Travere Therapeutics

Researchers are looking for a better way to treat people living with classical homocystinuria (HCU), a rare inherited condition. It is caused by changes in the cystathionine beta-synthase (or "CBS") gene and prevents an enzyme from working correctly in the body. This enzyme helps break down homocysteine, which is produced when the body processes methionine from protein-containing foods. This helps keep homocysteine and methionine at healthy levels. When this enzyme is not working, homocysteine and methionine build up in the blood and then spread into different tissues of the body and stop these body tissues from working normally. People living with HCU can experience problems with their vision, bones, blood vessels, thinking, learning, and memory. Available treatments for HCU include a low-methionine diet (typically achieved by limiting protein-containing foods), a methionine-free protein supplement to help meet daily protein needs, and betaine (Cystadane®). These treatments are either not sufficient or are hard to take for many patients. Pegtibatinase was designed by researchers to act like the CBS enzyme, which is missing or not working properly in people living with HCU. Researchers are studying whether adding pegtibatinase to standard treatment can lower homocysteine levels. Researchers want to learn how safe and effective pegtibatinase is, how it moves through and affects the body, and how it may affect the daily lives of people with HCU. The study plans to enroll participants from the US, Australia, Belgium, France, Germany, Ireland, Italy, Poland, Portugal, Qatar, Saudi Arabia, Spain, Turkey, and the United Kingdom. Many study visits may happen at home, depending on where you live and local regulations. Some visits may include a home nurse and telemedicine appointments with the study doctor.Show more

Researchers are looking for a better way to treat people who have classical homocystinuria (HCU), a rare condition that is passed down by parents (or "genetic condition"). It is caused by changes in the cystathionine beta-synthase (or "CBS") gene and prevents an enzyme from working correctly in the body. This enzyme breaks down a substance called homocysteine (from dietary methionine found in protein) and keeps both homocysteine and methionine at normal levels. When this enzyme is not working, homocysteine and methionine build up in the blood, which spreads into different tissues of the body and stops these body tissues from working normally. People with HCU can experience problems with vision, bones, blood vessels, and cognitive function (the ability to think, learn, and remember). Treatments available for HCU, such as a low protein diet and betaine (Cystadane®), help reduce homocysteine levels. The diet is a low methionine diet and a methionine-free protein supplement (a product that provides extra protein to help meet daily protein needs). These treatments are either not sufficient or are hard to take for many patients. Pegtibatinase was developed by scientists to be a version of the CBS enzyme that can be given to people with HCU. Researchers believe that giving pegtibatinase to people with HCU already getting medical treatment (or "standard of care") may reduce their homocysteine levels. This study is split into 7 different groups getting different amounts of drug. The first 6 groups have already finished the study. Group 7 plans to enroll participants from the US (virtual and in-person), France, and Qatar.Show more

To determine the nephroprotective potential of treatment with sparsentan in (1: Cohort A) patients newly-diagnosed with immunoglobulin A nephropathy (IgAN) (ie, incident patients) who have not received prior angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) therapy, and in (2: Cohort B) patients with recurrent IgAN following kidney transplantation.Show more

To evaluate the safety, efficacy and tolerability of sparsentan oral suspension and tablets, and assess changes in proteinuria after once-daily dosing over 108 weeks.

To evaluate the safety and efficacy of sparsentan tablets for the treatment of patients with proteinuria after kidney transplantation with once-daily dosing for 36 weeks.

Two, both for rare kidney conditions.

Filspari (sparsentan): a once-daily pill that blocks 2 of the signals that damage the kidney's filters. Approved for IgA nephropathy (full approval September 2024) and, since April 13, 2026, for FSGS in adults and children 8 and older who do not have nephrotic syndrome, the first approved treatment for that disease.

Thiola EC (tiopronin): for cystinuria, a rare inherited cause of recurring kidney stones.

Sales: Filspari brought in $322 million of Travere's $410 million in 2025 product sales. In the first 9 months of 2026 it brought in $446.4 million of $506.0 million in US net product sales, including $200.2 million in the third quarter.

Source: Travere's FSGS approval release, April 13, 2026 and Travere's third quarter 2026 results, November 2, 2026.

Less protein leaking from the kidneys than with the drug doctors had been using off label, with no significant difference in how fast kidney function declined.

The trial: DUPLEX, a Phase 3 study that randomized 371 patients with FSGS to sparsentan or irbesartan, a blood pressure drug.

Protein leakage: at week 108 it fell 46% on sparsentan versus 30% on irbesartan across the whole trial, and 48% versus 27% in people without nephrotic syndrome, the group the approval covers.

Kidney function: no significant difference between the 2 drugs in the rate of decline over 108 weeks, which was the trial's main goal.

Source: the DUPLEX results in the New England Journal of Medicine, 2023, the Filspari FDA label, section 14 and our Filspari FSGS approval post.

An enzyme replacement therapy for classical homocystinuria, in a pivotal Phase 3 trial.

The disease: a rare metabolic disorder in which the body cannot process the amino acid homocysteine, leading to clots and eye and bone problems.

Status: FDA Breakthrough Therapy designation; the HARMONY trial restarted enrollment in early 2026 after a pause to scale up manufacturing, and Travere expects topline data in the second half of 2027.

Yes. Retrophin renamed itself Travere Therapeutics in November 2020.

Founded: 2011, as Retrophin.

Where: San Diego.

Ticker: TVTX on the Nasdaq. Older trial records and news still use the Retrophin name.

Yes, through Travere TotalCare.

Copay help: for people with commercial insurance.

Nurse educator: a dedicated contact, who also helps people with government insurance or no insurance.

Lab tests: the liver-monitoring blood tests required by Filspari's REMS program, done at home at no cost for eligible patients.

Links: the Filspari drug page links to the program, and our guide to appealing a rare disease drug denial uses Filspari as an example.

Travere Therapeutics has 1 FDA-approved drug with a rare disease use that we track, as of November 2026.

Filspari (sparsentan), approved 2023: IgA Nephropathy, Focal Segmental Glomerulosclerosis.

Source: the FDA's openFDA label database, matched to the rare diseases on Trial Friend; the list updates automatically and can include older products.

Yes, for 1 of its FDA-approved rare disease medicine that we track, each checked on Travere Therapeutics' own website.

Filspari: Travere TotalCare, 1-833-345-7727. Offers copay help with private insurance and insurance help. Checked October 26, 2026.

Medicare and Medicaid: drugmaker copay cards are limited to private insurance, so people with government coverage usually look to a free medicine program or a charity fund, both on the help paying page.

Eligibility is decided by each program, so call the number listed before a prescription is filled.