists alike, yet guidance on recognizing, staging, and treating these conditions remains scattered across journals, guidelines, and institutional resources. Patients managed only by general nephrologists, without access to a glomerular disease specialist, are less likely to receive a kidney biopsy or newer therapies, a gap tied to delayed diagnosis and treatment.¹

 built the Glomerular Diseases Collaborative (GD-C) Compendium to address fragmentation rather than a shortage of information, curating committee-reviewed guidance across 5 conditions: ANCA-associated vasculitis, 

, and membranous nephropathy. The compendium sits alongside, not in place of, clinical guidelines, moving faster than formal guideline development typically allows while curating landmark studies, a recognition-to-referral pathway, and practical guidance on prior authorization, referrals, and appeals.²

The GD-C Compendium is built to be actionable rather than encyclopedic, according to the American Society of Nephrology.² A dedicated recognition-to-referral pathway walks general nephrologists and internal medicine physicians through which tests to order and when to refer, while a separate library curates landmark clinical trial data as new glomerular disease therapies expand and grow more complex to prescribe.

The compendium is designed to serve 2 distinct audiences with different clinical questions: general clinicians deciding whether a case is glomerular disease at all, and glomerular disease specialists weighing newer therapies and monitoring strategies. George Vasquez-Rios, MD, MSCR, FASN, director of the Glomerular and Genetic Diseases Center at Renal Medicine Associates, helped shape the compendium's structure around homogenizing management regardless of a patient's point of entry into care. In the following interview, Vasquez-Rios discusses the origins of the GD-C Compendium and how it serves both general clinicians and glomerular disease specialists.

: What led to the creation of the GD-C Compendium, and what gap in existing resources was it meant to address?

George Vasquez-Rios, MD: The Glomerular Disease Collaborative is an initiative within the American Society of Nephrology. The Society is trying to ensure good care for patients regardless of where they enter the health system, whether they're seen by an internist, a general nephrologist, or a glomerular disease expert. 

We're trying to create a platform that allows physicians at different stages of expertise to learn more about these conditions: how to treat, when to refer, and what options are available. The problem was never a lack of information. We live in an era with a lot of information and a lot of great articles out there. The problem is fragmentation. 

The compendium is trying to serve as a platform with curated information, carefully reviewed by a board committee, that represents what we think is the most substantial and relevant information to guide the management of patients. 

We're not coming up with new information. We're intentionally broader than the clinical guidelines, because guidelines take time to develop. We intend to provide information and education to guide clinical management as much as we can in this novel and very dynamic field.

: What kind of resources does the compendium bring together, and which sections would you point clinicians to first?

George Vasquez-Rios, MD: As I mentioned, the compendium isn't meant to replace clinical guidelines. Those remain the most authoritative information for guiding patient management. We're curating studies, background education, and foundational material, along with information about newer therapies and clinical trials that can help enrich the management of…patients. 

There are a few sections I'd highlight. We provide information on disease biology and mechanisms of action for certain therapies, but we also have dedicated sections meant to make navigating patient management easier. For example, we have a glomerular disease recognition-to-referral section, intended to guide general nephrologists, clinicians, and even internal medicine doctors on how to recognize an active glomerular disease, what tests to start, and when to make referrals. 

We also dedicate sections to relevant articles published in recent years, landmark studies and landmark clinical trials, given how hard it is to find time to read through all the literature being published. It's also important to mention we're trying to incorporate patient voices, because we're not only looking to inform or educate physicians, but to empower patients. That's an evolving part of the compendium. And we talk about access to treatment. 

With these highly effective medications, there are nuances at the time of prescribing, such as when a medication is indicated, what the side effects are, and how to ensure patients can access these medications. One thing we provide is tips for navigating those issues: prior authorizations, referrals, appeals, and documentation that can help busy clinicians with that side of care.

: How does the compendium balance serving both general clinicians and glomerular disease specialists?

George Vasquez-Rios, MD: That's an important consideration, because these are physicians with different needs who manage different populations. A general nephrologist or primary care physician is often trying to answer questions like: is this a glomerular disease, how active is it, how should we approach testing or management? 

