Human Genome Sciences and GlaxoSmithKline Announce Positive Results in Second of Two Phase 3 Trials of Benlysta™ in Lupus

ROCKVILLE, Maryland, and LONDON, UK – November 2, 2009 – Human Genome Sciences, Inc. (Nasdaq: HGSI) and GlaxoSmithKline PLC (GSK) today announced that BENLYSTA™ (belimumab) met the primary endpoint in BLISS-76, the second of two pivotal Phase 3 trials in seropositive patients with systemic lupus erythematosus (SLE).  BLISS-76 study results through 52 weeks showed that belimumab 10 mg/kg plus standard of care achieved a statistically significant improvement in patient response rate as measured by the SLE Responder Index at Week 52, compared with placebo plus standard of care.  Study results also showed that belimumab was generally well tolerated, as demonstrated by a similar rate of discontinuations due to adverse events across treatment groups, with overall adverse event rates comparable between belimumab and placebo treatment groups.