New York, NY -- (SBWIRE) -- 01/29/2013 -- Keryx Biopharmaceuticals, Inc. (NASDAQ: KERX) announced successful top-line results from the long-term Phase 3 study of Zerenex™ (ferric citrate), the Company's ferric iron-based phosphate binder drug candidate, for the treatment of elevated serum phosphorus levels, or hyperphosphatemia, in patients with end-stage renal disease (ESRD) on dialysis.