Those are the questions we're trying to address for that audience. A glomerular disease expert is asking different questions: what are the latest therapies, what evidence supports them, how do I monitor the effects of these medications? Those are more sophisticated, more complex questions.

 What we're trying to do with the compendium is help homogenize the management of these patients, regardless of where they entered the healthcare system. We recognize [patients with glomerular disease] are seen across a wide array of specialties, so it's important to have practical foundations and information on how to approach these patients. Hopefully, in the future, this becomes a dynamic resource that can also incorporate recommendations as the evidence emerges.

Editor’s Note: This transcript has been edited for grammar and clarity using artificial intelligence tools.

Monk B, Ewert B, Bomback AS, Gibson KL. Barriers to patients accessing specialized treatments for glomerular diseases. 

American Society of Nephrology. Glomerular Diseases Collaborative (GD-C) Compendium. Accessed September 22, 2026. 

https://epc.asn-online.org/projects/gd-c/

Articles

The ASN Glomerular Diseases Collaborative Compendium centralizes committee-reviewed, clinically actionable guidance to mitigate fragmented glomerular disease resources and variability in care pathways. It targets inequities seen when patients lack access to subspecialists, including lower biopsy rates and reduced uptake of newer therapies. Covering ANCA-associated vasculitis, IgA nephropathy, lupus nephritis, C3 glomerulopathy, and membranous nephropathy, it complements—not replaces—formal guidelines by updating faster and curating landmark trials, biology, and treatment access tools.

George Vasquez-Rios, MD, explains how the ASN's GD-C Compendium curates glomerular disease guidance for general clinicians and specialists alike.

How the ASN's GD-C Compendium Aims to Unify Glomerular Disease Care

An estimated 200 glomerular disease specialists practice across the US and Canada, with some states lacking an expert within 200 miles, a scarcity that puts real weight on how early general clinicians recognize a glomerular disease before a referral ever happens.¹

George Vasquez-Rios, MD, MSCR, FASN, director of the Glomerular and Genetic Diseases Center at Renal Medicine Associates, discussed how general clinicians can recognize glomerular disease earlier and navigate referral pathways as part of the 

‘s new Glomerular Diseases Collaborative (GD-C) Compendium, in an interview with 

You Don't Need to Be a GN Specialist to Identify Glomerular Disease Earlier

For more on the ASN's new GD-C Compendium itself and our conversation with George Vasquez-Rios, MD: 

New ASN Compendium Tackles Fragmented GN Care, With Vasquez-Rios, MD

When Should Glomerular Disease Be Suspected?

Vasquez-Rios pointed to unexplained proteinuria or hematuria, even when kidney function looks normal, as a specific, actionable trigger for workup.

"Whenever we see patients that are dealing with proteinuria and/or hematuria, meaning blood in the urine, and we don't have a clear etiology, a clear answer why this is happening, this should prompt urinalysis, renal ultrasound, additional evaluations for considerations of a glomerular disease, even when the kidney function is relatively preserved," Vasquez-Rios said.

That distinction matters given how specialist access is distributed. Research published in the 

Journal of the American Society of Nephrology

 in July 2025 found that patients managed only by general nephrologists, without access to a glomerular disease specialist, were less likely to receive a kidney biopsy or newer therapies, a gap the authors linked to delayed diagnosis and treatment.² 

Earlier recognition during the point of entry to care with the clinicians patients actually see first, in Vasquez-Rios's view, is one way to narrow that gap before geography or specialist availability becomes the limiting factor.

Vasquez-Rios framed reaching out to more experienced colleagues as a normal part of managing an evolving field, not a sign of a gap in a clinician's own knowledge.

"There is no shame and there is no problem with calling other folks with more experience to ask for advice or support. I see that happening all the time, and I think that's where we as a community need to work together to create that level of bidirectional discussions," Vasquez-Rios said.

