Keryx Biopharma Issues Update from Ongoing Zerenex LT Safety Extension Study

Keryx Biopharmaceuticals, Inc.

today 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. 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. This 48-week, open-label extension (OLE) study, which is not a regulatory requirement, is being conducted in 35 sites in the United States. The study commenced enrollment in August 2012 and is anticipated to be completed in the first half of 2014.    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.  Enrollment in the OLE study included 168 patients, of which 166 patients were dosed with Zerenex, consisting of 114 and 52 patients from the Zerenex and Active Control arms of the completed long-term Phase 3 study, respectively.     The data presented is through October 31, 2013, and appear to corroborate the data observed in the completed long-term Phase 3 study. Key highlights from this preliminary data include: o Effective control of serum phosphorus within the normal range of 3.5 to 5.5 mg/dL; o Increase and plateau of transferrin saturation (TSAT) and ferritin at weeks 12 and 24, respectively, with ferritins decreasing after week 36; o Extremely limited use of intravenous (IV) iron in the study, with 69% of patients not receiving any IV iron throughout the study; and o Substantially lower use of IV iron and erythropoiesis stimulating agents (ESAs) in the OLE study, as compared to national averages, by 85% and 62%, respectively, while maintaining hemoglobin.  Mean Laboratory Measurements:               Baseline Week 12 Week 24 Week 36 Week 48 Number of subjects at timepoint as of October 31,  166  154  135  108  59 2013 Serum phosphorus (mg/dL)  5.7  5.3  5.3  5.2  5.5 TSAT (%) 32 38 36 38 38 Ferritin (ng/mL) 700 804 848 846 717 Note: Missing values were not imputed. IV Iron Use in the OLE Study: Based on these preliminary data through October 31, 2013, the observed uses of IV iron and ESAs in the OLE study are substantially lower than the national averages, as referenced in the most recent U.S. Dialysis Outcomes and Practice Patterns (DOPPS) database, as of April 2013.  Per the OLE protocol, the use of IV iron is prohibited if the patient's ferritin is > 500 ng/mL or TSAT is > 30%. The use of IV iron in this study has been extremely limited to date, with 69% of the OLE patients receiving no IV iron at all in the study.  Moreover, as of October 31, the mean monthly administered IV iron dose per patient, for all treated patients in the OLE, is only 32mg/month, or 380mg/year (median dose = 0), compared to the national mean monthly administered IV iron dose per the current DOPPS report of approximately 210 mg/month, or 2500mg/year. This represents an 85% reduction in IV use as compared to the current national average, thereby supporting the Company's belief that treatment with Zerenex could substantially eliminate the need for IV iron in the overwhelming majority of patients on Zerenex. ESA Use in the OLE Study: There are no study protocol limitations on the use of ESAs in the OLE study and ESAs are administered at the physician's discretion. To date, the weekly average administered dose of ESAs per patient, for all treated patients in the OLE, is 4,500 units/week, compared to the national mean weekly administered ESA dose per the current DOPPS report of 11,800 units/week, representing a reduction of 62% compared to the national average. Also of interest, the current DOPPS report also provides the national median weekly administered ESA dose of 6,800 units/week per patient. In the OLE study to date, the median weekly administered ESA dose is 2,200 units/week per patient, representing a reduction of 68% compared to the national median weekly dose.   Moreover, the preliminary data suggests that hemoglobin appears stable throughout the study, with the baseline hemoglobin level at 11.1 g/dL, and subsequent measurements between 11.1 and 11.6 g/dL (11.5 g/dL at week 48). These 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. Safety and Tolerability: To date, Zerenex appears to be safe and well-tolerated in the study. Importantly, there are no clinically meaningful changes in serum calcium levels and liver enzymes as measured by alanine transaminase (ALT) and aspartate transaminase (AST). The discontinuation rate in the study, to date, is approximately 17%. Ron Bentsur, the Company's Chief Executive Officer, commented, "While preliminary, I believe that the data from this OLE study to date reinforces the data observed in the long-term Phase 3 study. Importantly, it is encouraging to see that Zerenex appears to be safe and well tolerated for up to two years of cumulative exposure in clinical studies." Mr. Bentsur continued, "Also of note is the extremely limited use of IV iron and the considerably lower use of ESAs observed in the OLE study to date, as compared to the national averages, while maintaining stable hemoglobin levels. With approximately $2.5 billion of annual spending on ESAs and IV iron in the U.S. dialysis setting, the OLE study could further highlight the potential profound pharmaco-economic benefits that we believe Zerenex can bring forth in dialysis." The Company's New Drug Application (NDA) 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. Keryx holds a worldwide license (except for certain Asian Pacific countries) to Zerenex (ferric citrate coordination complex) from Panion & BF Biotech, Inc. The Japanese rights are sublicensed by Keryx to Japan Tobacco Inc. and Torii Pharmaceutical Co., Ltd.