Keryx Biopharmaceuticals Initiates Phase 3 Registration Program of Zerenex (ferric citrate) for the Treatment of Patients with Hyperphosphatemia

NEW YORK, May 6 /PRNewswire-FirstCall/ -- Keryx Biopharmaceuticals, Inc. (Nasdaq: KERX) announced today the initiation of its short-term Phase 3 study of Zerenex™ (ferric citrate), the Company's iron-based phosphate binder for the treatment of elevated serum phosphorous levels, or hyperphosphatemia, in patients with end-stage renal disease on dialysis.  The initiation of this study marks the commencement of the Company's Phase 3 registration program for Zerenex, which is being conducted in accordance with a Special Protocol Assessment (SPA) agreement with the FDA.  Pursuant to the Company's SPA agreement, the Zerenex Phase 3 registration program will consist of the short-term efficacy study initiated today, and 58-week long-term safety and efficacy study, to be initiated in the third quarter of 2010.  Patients completing the short term study are eligible to be enrolled into the long-term study.

The short-term efficacy study initiated today is a multicenter, randomized, open-label clinical trial with a planned enrollment of approximately 150 patients on hemodialysis.  All patients will undergo a 2-week washout period, following which the patients will be randomized 1:1:1 to receive a fixed dose of Zerenex (1 gram, 6 grams or 8 grams per day) for a treatment period of 28 days.  The primary endpoint of the study is to demonstrate a dose response in the change of serum phosphorous from baseline (end of washout period) to end of the treatment period (day 28). Approximately 15 sites in the U.S. will participate in the study.  Patient enrollment is expected to take up to 6 months, with study completion expected by the end of 2010.

Dr. Julia Lewis, Professor of Medicine, Department of Nephrology, Vanderbilt University School of Medicine, and member of the Executive Committee of the Collaborative Study Group, will be the Study Chair of the Zerenex Phase 3 registration program.  Dr. Samuel S. Blumenthal, Professor of Medicine at Medical College of Wisconsin, will serve as the study's Co-Principal Investigator.

Dr. Julia Lewis commented, "I am pleased to be leading the registration program for Zerenex.  The clinical data generated to date suggests that Zerenex is an effective, safe and well-tolerated phosphate binder which we expect is differentiated from other marketed therapies by its iron composition and potential dosing convenience.  We are hopeful that this Phase 3 registration program of Zerenex will lead to a new treatment option for hyperphosphatemia benefiting patients with end-stage renal disease."

Ron Bentsur, Chief Executive Officer of Keryx , commented, "We are very excited about the initiation of the Zerenex Phase 3 program and look forward to generating Phase 3 data from this study later this year."  Mr. Bentsur, continued, "We believe that Zerenex could emerge with the attributes to capture meaningful market share in a worldwide phosphate binder market approaching $1.5 billion.  Finally, I want to thank the study investigators for their tremendous support and guidance."

Keryx expects to complete the Zerenex Phase 3 program and file a New Drug Application for Zerenex for the treatment of hyperphosphatemia in the first half of 2012.

Keryx Biopharmaceuticals retains a worldwide exclusive license (except for the Asian Pacific Region) to Zerenex (ferric citrate) from Panion & BF Biotech, Inc.  The Company has sublicensed the development of ferric citrate in Japan to Japan Tobacco Inc. and Torii Pharmaceutical Co., Ltd.

PHASE 3 TRIAL DESIGN:

In accordance with the Company's SPA agreement with the FDA, the Phase 3 clinical program for Zerenex will consist of two clinical studies, as follows:

Short-term efficacy study: A multicenter, randomized, open-label clinical trial with a planned enrollment of approximately 150 patients on hemodialysis, who will be randomized to fixed doses of Zerenex, ranging from 1 gram per day to 8 grams per day, for a treatment period of 28 days. Patients will undergo a 2-week washout period prior to randomization.  The primary endpoint of the study will be to demonstrate a dose response in the change of serum phosphorous from baseline (end of washout period) to end of the treatment period (day 28).

