Keryx Biopharmaceuticals Provides Update From Ongoing Zerenex(TM) (ferric citrate coordination complex) Long-Term Safety

Keryx Biopharmaceuticals Provides Update From Ongoing Zerenex(TM) (ferric
citrate coordination complex) Long-Term Safety Extension Study in Patients
With Hyperphosphatemia on Dialysis

Data to Date Support Results From Long-Term Phase 3 Study

NEW YORK, Nov. 8, 2013 (GLOBE NEWSWIRE) -- Keryx Biopharmaceuticals, Inc.
(Nasdaq:KERX) 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:

  oEffective control of serum phosphorus within the normal range of 3.5 to
    5.5 mg/dL;
  oIncrease and plateau of transferrin saturation (TSAT) and ferritin at
    weeks 12 and 24, respectively, with ferritins decreasing after week 36;
  oExtremely limited use of intravenous (IV) iron in the study, with 69% of
    patients not receiving any IV iron throughout the study; and
  oSubstantially 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.

About Keryx Biopharmaceuticals, Inc.

Keryx Biopharmaceuticals is focused on the acquisition, development and
commercialization of medically important pharmaceutical products for the
treatment of renal disease. Keryx is developing Zerenex (ferric citrate
coordination complex), an oral, ferric iron-based compound that has the
capacity to bind to phosphate and form non-absorbable complexes. Keryx has
completed a U.S.-based Phase 3 clinical program for Zerenex for the treatment
of hyperphosphatemia (elevated phosphate levels) in patients with chronic
kidney disease on dialysis, conducted pursuant to a Special Protocol
Assessment (SPA) agreement with the Food and Drug Administration (FDA).The
Company's New Drug Application (NDA) is currently under review by the FDA with
an assigned Prescription Drug User Fee Act (PDUFA) goal date of June 7,
2014.The Marketing Authorization Application filing with the European
Medicines Agency (EMA) is pending submission.The Company is also developing
Zerenex in the U.S. for the management of elevated phosphorus and iron
deficiency anemia in patients with Stages 3 to 5 non-dialysis dependent
chronic kidney disease. In addition, Keryx's Japanese partner, Japan Tobacco
Inc. and Torii Pharmaceutical Co., Ltd. has filed its New Drug Application for
marketing approval of ferric citrate in Japan for the treatment of
hyperphosphatemia in patients with chronic kidney disease. Keryx is
headquartered in New York City.

Forward-Looking Statements

Some of the statements included in this press release, particularly those
relating to the results of clinical trials, the clinical benefits to be
derived from Zerenex (ferric citrate coordination complex), regulatory
submissions and the timing of any such review, approvals, the commercial
opportunity and competitive positioning, and any 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: safety and efficacy data from
the ongoing 48-week, open-label extension (OLE) study presented herein are
preliminary and unaudited in nature and there is the risk that the data and
our interpretation of the data and its findings and conclusions could change
following a more comprehensive review of the data or upon the completion of
the study; acceptance of the NDA filing represents only a preliminary
evaluation of the application and is not indicative of deficiencies that may
be identified during the FDA's review; a PDUFA goal date is subject to change
and does not guarantee that the review of the NDA will be completed on a
timely basis; the risk that the FDA, EMA, and/or the Japanese Ministry of
Health, Labour and Welfare ultimately deny approval of the U.S. NDA, MAA
and/or Japanese NDA, respectively; the risk that SPAs are not a guarantee that
the FDA will ultimately approve a product candidate following filing
acceptance; whether the FDA and EMA will concur with our interpretation of our
Phase 3 study results, supportive data, or the conduct of the studies;
whether, Zerenex, if approved, will be successfully launched and marketed; 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 is not incorporated by reference into this press release
and is included for reference purposes only.

CONTACT: KERYX CONTACT:
         Lauren Fischer
         Director - Investor Relations
         Keryx Biopharmaceuticals, Inc.
         Tel: 212.531.5965
         E-mail: lfischer@keryx.com

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