Not so fast: FDA tacks 3 more months onto decision date for Calliditas' rare kidney disorder drug
It looks like the FDA’s decision on Calliditas’ IgA nephropathy candidate Nefecon is going to take a few months longer than expected — allowing time for rivals like Martin Shkreli’s former company Travere Therapeutics to catch up.
Five months after granting Nefecon priority review, the FDA is extending its PDUFA date from Sept. 15 to Dec. 15, Calliditas announced on Tuesday. The Swiss biotech filed for accelerated approval back in March, based on data from 200 patients in the first part of the Phase III NefIgArd trial who showed a significant reduction in proteinuria, or excessive protein in the urine.
IgAN is a rare condition that damages the filters, or glomeruli, inside the kidneys, causing the organs to lose their function. This is the first time regulators are considering an approval on the basis of proteinuria as a surrogate endpoint for accelerated approval in IgAN, according to Calliditas. High levels of proteinuria are considered an early sign of kidney function decline.
Upon reviewing the NDA, regulators requested further analyses, including additional information on estimated glomerular filtration rate (eGFR), as further support of Calliditas’ proteinuria data, the company said in a statement. The changes were classified as major amendments to the NDA.
“We will continue to cooperate closely with the FDA as they complete the review of our NDA,” CEO Renée Aguiar-Lucander said in the statement.
If approved, Nefecon could become the first approved treatment in the US for the rare kidney disorder. But competitors like Travere’s sparsentan and Chinook Therapeutics’ atrasentan aren’t far behind.
Last month, Travere (formerly Retrophin) said that IgAN patients who took sparsentan in a pivotal trial saw a mean reduction in proteinuria of 49.8% from baseline at 36 weeks. That compares to a mean reduction of 15.1% in a group of patients who took Avapro, a current standard of care (p<0.0001).
While it’s difficult to compare trials, it appears as though sparsentan may have the upper hand in proteinuria reduction. In November, Calliditas said Nefecon-treated patients from the first part of the NefIgArd trial had a 31% reduction in proteinuria after nine months, compared to a 5% reduction in those on placebo (p=0.005).
Chinook is currently in a Phase III trial with atrasentan, an endothelin receptor antagonist the company licensed from AbbVie for an undisclosed price back in 2019. AbbVie had previously been developing atrasentan for diabetic kidney disease, but shut down a Phase III trial in 2017 when monitoring of renal events “revealed considerably fewer end-points than expected by this time.”
SVB Leerink’s Joseph Schwartz said the FDA’s decision to extend Nefecon’s PDUFA date is “not entirely shocking given the recent increased regulatory scrutiny at the FDA.”
“While some investors may view this announcement as a negative for TVTX and KDNY, as both companies are pursuing similar strategies for accelerated approval in IgAN, we note that Nefecon is a steroid which has a distinct mechanism from both TVTX’s sparsentan and KDNY’s atrasentan,” he wrote to investors on Tuesday.