Calliditas Therapeutics AB’s (CALT) Nefecon is under priority review by the FDA, with a decision expected on September 15.Nefecon is a proprietary, novel oral formulation of budesonide, an established, local immunosuppressant, for the treatment of the autoimmune renal disease IgA nephropathy.IgA nephropathy, commonly known as Berger's disease, is a kidney disease caused by the build-up of an antibody called immunoglobulin A (IgA) in the kidneys.If approved, Nefecon would become the first therapy specifically designed and approved for the treatment of IgA nephropathy.Nefecon could achieve peak sales of $1 billion, according to analysts. CALT closed Friday’s trading at $23.91, up 0.46%.