He also noted that access barriers don't stop at referral. Prescribing decisions for newer glomerular disease therapies carry their own friction, from prior authorization to documentation, which is part of why the ASN's GD-C compendium built out a dedicated recognition-to-referral pathway alongside practical guidance on navigating access issues.

A Community Clinicians Don't Have to Navigate Alone

Vasquez-Rios's closing point was that clinicians managing glomerular disease patients don't have to do it in isolation.

"Nobody has to do this alone. We are a community," Vasquez-Rios said. He pointed to ASN's online communities, where complex cases, including acute kidney injury and 

 with or without glomerular disease involvement, are discussed regularly, along with planned efforts like journal clubs and interviews addressing specific clinical questions. 

"I swing by every now and then," he said. "We are all together in this, and we can really make it better for our patients."

Editor's Note: Vasquez-Rios reports no relevant disclosures.

American Society of Nephrology. Glomerular Diseases Collaborative (GD-C) Compendium. Accessed September 17, 2026. 

Videos

George Vasquez-Rios, MD, explains the barriers in GN care that ASN's new compendium may address.

 disease care means addressing not a shortage of research, but its fragmentation, scattered across specialties, guidelines, and clinical settings without one place to bring it together.¹

George Vasquez-Rios, MD, MSCR, FASN, Director of the Glomerular and Genetic Diseases Center at Renal Medicine Associates, discussed the origins and structure of the 

's Glomerular Diseases Collaborative (GD-C) Compendium in an interview with 

Addressing Fragmentation, Not a Lack of Information

The GD-C is an initiative within ASN built around a specific problem. According to Vasquez-Rios, there is not a shortage of information, but a fragmentation across the different points where a patient might enter the health system, whether through an internist, a general nephrologist, or a GN specialist.

"I think that the problem was never the lack of information. As a matter of fact, we live in an era where there's a lot of information, there are great articles out there. The issue is the fragmentation," Vasquez-Rios said. "The compendium is trying to serve as a platform that has curated information, carefully reviewed by a board committee, that represents what we think is the most substantial and relevant information to guide the management of patients."

Vasquez-Rios explained that the compendium is not a substitute for clinical guidelines, or a vehicle for new findings, but rather, it's designed to keep pace with new research for clinical management. 

"We are not coming up with newer information," Vasquez-Rios said. "We intentionally are broader than the clinical guidelines, because they take some time to actually develop. We intend to provide information and education to guide clinical management as much as we can for this novel and very dynamic field."

The compendium's professional resources are organized around 5 conditions, ANCA-associated vasculitis,

, and membranous nephropathy, alongside a dedicated recognition-to-referral pathway and a separate set of patient education materials.¹

"We have a glomerular disease recognition-to-referral [section], which is intended to guide general nephrologists, clinicians, even internal medicine doctors, on how to recognize an active glomerular disease, what tests to start taking on these patients, and when to make referrals," Vasquez-Rios said. 

The compendium also curates landmark studies and clinical trials, an intentional response, he said, to how much is now being published in a field where clinicians have little time to keep up.

Access is a recurring theme because several glomerular disease therapies are highly effective but complex to prescribe. Thus, the compendium includes practical guidance on prior authorizations, referrals, and appeals. 

"We provided tips and tricks to navigate these issues all the way from prior authorizations, referrals, appeals, and even provide some documentation that can help busy clinicians with this aspect of care," Vasquez-Rios said.

Condition-specific sections: ANCA-associated vasculitis, IgAN, lupus nephritis, C3G, membranous nephropathy

A recognition-to-referral pathway for general clinicians

Curated landmark studies and emerging clinical trial data

Practical guidance on prior authorization, referrals, and appeals

Patient education materials, with an evolving effort to incorporate patient voices directly

Built to Serve General Clinicians and GN Specialists Alike

Vasquez-Rios described the compendium as intentionally built for 2 different audiences with 2 different sets of questions. A general nephrologist or primary care physician, he said, is often asking whether a case is a glomerular disease at all, how active it appears to be, and how to begin testing or management. A GN specialist is typically further along, asking what the latest therapies are, what evidence supports them, and how to monitor a patient's response.

