Sparsentan Cuts Proteinuria 70% in New IgAN: Chee Kay Cheung, MBChB

Starting sparsentan early in patients with newly diagnosed IgA nephropathy (IgAN) reduced proteinuria by about 70% and kept kidney function fairly stable over 2 years in the SPARTAN (NCT01946204) study. Chee Kay Cheung, MBChB, PhD, consultant nephrologist and honorary associate professor at University Hospitals of Leicester NHS Trust, discussed the results presented at the American Society of Nephrology’s Kidney Week and what they may mean for first-line treatment in an interview with The American Journal of Managed Care^®.

How the SPARTAN Study Isolated Sparsentan’s Effects

Cheung said SPARTAN was set up as a mechanistic study to examine the effects of sparsentan in newly diagnosed patients with IgAN. Participants had undergone a biopsy within 6 months of study entry and had not taken a renin-angiotensin system inhibitor, an angiotensin-converting enzyme inhibitor, or an angiotensin receptor blocker in the 12 months before enrolling. The goal was to see the drug’s effects on its own in this population.

Proteinuria fell by about 70% within the first 36 weeks, according to Cheung, and kidney function remained fairly stable over the 2-year period. Among the 12 patients in the study, the decline in estimated glomerular filtration rate was close to what is seen with normal aging, as noted during the interview.

Cheung urged caution in interpreting the findings. The study was small and open label, and it focused specifically on newly diagnosed patients. Even so, Cheung said the data suggest a benefit to earlier treatment.

“If we can start these treatments earlier in the disease course, then hopefully we can better preserve kidney function over a longer term period,” said Cheung.

Why Proteinuria Remission Matters for First-Line Choice

Three-quarters of patients reached complete proteinuria remission at some point during SPARTAN. Cheung called proteinuria one of the most important modifiable biomarkers in IgAN because it shows how the kidney disease is responding to treatment.

Cheung said registry data support the importance of that target. “Achieving a low level of proteinuria to this degree is associated with a much better long-term outcome,” said Cheung.

Proteinuria is not the only factor clinicians should weigh, Cheung said. Kidney function decline, how well patients tolerate the medication, and safety also need to be considered. In his view, data from SPARTAN and from the phase 3 studies of sparsentan suggest a benefit in those areas as well.