Retrophin ($RTRX) and partner Ligand Pharmaceuticals ($LGND) were both up on top-line Phase II data for sparsentan to treat focal segmental glomerulosclerosis (FSGS), a rare kidney disorder that can be a precursor to end-stage renal disease. The drug already had orphan drug designation in this indication in both the U.S. and the EU.
In early trading on the news, Retrophin was up by roughly one-third to a market cap of about $800 million while Ligand rose about 8% to hit a valuation of more than $2.4 billlion.
Controversial former Retrophin CEO Martin Shkreli immediately stepped in to claim a bit of credit, boasting on Twitter that sparsentan was the first drug he ever did research on. Shkreli was ousted from Retrophin in 2014 and later sued by the company, which alleged that he used company funds for personal reasons and to keep his investment firm afloat.
The Phase II data hit the primary endpoint of a greater than twofold reduction in proteinuria compared to irbesartan. This was after the 8-week, double-blind treatment period. Proteinuria is a protein found in the urine; reduction in it is expected to be beneficial in the treatment of FSGS and could reduce the risk of progression to end-stage renal disease.
Currently, these patients are managed with angiotensin receptor blockers, angiotensin converting enzyme inhibitors, calcineurin inhibitors, and steroids.
“Sparsentan is one of Ligand’s top partnered portfolio assets, and we are very pleased to see this asset progress,” said Ligand CEO John Higgins in a statement. Retrophin in-licensed rights to sparsentan under a 2012 deal with Ligand in which it paid a $1 million upfront and committed to more than $75 million in milestone payments, as well as 9% royalties on future worldwide sales.
Known as DUET, the study found that mean reduction of proteinuria in 64 patient from baseline was 44.8% on three different doses of sparsentan. The mean reduction for the irbesartan 32-patient arm was 18.5%.
The reduction for the two highest doses of sparsentan was a bit better at 47.4% than the overall mean.
"The results from DUET serve as proof of concept for sparsentan's novel approach of combining endothelin receptor type A blockade with angiotensin II inhibition for the treatment of FSGS," said Retrophin EVP and head of R&D Dr. Alvin Shih.
Retrophin investors as of the end of June included Perceptive Advisors (8.9%), Consonance Capital management (7.4%), Broadfin Capital (7.3%), Jennison Associates (6.2%) and Fidelity Management Research (5.5%).