Long-term safety and efficacy study: A multicenter, randomized, open-label, safety and efficacy clinical trial with a planned enrollment of approximately 300 patients on hemodialysis or peritoneal dialysis.  The long term study will consist of a 2-week washout period followed by a 52-week safety assessment in which patients will be randomized 2:1 to receive either Zerenex or another phosphate binder.  The 52-week safety assessment will be followed by a 4-week efficacy assessment in which only patients randomized to treatment with Zerenex during the safety assessment will be randomized to continue treatment with either Zerenex or placebo for a 4-week period.

About Special Protocol Assessments

The Special Protocol Assessment (SPA) process is a procedure by which the FDA provides official evaluation and written guidance on the design and size of proposed protocols that are intended to form the basis for a new drug application.

Final marketing approval depends on the results of efficacy, the adverse event profile and an evaluation of the benefit/risk of treatment demonstrated in the Phase 3 clinical program.  The SPA agreement may only be changed through a written agreement between the sponsor and the FDA, or if the FDA becomes aware of a substantial scientific issue essential to product efficacy or safety.  For more information on Special Protocol Assessment, please visit: http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/ucm080571.pdf.

About Hyperphosphatemia

In the United States, according to data from the U.S. Renal Data System, there are approximately 485,000 patients with end-stage renal disease, or ESRD, and the number of ESRD patients is projected to rise 60% to approximately 785,000 by 2020. The majority of ESRD patients, close to 400,000, require dialysis. Phosphate retention and the resulting hyperphosphatemia in patients with ESRD on dialysis are usually associated with secondary hyperparathyroidism (and its related cardiovascular complications), renal osteodystrophy and soft tissue mineralization. ESRD patients usually require treatment with phosphate-binding agents to lower and maintain serum phosphorus at acceptable levels. The need for alternative phosphate-binding agents has long been recognized, especially given the increasing prevalence of ESRD as well as shortcomings with current therapies. Zerenex has the potential to be an effective and safe treatment in lowering and/or maintaining normal serum phosphorus levels in patients with ESRD and hyperphosphatemia.

The market for phosphate binders to treat hyperphosphatemia in ESRD patients in 2009 was approximately $750 million and $1.3 billion in the U.S. and worldwide, respectively.

About Keryx Biopharmaceuticals, Inc.

Keryx Biopharmaceuticals is focused on the acquisition, development and commercialization of medically important pharmaceutical products for the treatment of life-threatening diseases, including cancer and renal disease. Keryx is developing KRX-0401 (perifosine), a novel, potentially first-in-class, oral anti-cancer agent that inhibits Akt activation in the phosphoinositide 3-kinase (PI3K) pathway, and also affects a number of other key signal transduction pathways, including the JNK pathway, all of which are pathways associated with programmed cell death, cell growth, cell differentiation and cell survival. KRX-0401 has demonstrated both safety and clinical efficacy in several tumor types, both as a single agent and in combination with novel therapies. KRX-0401 is currently in Phase 3 clinical development for both refractory advanced colorectal cancer and multiple myeloma, and in Phase 1 and 2 clinical development for several other tumor types. Each of the KRX-0401 Phase 3 programs are being conducted under Special Protocol Assessment (SPA) agreements with the FDA. Keryx is also developing Zerenex(TM) (ferric citrate), an oral, iron-based compound that has the capacity to bind to phosphate and form non-absorbable complexes. The Phase 3 clinical program of Zerenex in the treatment for hyperphosphatemia (elevated phosphate levels) in patients with end-stage renal disease is being conducted pursuant to an SPA agreement with the FDA. Keryx is headquartered in New York City.

Cautionary Statement

Some of the statements included in this press release, particularly those anticipating future clinical trials and business prospects for Zerenex™ may be forward-looking statements that involve a number of risks and uncertainties. For those statements, we claim the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995. Among the factors that could cause our actual results to differ materially are the following: our ability to successfully and cost-effectively complete clinical trials for Zerenex™; the risk that the data (both safety and efficacy) from the Phase 3 trials will not coincide with the data analyses from the Phase 2 clinical trials previously reported by the Company; and other risk factors identified from time to time in our reports filed with the Securities and Exchange Commission. Any forward-looking statements set forth in this press release speak only as of the date of this press release. We do not undertake to update any of these forward-looking statements to reflect events or circumstances that occur after the date hereof. This press release and prior releases are available at http://www.keryx.com. The information found on our website and the FDA website is not incorporated by reference into this press release and is included for reference purposes only.

SOURCE Keryx Biopharmaceuticals, Inc.