Physiologically-Based Pharmacokinetic Model of Sparsentan to Evaluate Drug-Drug Interaction Potential
Clinical Pharmacology and Therapeutics Pharmacometrics & Systems Pharmacology – 2023
The Dual Endothelin A and Angiotension II Type 1 Receptor Antagonist Sparsentan (FILSPARI®) Exhibits a Safe Nonclinical Male Fertility Toxicity Profile
Journal article
Published on December 30, 2024
Contributors:
Bedard PW, Pretto F, Patel S et al.
Bedard PW, Pretto F, Patel S et al.
DOI:
10.1016/j.yrtph.2024.105770
10.1016/j.yrtph.2024.105770
Summary
Nonclinical (animal) studies show sparsentan is not toxic to the testes or the spermatogenic process
Background
Sparsentan is a novel, first-in-class, single-molecule, Dual Endothelin Angiotensin Receptor Antagonist (DEARA) and a highly selective antagonist for both the endothelin type A receptor (ETAR) and angiotensin II subtype 1 receptor (AT1R).
Because sparsentan is unique in antagonizing both ETAR and AT1R, it cannot be assumed to share the risks of molecules that belong solely to either endothelin receptor antagonists (ERA) or angiotensin II type 1 receptor blockers (ARB). To date, the effects of sparsentan on nonclinical male fertility have not been reported.
Nonclinical toxicity and fertility studies with ERAs have reported testicular tubular atrophy and were associated with some occurrence of hypospermia or aspermia. In contrast, toxicity studies with ARBs were not directly associated with toxicity to the testes or the spermatogenic process.
Aim
This set of nonclinical studies describe the fertility profile of sparsentan in animal models and explores whether the profile is similar to that of marketed ERAs or ARBs.
Approach
Toxicology studies were conducted on mice, rats, and monkeys. These included repeat dose toxicity studies that evaluated up to 3 months in mice, 6 months in rats, and 9 months in monkeys, and a carcinogenicity study in rats that evaluated up to 2 years. Varying doses of sparsentan were administered daily via oral syringe.
Observations specific to male fertility in the repeat dose toxicology studies included:
- Histopathological and microscopic analyses, and macroscopic observations of the testes or other male reproductive tissues
- Sperm concentration and motility evaluations with computer-assisted sperm analysis
General and reproductive toxicity evaluations were conducted on both male and female rats and measured:
- Clinical signs
- Premature deliveries
- Mortality
- Body weight
- Food consumption
- Estrous cycling
- Reproductive organ weights
- Gross necropsy of males and females
- Intra- and postpartum evaluations
Findings
Studies related to male fertility
Repeat dose toxicity studies showed no macroscopic or microscopic changes in the testes or other male reproductive tissue in mice, rats, or monkeys for exposures well above the clinical exposures of 400- and 800-mg doses of sparsentan.
Fertility studies did not demonstrate effects on reproductive performance or early embryonic development in males and females at exposures beyond the maximum human recommended dose (MHRD).
In juvenile toxicity studies, neither histologic changes to the testes nor effects on sperm parameters (motility, concentration, and morphology) were seen with sparsentan. Additionally, no effects were observed on sexual maturation in males or females, estrous cyclicity, or mating and fertility indices during the treatment or recovery periods.
Studies not directly related to male fertility
Toxicological findings included:
- Dose-related reversible increases in liver weight with or without increases in serum hepatic enzymes (alanine aminotransferase, aspartate aminotransferase, or γ-glutamyltransferase) and hepatocellular hypertrophy in mice and rats only
- No carcinogenic findings in male or female mice or rats treated with sparsentan
Unlike clinically approved ERAs, sparsentan did not cause any toxicologic effects on spermatogenesis, functional sperm parameters, or any other effects in the testes in animal studies.
Significant FSGS-related work productivity impairment1
- Adults with FSGS reported 26.7% overall work impairment and 37.8% activity impairment due to FSGS
- Care-partners of adult patients and caregivers of pediatric patients reported 15.0% and 30.6% overall work impairment due to FSGS-related reasons, respectively
Key takeaway
Nonclinical studies have shown that sparsentan is not toxic to the testes or the spermatogenic process and displays a profile more like ARBs than ERAs in the male fertility toxicity profile.
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Footnotes
This study was funded by Travere Therapeutics, Inc. Please see the publication for the full list of disclosures.
ARB, angiotensin II type 1 receptor blocker; AT1R, angiotensin II subtype 1 receptor; DEARA, Dual Endothelin Angiotensin Receptor Antagonist; ERA, endothelin receptor antagonist; ETAR, endothelin type A receptor; MHRD, maximum human recommended dose.
Bedard PW et al. Regul Toxicol Pharmacol. 2025;156:105770.
MA-SP-25-0090 | November 2025