Keryx Biopharma Reports Preliminary Data From Safety Extension Study Of Zerenex

(RTTNews) - Keryx Biopharmaceuticals, Inc. (KERX) announced preliminary, unaudited data from an ongoing 48-week safety extension study of Zerenex (ferric citrate coordination complex), the company's drug candidate for the treatment of hyperphosphatemia in patients with chronic kidney disease on dialysis. The study commenced enrollment in August 2012 and is anticipated to be completed in the first half of 2014. The company said the data presented is through October 31, 2013, and appear to corroborate the data observed in the completed long-term Phase 3 study.

Only patients who had participated in, and successfully completed the 58-week, long-term Phase 3 study were eligible for enrollment into this safety extension study. Patients in the OLE study are titrated to achieve and maintain normal serum phosphorus levels (3.5 to 5.5 mg/dL) for a period of 48 weeks. This study, together with the 58-week, long-term Phase 3 safety and efficacy study, represents potential cumulative exposure to Zerenex of up to 2 years.

Key highlights from the preliminary data include: effective control of serum phosphorus within the normal range of 3.5 to 5.5 mg/dL; increase and plateau of transferrin saturation and ferritin at weeks 12 and 24, respectively, with ferritins decreasing after week 36; extremely limited use of intravenous (IV) iron in the study, with 69% of patients not receiving any IV iron throughout the study; and substantially lower use of IV iron and erythropoiesis stimulating agents in the OLE study, as compared to national averages, by 85% and 62%, respectively, while maintaining hemoglobin.

The company said, to date, Zerenex appears to be safe and well-tolerated in the study. There are no clinically meaningful changes in serum calcium levels and liver enzymes as measured by alanine transaminase and aspartate transaminase. The discontinuation rate in the study, to date, is approximately 17%.

The preliminary data suggests that hemoglobin appears stable throughout the study. The preliminary data on IV iron and ESA use in the OLE study appear to corroborate the long-term Phase 3 data by demonstrating Zerenex's ability to significantly reduce the need for IV iron and ESAs, while maintaining hemoglobin in dialysis patients.

The company's New Drug Application for the use of Zerenex for the treatment of hyperphosphatemia in chronic kidney disease patients on dialysis is currently under review by the FDA with an assigned Prescription Drug User Fee Act (PDUFA) goal date of June 7, 2014.