Keryx Biopharmaceuticals, a biopharmaceutical company based in New York, N.Y., has initiated a phase II study of Zerenex (ferric citrate), the company's ferric iron-based phosphate binder drug candidate, in managing serum phosphorus and iron deficiency in anemic patients with Stage 3 to 5 non-dialysis dependent chronic kidney disease (NDD-CKD).

The multicenter, randomized, safety and efficacy study will enroll approximately 150 patients from approximately 15 sites in the U.S. Patients will receive with either Zerenex or placebo for a 12-week treatment period. The primary endpoints of the study are to demonstrate changes in ferritin, TSAT and serum phosphorus levels over the 12-week treatment period. Secondary endpoints include changes in hemoglobin and FGF-23.  Patient enrollment is expected to take up to 6 months, with study completion expected in mid-2013.

Zerenex is currently also in a long-term phase III study, under Special Protocol Assessment, as treatment for end-stage renal disease patients with hyperphosphatemia on dialysis. Top-line data from this study is expected to be announced by approximately year-end 2012, with the NDA filing expected in the first quarter of 2013 for this indication.

Keryx Biopharmaceuticals retains a worldwide exclusive license (except for the Asian Pacific Region) to Zerenex from Panion & BF Biotech.