Key Takeaway
With sparsentan approved as the first therapy for FSGS, the field has reached a turning point - but four durable unmet needs remain that physicians say any meaningful new entrant must address.
MarketVue® FSGS (U.S.) draws on in-depth interviews with U.S. nephrology KOLs and a national survey of practicing nephrologists conducted by REACH Market Research to document where existing options leave patients underserved. Across academic centers and community practices, physicians identified four persistent gaps that define the current treatment reality in focal segmental glomerulosclerosis.
Unmet Needs in FSGS
Therapies That Achieve a Deeper Proteinuria Lowering Response Than Current SOC
For most patients with FSGS, even optimized supportive care - including RAAS blockade and additional immunosuppression where appropriate - fails to achieve the depth of proteinuria reduction that nephrologists consider clinically meaningful. The gap between what current therapies can deliver and the proteinuria targets physicians aim for is wide, and it defines the floor of unmet need in this disease.
“If you say that my goal is to try to eliminate proteinuria or at least bring it – normal is what, like less than 200 mg to 300 mg, so at least get it down to 500 mg, the number of patients with FSGS who you give an ARB and they get to a proteinuria of less than 500 mg is close to zero.”— FSGS KOL
Options for Patients With Uncontrolled Disease Despite Optimized Treatment
A substantial proportion of patients with primary and genetic FSGS continue to have uncontrolled disease - defined as proteinuria remaining above goal and ongoing kidney function decline - even after optimized supportive care and any additional therapies considered appropriate. For these patients, nephrologists describe a limited menu of options and a deepening sense of therapeutic constraint.
“And they’re progressive, and they don’t respond to anything, and we keep them on the ACE and ARB and really just monitor unless they want to be in a clinical trial.”— FSGS KOL
Lack of Disease-Modifying Therapies
Current treatments for FSGS - including steroids, calcineurin inhibitors, and RAAS blockade - are non-specific and non-curative. They address symptoms and attempt to slow decline rather than targeting the underlying podocyte injury and fibrosis that drive disease progression. The absence of any agent with true disease-modifying potential represents a fundamental limitation in what physicians can offer their patients today.
“We don’t have any agents at this point. I mean there are studies that are ongoing to see if there could be disease-modifying therapies, but in terms of right now, we need to reduce the proteinuria using our steroids, maybe immunosuppression. That’s just focusing on the fibrosis part, the sclerosis part, right? That’s all we are doing.”— FSGS KOL
Lack of Targeted, Subtype-Specific Therapies
FSGS is not a single disease. It is a histologic pattern arising from distinct etiologies - primary, secondary, genetic, and APOL1-associated - each driven by different underlying mechanisms and requiring fundamentally different treatment strategies. Yet the current therapeutic toolkit treats these subtypes largely the same, leaving patients with subtype-specific disease, particularly those with genetic and secondary forms, without meaningful targeted options.
“FSGS is not a disease. It’s just scarring in the kidney. And so whenever somebody proposes a therapy, you really want to try to understand based on the mechanism of the therapy, what’s the group of patients that that’ll help.”— FSGS KOL
The Bottom Line
The KOL perspectives and survey data captured in this post offer a clinical view of the gaps nephrologists navigate every day in FSGS - and the standards they are setting for what meaningful progress must look like. The specific thresholds, prescribing dynamics, pipeline assessments, and strategic implications for teams developing or commercializing therapies in this space live in the full MarketVue® report.
About MarketVue®
MarketVue® is an opportunity assessment report that delivers KOL-informed strategic intelligence for life sciences teams operating in rare and niche disease markets. Each report integrates primary KOL research, market intelligence, and strategic analysis to answer the questions that matter most to development, commercial, and investment teams: where is and what is the size of the opportunity, what does it take to win, and how is the market about to change.