Human Genome Sciences and GlaxoSmithKline Announce Positive Phase 3 Study Results for BENLYSTA(TM) in Systemic Lupus Erythematosus

- BENLYSTA (belimumab) met its primary efficacy endpoint by achieving a
    statistically significant improvement in patient response rate versus
    placebo in BLISS-52 -

    - First drug for lupus to reach this advanced stage of clinical
development
    and achieve positive results, in the largest randomized placebo-controlled
    clinical trial ever completed in SLE patients -ROCKVILLE, Maryland and LONDON, July 20 /CNW/ -- Human Genome Sciences,
Inc. (Nasdaq: HGSI) and GlaxoSmithKline PLC (GSK) today announced that
BENLYSTA(TM) (belimumab, formerly LymphoStat-B ) met the primary endpoint in
BLISS-52, the first of two pivotal Phase 3 trials in patients with
serologically active systemic lupus erythematosus (SLE).  In the
placebo-controlled BLISS-52 study, the results showed that belimumab plus
standard of care achieved a clinically and statistically significant
improvement in patient response rate at Week 52, compared with standard of
care alone.  Study results also showed that belimumab was generally well
tolerated, with adverse event rates comparable between belimumab and placebo
treatment groups.(Logo: http://www.newscom.com/cgi-bin/prnh/20080416/HGSLOGO)"The BLISS-52 results demonstrated that BENLYSTA has the potential to
become the first new approved drug in decades for people living with systemic
lupus," said H. Thomas Watkins, President and Chief Executive Officer, HGS. 
"Given the limited treatment options currently available, patients would
benefit greatly from potential new treatments.  BENLYSTA is an outstanding
example of the type of treatment HGS is working to develop and bring to
patients.  Assuming positive results in November from our second Phase 3 trial
of BENLYSTA, we and GSK plan to submit marketing applications in the United
States, Europe and other regions in the first half of 2010."

    Belimumab is an investigational drug and the first in a new class of
drugs called BLyS-specific inhibitors.  No new drug for lupus has been
approved by regulatory authorities in more than 50 years.  Belimumab is being
developed by HGS and GSK under a co-development and commercialization
agreement entered into in August 2006.