"What we're trying to do with this compendium is try to homogenize a little bit the management of these patients, regardless of where the point of entry to the healthcare system was," Vasquez-Rios said. "We recognize that glomerular disease patients are seen by a wide array of specialties, so it is important to have some practical foundations and information about how to approach these patients."

The compendium is meant to function less like a static reference and more like a living resource clinicians return to, Vasquez-Rios said, with content he expects to update roughly every 6 months, faster for disease areas advancing quickly, such as IgAN and lupus nephritis.

"We're living a unique era in nephrology, especially in the management of glomerular diseases... there's a lot of unknowns as well in the management of these patients and the use of these medications," Vasquez-Rios said. "As therapies become available, we intend not only to include the scientific evidence, but also some practical information."

That update process, he said, is built around a feedback loop rather than a fixed editorial board, with contributions from physicians, general practitioners, GN experts from both community practice and academia, and researchers. 

"That allows us to really build up more solid information... It’s all a process of learning, trial, error, learning again, and doing it better the next time," Vasquez-Rios said.

Monk B, Ewert B, Bomback AS, Gibson KL. Barriers to Patients Accessing Specialized Treatments for Glomerular Diseases. 

A new ASN compendium curates scattered GN care guidance into one living resource, says nephrologist George Vasquez-Rios, MD

The April 2026 US Food and Drug Administration approval of sparsentan (Filspari) marked the first approved therapy specifically indicated for focal segmental glomerulosclerosis (FSGS), a rare glomerular disease associated with progressive kidney function decline and a substantial risk of kidney failure.

Supported by data from the phase 3 DUPLEX trial, the approval introduced a long-awaited treatment option for a disease area that has historically relied on supportive care and off-label immunosuppressive therapies. The approval has prompted important discussions among nephrologists about how to interpret proteinuria reduction, incorporate sparsentan into treatment algorithms, and identify the patients most likely to benefit from therapy.

 spoke with George Vasquez-Rios, MD, MSCR, FASN, nephrologist and glomerular disease specialist and director of the Glomerular & Genetic Diseases Center. In this Q&A, Vasquez-Rios discusses sparsentan's mechanism of action, the clinical significance of proteinuria reduction, and how the approval may reshape care for patients with FSGS.

HCPLive: For decades, FSGS has lacked an FDA-approved disease-specific therapy. How does the approval of sparsentan change the standard of care, and what does success now look like for these patients?

 In the past, FSGS has been managed with foundational therapies such as renin-angiotensin system blockade and, in cases of immune-mediated disease, immunosuppression to achieve meaningful reductions in proteinuria. With the addition of sparsentan to the treatment landscape, we now have another option to effectively reduce proteinuria and potentially modify disease progression.

Reductions in proteinuria have consistently been associated with improved kidney outcomes, so having a medication that can help us achieve those reductions without necessarily exposing patients to the adverse effects of immunosuppression is a major step forward for the management of FSGS.

HCPLive: Where do you see sparsentan fitting relative to current standard approaches such as RAS blockade and immunosuppressive therapy?

 Sparsentan has the potential to take the place of traditional RAS blockade in many patients. Conventional therapies primarily target intraglomerular pressure, which is important for blood pressure control and reducing proteinuria.

However, sparsentan is a dual endothelin and angiotensin receptor antagonist, meaning it targets 2 important mechanisms. In addition to addressing intraglomerular pressure, it also affects podocyte biology. Podocytes express endothelin receptors, and excessive activation of these pathways contributes to oxidative stress, inflammation, fibrosis, and ultimately proteinuria.

By targeting both pathways simultaneously, sparsentan offers a unique mechanism that addresses key drivers of kidney injury in FSGS.

HCPLive: How should clinicians think about sparsentan's dual endothelin and angiotensin pathway inhibition in the context of FSGS biology?

 FSGS is a syndrome rather than a single disease and includes multiple subtypes, including primary, genetic, and secondary forms. Regardless of the underlying cause, podocyte injury is a central feature of disease progression.

