Abstract: FR-PO0829
Adaptive Phase 2/3 Study for PCS499 (499) in Patients with FSGS
Session Information
- Glomerular Clinical Trials: From Data to Impact
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Young, David, Processa Pharmaceuticals Inc, Hanover, Maryland, United States
- Bigora, Sian E, Processa Pharmaceuticals Inc, Hanover, Maryland, United States
- Das, Maya, Heliconia West LLC, Santa Monica, California, United States
- Madden, Yvonne A, Processa Pharmaceuticals Inc, Hanover, Maryland, United States
Background
Introduction: The challenges to obtaining approval for rare primary glomerular diseases (PGDs) have been the acceptable FDA endpoint, the pathophysiological complexity of PGD, and the time/cost of the Phase 2-3 program. The FDA has dealt with the endpoint challenge by accepting a surrogate endpoint of albuminuria/proteinuria for PGDs. Processa (PCSA) is addressing the other challenges as it develops 499, a broad-spectrum activity drug ideal for the complexity of FSGS.
499 Background: Pentoxifylline (PTX) (FDA approved but not for PGD) has 7 active metabolites including its major metabolite, the S isomer of lisophylline (S-M1). 499 is the deuterated form of S-M1. Although 499 is metabolized to PTX and the same metabolites as PTX and S-M1, the amount and formation rate of the metabolites are quantitatively different, resulting in different exposure and activity for 499 and its metabolites compared to dosing PTX or S-M1.
The effects of PTX and 499 have been evaluated in patients with CKD. PTX significantly decreased proteinuria in diabetic nephropathy (DN) patients after administration of 0.8–1.2 gm/d compared to patients on placebo, but side effects were significant with 23% of the patients withdrawing. In a small study of membranous glomerulonephritis patients treated with PTX or placebo, patients on PTX had significantly reduced mean proteinuria along with a slight, non-significant increase of eGFR, in comparison to placebo. 499 at 1.2 gm/d has only been evaluated in 2 CKD studies including DN, resulting in stable and slightly lower urine albumin-creatinine ratios compared to placebo with minimal side effects.
Methods
Thought Process in Evaluating Phase 2-3 Programs
Questions Phase 2-3 program must address for FDA approval:
● How safe is 499 in FSGS patients?
● What patient inclusion/exclusion criteria should be targeted for treatment?
● What dosage regimen provides an approvable safety-efficacy profile?
Results
Phase 2-3 programs evaluated:
● Phase 2 study followed by a standard Phase 3 study with an interim analysis to evaluate sample size re-estimation
● Seamless Phase 2/3 study with interim analysis to evaluate safety, drop (or add) a dose, and/or sample size re-estimation
Conclusion
PCSA will share different Phase 2-3 programs that may improve the efficiency of clinically evaluating 499 in FSGS.