    "Lupus is a chronic, often debilitating, and sometimes fatal illness that
affects an estimated five million people worldwide and can have a devastating
effect on both patients living with the disease and their families," said
Carlo Russo, M.D., Senior Vice President, Biopharm Development, GSK. 
"BENLYSTA is the first medicine being developed specifically for lupus that
has reached this late stage of clinical development with positive results.  We
look forward to completing the pivotal studies, with the hope of bringing this
potentially important therapeutic advance to patients suffering from SLE."Key Findings from BLISS-52"The BLISS-52 results support and extend the findings that emerged in the
serologically active subgroup of SLE patients at Week 52 in our Phase 2
trial," said David C. Stump, M.D., Executive Vice President, Research and
Development, HGS.  "We are delighted to report that the efficacy of treatment
with BENLYSTA plus standard of care was superior in this study to that of
placebo plus standard of care, while the safety profile was comparable overall
to placebo.  BENLYSTA met the primary endpoint in this Phase 3 study at a
robust level of statistical significance.  BENLYSTA also significantly reduced
SLE disease activity versus placebo based on a number of other measures,
including SELENA SLEDAI and Physician's Global Assessment.  Of note, a greater
percentage of patients receiving BENLYSTA achieved a clinically meaningful
reduction in steroid dose.  We hope to have a full presentation of BLISS-52
results at an appropriate scientific meeting later in 2009."Topline BLISS-52 results include:
     -- Based on an intention-to-treat (ITT) analysis, belimumab met its
         primary efficacy endpoint of superiority versus placebo at Week 52.
         A clinically and statistically significant improvement was shown in
         patient response rate for belimumab plus standard of care, vs.
         placebo plus standard of care:  57.6% for 10 mg/kg belimumab, 51.7%
         for 1 mg/kg belimumab, and 43.6% for placebo (p=0.0006 and p=0.011
         for 10 mg/kg and 1 mg/kg belimumab, respectively vs. placebo).
         Patient response was defined by an improvement in SELENA SLEDAI
         score of 4 points or greater, no clinically significant BILAG
         worsening, and no clinically significant worsening in Physician's
         Global Assessment.Results for each individual component of the patient response rate
        were consistent with the overall improvement shown for the primary
        endpoint.-- Results for prespecified major secondary efficacy endpoints were:
          -- A significantly greater percentage of patients receiving
              belimumab achieved a reduction in SELENA SLEDAI score of at
              least 4 points by Week 52, with 58.3% for 10 mg/kg belimumab,
              53.% for 1 mg/kg belimumab, and 46.0% for placebo (p=0.0024 and
              p=0.019 for 10 mg/kg and 1 mg/kg belimumab, respectively vs.
              placebo).
          -- Improvement in Physician's Global Assessment (PGA) at Week 24
              was greatest in the belimumab 10 mg/kg treatment group versus
              placebo (p=0.0003 for 10 mg/kg and p=0.27 for 1 mg/kg belimumab,
              respectively) with improvement observed within 4-8 weeks.
          -- A higher percentage of patients in both belimumab treatment
              groups, versus placebo, had their average prednisone dose
              reduced by at least 25% from baseline to 7.5 mg per day or less
              during the last 12 weeks of study (p=0.053 for 10 mg/kg and
              p=0.025 for 1 mg/kg belimumab, respectively vs. placebo).
          -- Improvement in health-related quality of life at Week 24 as
              measured by the SF-36 Physical Component Summary (PCS) score was
              not significantly different among treatment groups.  However,
              although not a major secondary endpoint, improvement in the
              SF-36 PCS score at Week 52 was significantly greater in both
              belimumab treatment groups (p=0.025 for 10 mg/kg and p=0.027 for
              1 mg/kg belimumab, respectively vs. placebo).-- In BLISS-52, belimumab was generally well tolerated, with rates of
         overall adverse events, serious adverse events, infections and
         fatalities comparable between belimumab and placebo treatment groups.
         Serious infections were reported in 5.9% of patients on placebo and
         6.1% of patients on belimumab.  The most common adverse events were
         headache, arthralgia, upper respiratory tract infections, urinary
         tract infection and influenza, and were also comparable between
         belimumab and placebo treatment groups.  No malignancies were
         reported.Professor Sandra V. Navarra, M.D., a principal investigator and Head of
Rheumatology at the University of Santo Tomas, Manila, The Philippines, said,
"Given the limitations of available therapies, there is a great need for well
tolerated and effective treatments for lupus.  We are very encouraged by the
findings of BLISS-52, and look forward to presenting these results later in
the year.  We also look forward to the results of BLISS-76 later this year."About the BENLYSTA (belimumab) Phase 3 Development ProgramThe Phase 3 development program for belimumab includes two double-blind,
placebo-controlled, multi-center Phase 3 superiority trials - BLISS-52 and
BLISS-76 - to evaluate the efficacy and safety of belimumab plus standard of
care, versus placebo plus standard of care, in serologically active (i.e.,
autoantibody-positive) patients with SLE. This is the largest clinical trial
program ever conducted in lupus patients.  BLISS-52 randomized and treated 865
patients at 90 clinical sites in 13 countries, primarily in Asia, South
America and Eastern Europe.  BLISS-76 enrolled and randomized 826 patients at
133 clinical sites in 19 countries, primarily in North America and Europe. 
The design of the two trials is similar, but the duration of therapy in the
two studies is different - 52 weeks for BLISS-52 and 76 weeks for BLISS-76.
The data from BLISS-76 will be analyzed after 52 weeks in support of a
potential Biologics License Application in the United States and Marketing
Authorization Application in Europe and other regions. HGS designed the Phase
3 program for belimumab in collaboration with GSK and leading international
SLE experts, and the program is being conducted under a Special Protocol
Assessment agreement with FDA.