The fact that sparsentan reduces proteinuria while also helping preserve kidney function is very attractive. That said, it should not replace immunosuppressive therapies in patients with primary FSGS, where immune dysregulation remains a key component of disease biology.

Instead, sparsentan can serve as an important foundational therapy that clinicians can initiate early while evaluating patients and making decisions regarding additional treatments.

HCPLive: In the phase 3 DUPLEX trial, sparsentan did not meet its primary endpoint for eGFR decline. How are clinicians interpreting that result alongside the proteinuria reductions observed in the study?

 The DUPLEX trial represented an important milestone for FSGS research. One of the challenges is that FSGS is an extremely heterogeneous condition. Even with careful evaluation, it can be difficult to distinguish primary, genetic, and secondary forms of disease, and each subgroup may follow a different clinical trajectory.

As a result, capturing meaningful differences in long-term eGFR outcomes across a heterogeneous patient population can be difficult. We also need to consider the acute hemodynamic effects of treatment separately from chronic eGFR slope effects. When both are analyzed together, there is the potential to underestimate the long-term clinical benefit of a therapy.

Importantly, open-label extension data have demonstrated that patients who achieved early proteinuria reductions with sparsentan experienced better long-term kidney outcomes. Programs such as PARASOL have also helped improve our understanding of clinically meaningful endpoints in FSGS and contributed to the FDA's recognition of proteinuria reduction as an important therapeutic target.

HCPLive: Which patients with FSGS are most likely to benefit from sparsentan?

 Patients with persistent proteinuria despite standard therapies are among the most likely to benefit. Many patients remain above target proteinuria levels despite treatment with RAS blockade, SGLT2 inhibitors, and other interventions.

Some patients are also unable to tolerate combinations of therapies because of blood pressure limitations. In those situations, sparsentan offers an opportunity to achieve meaningful proteinuria reduction through dual pathway inhibition while potentially reducing treatment burden.

Patients with primary FSGS may benefit as part of a broader treatment strategy, and emerging evidence also suggests benefit in patients with genetic forms of FSGS. Overall, I think sparsentan should be considered across a broad range of patients with proteinuric FSGS.

HCPLive: Is there anything else clinicians should keep in mind following the approval of sparsentan?

 FSGS remains a challenging condition that requires careful clinical evaluation to determine the underlying mechanism of disease. Patients with primary, immune-mediated FSGS often present with abrupt-onset proteinuria and may require immunosuppressive therapy. Other patients may have a more gradual decline in kidney function suggestive of secondary or genetic disease.

A detailed clinical history remains essential. Beyond establishing foundational therapies, including sparsentan, clinicians should focus on identifying the underlying disease process and intervening early to modify long-term outcomes.

The advances we've seen through PARASOL and other research efforts have improved our understanding of meaningful treatment targets in FSGS. While additional evidence continues to emerge, incorporating therapies that effectively reduce proteinuria and stabilize kidney function is an important step toward improving outcomes for these patients. 

Editor’s Note: Vasques Rios reports no relevant disclosures. 

Hillenbrand A. FDA Approves Sparsentan for Focal Segmental Glomerulosclerosis. HCPLive. Published April 13, 2026. Accessed June 1, 2026. 

https://www.hcplive.com/view/fda-approves-sparsentan-for-focal-segmental-glomerulosclerosis

Rheault MN, Alpers CE, Barratt J, et al. Sparsentan versus Irbesartan in Focal Segmental Glomerulosclerosis. 

FDA approval of sparsentan in April 2026 established the first disease-specific therapy for focal segmental glomerulosclerosis (FSGS), shifting management beyond supportive care and off-label immunosuppression. As a dual endothelin and angiotensin receptor antagonist, sparsentan targets intraglomerular hemodynamics and podocyte endothelin signaling implicated in oxidative stress, inflammation, and fibrosis. Although the DUPLEX phase 3 trial missed its primary eGFR endpoint, robust proteinuria reductions and extension data support proteinuria as a clinically meaningful surrogate linked to improved long-term kidney outcomes.

A clinician explains how sparsentan is changing treatment strategies for patients with FSGS.