- Shares in Travere Therapeutics, a biotechnology company founded a decade ago by Martin Shkreli, sank by 30% Tuesday after the company disclosed a drug it’s developing for a leading cause of kidney failure failed in a late-stage clinical trial.
- Summary results from the study showed Travere’s drug, called sparsentan, did not improve kidney function by significantly more than an existing medicine after two years of treatment. Sparsentan’s safety profile was similar to the comparator drug, Travere said.
- News of the study failure comes nearly three months after Travere won Food and Drug Administration approval of sparsentan for treatment of another disease that affects the kidneys, IgA nephropathy. Travere had hoped to use the most recent study to expand sparsentan’s use to include the kidney disorder focal segmental glomerulosclerosis, or FSGS.
While sparsentan missed the trial’s main goal, Travere highlighted the drug’s strong effect on urine protein levels, which is seen as an indirect marker of kidney health. In FSGS, progressive scarring of the kidney disrupts the organ’s normal filtration capacity, allowing protein to leak into the urine — a symptom known as proteinuria that is thought to further exacerbate the disease.
In the study, treatment with sparsentan led to an average reduction in proteinuria by 50% from patients’ baseline, compared to 32% for those given the control drug irbesartan. (The drug’s effect on this marker of disease at a previous interim analysis had led Travere to push on with the study.)
But on the trial’s main goal assessing changes in kidney filtration capacity, sparsentan treatment did not result in a decline from baseline that was statistically greater than what was reported for irbesartan. Still, Travere plans to dig into the data further and discuss it with regulators.
“We are disappointed that we did not achieve the primary efficacy endpoint in this study, but we did see results that trended favorably for sparsentan that we are further exploring to determine a potential path forward in FSGS,” said Eric Dube, Travere’s CEO, in the company’s statement.
To Maury Raycroft, an analyst at Jefferies, those discussions are worth having, even if the chances of using the data to support an approval are slim.
"Based on the minimal amount of details in the top-line data, we do not see an obvious path [forward] as it stands,” wrote Raycroft in a client note. “However, it makes sense for the co[mpany] to fully analyze the data and have conversations w[ith] regulators on possible next step paths since there is nothing approved for FSGS.”
Both Raycroft and Joseph Schwartz, an analyst with SVB Securities, see limited impact from the study results on sparsentan’s use in IgA nephropathy, where Travere sells it as Filspari.
“The trial miss further highlights that IgAN and FSGS are truly distinct conditions ... despite both being glomerular diseases, the latter of which is much more heterogeneous, with relapsing/remitting disease, which likely also played a role in the trial miss,” Schwartz wrote in a client note.
Still, Travere’s approval for Filspari was conditional and based on changes in proteinuria. An ongoing Phase 3 trial is testing Filspari against irbesartan to confirm whether the drug improves kidney function in IgA nephropathy.
Both conditions are rare, although FSGS is less common in the U.S. Along with Travere, Vertex Pharmaceuticals is also developing a treatment for the condition, but only in people with a certain genetic mutations.
Travere has been developing sparsentan since 2012, when it was known as Retrophin and run by Shkreli. After Shkreli’s arrest and imprisonment for securities fraud, Retrophin changed its name to Travere and has worked to distance itself from its founder.