What are alternative treatments to sparsentan for focal segmental glomerulosclerosis (FSGS)?

Alternative Treatments to Sparsentan for FSGS

For adults with idiopathic FSGS and nephrotic syndrome, corticosteroids remain the first-line therapy, with calcineurin inhibitors (cyclosporine or tacrolimus) as the primary alternative for steroid-resistant or steroid-intolerant patients. 1

First-Line Therapy: Corticosteroids

The KDIGO guidelines recommend initiating treatment only in idiopathic FSGS with nephrotic syndrome 1:

• Prednisone 1 mg/kg/day (maximum 80 mg) or alternate-day 2 mg/kg (maximum 120 mg) 1, 2
• Continue high-dose for minimum 4 weeks, up to maximum 16 weeks until complete remission 1, 2
• After remission, taper slowly over 6 months 1

Critical caveat: Adults respond much slower than children—over 50% show steroid resistance even with prolonged treatment 3. Intolerance is particularly problematic in older patients with diabetes, obesity, or osteoporosis 3.

Second-Line: Calcineurin Inhibitors (CNIs)

For Steroid-Resistant FSGS

Cyclosporine is the best-evidenced option 1, 4:

• Dose: 3-5 mg/kg/day in divided doses for at least 4-6 months 1
• Target trough levels (C0): 125-175 ng/mL 4
• If partial/complete remission occurs, continue for at least 12 months, then slow taper 1
• Response rate: approximately 70% in steroid-resistant patients 3
• Major limitation: >50% relapse upon discontinuation 3

Tacrolimus is an alternative CNI 3:

• Starting dose: 0.1 mg/kg/day in two divided doses 2
• Use when cyclosporine's cosmetic side effects (hirsutism, gum hypertrophy) are unacceptable 1
• Similar efficacy to cyclosporine in smaller studies 3

Important warning: Avoid CNIs in patients with significant vascular/interstitial disease on biopsy or reduced eGFR 3. Monitor for CNI-induced nephropathy—50% develop severe lesions with prolonged use 4.

For Steroid-Intolerant Patients

CNIs should be considered as first-line therapy in patients with contraindications to high-dose corticosteroids (uncontrolled diabetes, psychiatric conditions, severe osteoporosis) 1, 2.

Third-Line Options

Mycophenolate Mofetil (MMF) + High-Dose Dexamethasone

For patients who don't tolerate cyclosporine 1:

• MMF 500-1000 mg twice daily (or 1200 mg/m²/day in children) 1, 2
• Combined with high-dose dexamethasone
• Evidence: One multicenter RCT showed 33% combined partial/complete remission at 12 months, with 18% relapse after discontinuation 3
• This represents very modest improvement with prolonged exposure 3

Rituximab

Reserved for refractory cases only 2, 5:

• Consider only in steroid-dependent FSGS with continuing frequent relapses despite optimal combinations of prednisone and corticosteroid-sparing agents, and/or serious adverse effects 2, 5
• Evidence for FSGS is limited compared to minimal change disease 3

Other Investigational Agents

The following have preliminary data but require confirmation in larger trials 6, 7, 8:

• Adalimumab (TNF-α inhibitor)
• Abatacept (CTLA-4 immunoglobulin)
• ACTH (corticotropin)
• High-dose galactose
• Plasmapheresis/immunoadsorption (uncontrolled series suggest potential benefit) 9

Essential Supportive Care (All Patients)

Regardless of immunosuppressive choice, maximize non-immunosuppressive therapy 10, 9:

RAS Blockade

• ACE inhibitor or ARB uptitrated to maximally tolerated dose 10
• Target proteinuria <1 g/day (disease-dependent) 10
• Monitor for 30% creatinine rise (acceptable and stable) 10
• Stop if progressive kidney function decline or refractory hyperkalemia 10

Blood Pressure Control

• Target systolic BP <120 mmHg using standardized office measurement 10

Lifestyle Modifications

• Sodium restriction <2.0 g/day 10
• Weight normalization
• Smoking cessation
• Regular exercise

Additional Considerations

• Statin therapy for persistent hyperlipidemia, especially with cardiovascular risk factors 10
• Potassium-wasting diuretics or potassium binders to enable RAS blockade 10

Treatment Algorithm

1. Confirm idiopathic FSGS (exclude secondary causes, consider genetic testing in young patients or family history) 2
2. Optimize supportive care (RAS blockade, BP control, lifestyle) for all patients
3. If nephrotic syndrome persists:
   • No contraindications → Prednisone (4-16 weeks high-dose)
   • Steroid contraindications → Cyclosporine as first-line
4. If steroid-resistant (no response after 8-16 weeks):
   • Cyclosporine 3-5 mg/kg/day for 4-6 months minimum
   • Alternative: Tacrolimus if cosmetic concerns
5. If CNI-intolerant or CNI-resistant:
   • MMF + high-dose dexamethasone
6. If refractory with severe symptoms:
   • Consider rituximab or investigational therapies

Key Pitfalls to Avoid

• Don't declare steroid resistance prematurely: Adults may require up to 16 weeks to respond 1, 2
• Don't use CNIs with advanced interstitial fibrosis: Risk of irreversible nephrotoxicity 3
• Don't stop CNIs abruptly: Taper slowly over months to minimize relapse risk 1, 4
• Don't neglect supportive care: RAS blockade and BP control are critical regardless of immunosuppression 10, 9
• Don't assume all FSGS is immunosuppression-responsive: Genetic forms (podocin, WT1, APOL1 high-risk) typically resist treatment 2, 11