    The primary efficacy endpoint of BLISS-52 and BLISS-76 is the patient
response rate at Week 52, as defined by: (1) a reduction from baseline of at
least 4 points on the SELENA SLEDAI disease activity scale (which indicates a
clinically important reduction in SLE disease activity); (2) no worsening of
disease as measured by the Physician's Global Assessment (worsening defined as
an increase of 0.30 points or more from baseline); and (3) no new BILAG A
organ domain score (which indicates a severe flare of lupus disease activity)
and no more than one new BILAG B organ domain score (which would indicate a
moderate flare of disease activity).  Analysis for the primary endpoint is
based on intention-to-treat (ITT) and adjusted for baseline stratification
factors, including SELENA SLEDAI score, proteinuria and race.

    In each of the two Phase 3 trials, patients were randomized to one of
three treatment groups: 10 mg/kg belimumab (BLISS-52, n=290), 1 mg/kg
belimumab (BLISS-52, n=288), or placebo (BLISS-52, n=287). Patients are dosed
intravenously on Days 0, 14 and 28, then every 28 days thereafter for the
duration of the study. All receive standard of care therapy in addition to the
study medication. Safety is reviewed by an independent Data Monitoring
Committee throughout both studies.About BENLYSTA (belimumab)Belimumab is an investigational human monoclonal antibody drug that
specifically recognizes and inhibits the biological activity of B-lymphocyte
stimulator, or BLyS . BLyS is a naturally occurring protein discovered by HGS
that is required for the development of B-lymphocyte cells into mature plasma
B cells. Plasma B cells produce antibodies, the body's first line of defense
against infection.  In lupus and certain other autoimmune diseases, elevated
levels of BLyS are believed to contribute to the production of autoantibodies
- antibodies that attack and destroy the body's own healthy tissues. The
presence of autoantibodies appears to correlate with disease severity.
Preclinical and clinical studies suggest that belimumab can reduce
autoantibody levels in SLE.  BLISS 52 results suggest that belimumab can
reduce SLE disease activity, and a second Phase 3 trial, BLISS-76, is underway
to confirm these results.About the Collaboration with GSKIn August 2006, HGS and GSK entered into a definitive co-development and
co-commercialization agreement under which HGS has responsibility for
conducting the belimumab Phase 3 trials, with assistance from GSK. The
companies will share equally in Phase 3/4 development costs, sales and
marketing expenses, and profits of any product commercialized under the
current agreement.About Systemic Lupus ErythematosusSystemic lupus erythematosus (SLE) is a chronic, life-threatening
autoimmune disease. Approximately five million people worldwide, including
approximately 1.5 million in the United States, suffer from various forms of
lupus, including SLE. Lupus can occur at any age, but appears mostly in young
people ages 15 to 45. About 90 percent of those diagnosed with lupus are
women. African-American women are about three times more likely to develop
lupus, and it is also more common in Hispanic, Asian and American Indian
women. Symptoms may include extreme fatigue, painful and swollen joints,
unexplained fever, skin rash and kidney problems. Lupus can lead to arthritis,
kidney failure, heart and lung inflammation, central nervous system
abnormalities, inflammation of the blood vessels and blood disorders. For more
information on lupus, visit the Lupus Foundation of America at www.lupus.org,
the Lupus Research Institute at www.lupusresearchinstitute.org, the National
Institute of Arthritis and Musculoskeletal and Skin Diseases at
www.niams.nih.gov, or Lupus Europe at www.elef.rheumanet.org.Conference CallHGS management will hold a conference call to discuss this announcement
today at 8:15 AM Eastern.  Investors may listen to the call by dialing
888-632-5010 or 913-312-0402, passcode 8364417, five to 10 minutes before the
start of the call. A replay of the conference call will be available within a
few hours after the call ends. Investors may listen to the replay by dialing
888-203-1112 or 719-457-0820, confirmation code 8364417.  Today's conference
call also will be webcast and can be accessed at www.hgsi.com. Investors
interested in listening to the live webcast should log on before the
conference call begins to download any software required. Both the audio
replay and the archive of the conference call webcast will remain available
for several days.About GlaxoSmithKlineGlaxoSmithKline is one of the world's leading research-based
pharmaceutical and healthcare companies, and is committed to improving the
quality of human life by enabling people to do more, feel better and live
longer.  For more information, visit GlaxoSmithKline on the World Wide Web at
www.gsk.com.About Human Genome SciencesThe mission of HGS is to apply great science and great medicine to bring
innovative drugs to patients with unmet medical needs. The HGS clinical
development pipeline includes novel drugs to treat hepatitis C, lupus,
inhalation anthrax and cancer.

