The Food and Drug Administration (FDA) has granted orphan drug designation for Retrophin’s sparsentan for the treatment of focal segmental glomerulosclerosis (FSGS). Currently, there are no approved therapies for FSGS in the United States.

FSGS is a rare and severe nephropathy that is a leading cause of end-stage renal disease. Sparsentan is a investigational drug that acts as both a selective endothelin receptor antagonist and an angiotensin receptor blocker. Some studies of similar nephropathies have demonstrated endothelin receptor antagonists and angiotensin receptor blockers to be effective in reducing proteinuria.

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The Company has begun the Phase 2 DUET Trial of sparsentan for the treatment of FSGS (n=100). This randomized study includes a 8-week double-blind treatment followed by a 40-week open-label treatment.

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