    The Company's primary focus is rapid progress toward the
commercialization of its two lead drugs, Albuferon  (albinterferon alfa-2b)
for hepatitis C and BENLYSTA(TM) (belimumab, formerly LymphoStat-B ) for
lupus. Albuferon has now completed Phase 3 development, and the submission of
global marketing applications is expected in fall 2009.  BENLYSTA successfully
met its primary endpoint in the first of two Phase 3 trials in systemic lupus
erythematosus; results of the second BENLYSTA Phase 3 trial are expected in
November 2009.  Also in late-stage development is raxibacumab (ABthrax(TM))
for the treatment of inhalation anthrax (Biologics License Application
currently pending with the U.S. Food and Drug Administration).  In addition,
HGS has substantial financial rights to certain products in the GSK clinical
pipeline including darapladib, currently in Phase 3 development in patients
with coronary heart disease, and Syncria  (albiglutide), currently in Phase 3
development in patients with type 2 diabetes.

    For more information about HGS, please visit the Company's web site at
www.hgsi.com.  Health professionals and patients interested in clinical trials
of HGS products may inquire via e-mail to [e-mail] or by
calling HGS at [phone], extension 3550.   HGS, Human Genome Sciences,
ABthrax, Albuferon, BENLYSTA, BLyS and LymphoStat-B are trademarks of Human
Genome Sciences, Inc.HGS Safe Harbor StatementThis announcement contains forward-looking statements within the meaning
of Section 27A of the Securities Act of 1933, as amended, and Section 21E of
the Securities Exchange Act of 1934, as amended. The forward-looking
statements are based on Human Genome Sciences' current intent, belief and
expectations. These statements are not guarantees of future performance and
are subject to certain risks and uncertainties that are difficult to predict.
Actual results may differ materially from these forward-looking statements
because of the Company's unproven business model, its dependence on new
technologies, the uncertainty and timing of clinical trials, the Company's
ability to develop and commercialize products, its dependence on collaborators
for services and revenue, its substantial indebtedness and lease obligations,
its changing requirements and costs associated with facilities, intense
competition, the uncertainty of patent and intellectual property protection,
the Company's dependence on key management and key suppliers, the uncertainty
of regulation of products, the impact of future alliances or transactions and
other risks described in the Company's filings with the Securities and
Exchange Commission. In addition, while the Company has completed delivery of
ABthrax to the U.S. Strategic National Stockpile, the Company will continue to
face risks related to FDA's approval of the Company's Biologics License
Application for ABthrax. If the Company is unable to meet requirements
associated with the ABthrax contract, future revenues from the sale of ABthrax
to the U.S. Government will not occur. Existing and prospective investors are
cautioned not to place undue reliance on these forward-looking statements,
which speak only as of today's date. Human Genome Sciences undertakes no
obligation to update or revise the information contained in this announcement
whether as a result of new information, future events or circumstances or
otherwise.GlaxoSmithKline Forward-Looking StatementsUnder the safe harbor provisions of the US Private Securities Litigation
Reform Act of 1995, GSK cautions investors that any forward-looking statements
or projections made by GSK, including those made in this announcement, are
subject to risks and uncertainties that may cause actual results to differ
materially from those projected.  Factors that may affect GSK's operations are
described under 'Risk Factors' in the 'Business Review' in GSK's Annual Report
on Form 20-F for 2008.

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Corporate Communications, [phone], Investors: Peter Vozzo, Senior
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