Human Genome Sciences, Inc. Announces Positive Interim Results Of Phase 2b Clinical Trial Of Albuferon(TM) in Combination With Ribavirin In Treatment-Naive Patients With Chronic Hepatitis C

ROCKVILLE, Md., March 14 /PRNewswire-FirstCall/ -- Human Genome Sciences, Inc. today announced 12-week interim data from a Phase 2b clinical trial to evaluate the efficacy and safety of Albuferon(TM) (albumin-interferon alpha 2b) in combination with ribavirin in patients with genotype 1 chronic hepatitis C who are naive to interferon alpha-based treatment regimens.(1) The results to date demonstrate that Albuferon in combination with ribavirin was safe, well tolerated and showed robust antiviral activity. A presentation of the full interim data will take place on April 29 at the European Association for the Study of the Liver (EASL).(2)

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In a separate press release issued today, HGS reported the interim results of a Phase 2 clinical trial of Albuferon in combination with ribavirin in treatment-experienced patients with chronic hepatitis C.(3-4)

David C. Stump, M.D., Executive Vice President, Drug Development, said, "The interim results available to date from our Phase 2b trial are encouraging and supportive of our broadening program of clinical study of Albuferon.(1-12) We believe that an interferon with less frequent dosing than pegylated interferon, and with comparable safety and efficacy, would be an important therapeutic option for patients with chronic hepatitis C. Based on the 12-week virologic response data from the Phase 2b study, Albuferon appears capable of meeting this target at doses of 900-1200 mcg every 14 days. We are encouraged that the interim data at the 1200-mcg dose administered every two weeks show a trend for greater antiviral activity for Albuferon, compared with Pegasys administered every 7 days, with 75% of the patients in this group exhibiting a level of hepatitis C viral load below the level of quantitation, compared with 66% in the treatment group receiving 180 mcg of Pegasys at 7-day intervals. Response rates were somewhat lower at 12 weeks for the treatment group receiving 1200-mcg doses of Albuferon every 28 days, which suggests that higher doses will be required to optimize a 28-day dosing schedule. In other Phase 2 studies, we are evaluating Albuferon doses of 1500 mcg and 1800 mcg. Interim results show that these doses are well tolerated when given every 14 days and may have greater antiviral activity than the 900-mcg and 1200-mcg doses on the same schedule.(3-4)

"The 12-week data from the Phase 2b trial show that Albuferon in combination with ribavirin was well tolerated at all doses studied, with no discontinuations due to hematological abnormalities. The fewest dose reductions due to drops in hematologic cell counts were observed in the treatment group receiving 1200 mcg at 28-day intervals. These data support the continuing exploration of a treatment regimen that administers Albuferon at 28-day intervals with higher exposures than those investigated in the current trial. We look forward to presentation of the complete Phase 2b 12-week interim data set at the EASL meeting in April, and to continuing the evaluation of Albuferon in combination with ribavirin at higher doses and over the full term of the current study. Assuming that positive data continue to emerge from this Phase 2b study and our other ongoing Phase 2 trials of Albuferon, we plan to meet with clinical experts and regulatory authorities to discuss the initiation of Phase 3 development of Albuferon by year-end 2006."

The Phase 2b trial is a randomized, open-label, multi-center, active-controlled, dose-ranging study being conducted in Australia, Canada, Czech Republic, France, Germany, Israel, Poland and Romania.(1) A total of 458 patients with chronic hepatitis C genotype 1 have been enrolled and randomized into four treatment groups, three of which receive subcutaneously administered Albuferon (900 mcg at 14-day intervals, 1200 mcg at 14-day intervals, and 1200 mcg at 28-day intervals(13)). The fourth treatment group serves as the active control group and receives 180-mcg doses of subcutaneously administered peginterferon alfa-2a (Pegasys) at 7-day intervals. All patients receive weight-based oral daily ribavirin at 1000 or 1200 mg in two divided doses. The primary objectives of the Phase 2b study are to evaluate the efficacy and safety of Albuferon in combination with ribavirin, vs. Pegasys with ribavirin, in interferon alpha-naive patients with chronic hepatitis C genotype 1. The primary efficacy endpoint is sustained virologic response (SVR), defined as undetectable virus 24 weeks after completion of 48 weeks of treatment.

Virologic response and laboratory data are available on 458 patients through Week 12 of the Phase 2b trial. The data show the following percentages of patients with hepatitis C (HCV) RNA viral load below the level of quantitation (43 IU/mL) at Week 12: 66% (75/114) in the treatment group receiving 180-mcg doses of Pegasys at 7-day intervals; 75% (82/110) in the treatment group receiving 1200 mcg of Albuferon at 14-day intervals (p=0.15 vs. Pegasys); 69% (82/118) in the treatment group receiving 900 mcg of Albuferon at 14-day intervals (p=0.55 vs. Pegasys); and 53% (62/116) in the treatment group receiving 1200 mcg of Albuferon at 28-day intervals (p=0.056 vs. Pegasys). Data also are available on early virologic response at Week 12 (EVR12). (Early virologic response is defined as a reduction in HCV RNA viral load of at least 2 log -- 99% or greater.) The data show the following percentages of patients achieving EVR12: 89% (101/114) in the treatment group receiving 180-mcg doses of Pegasys at 7-day intervals; 90% (99/110) in the treatment group receiving 1200 mcg of Albuferon at 14-day intervals (p=0.73 vs. Pegasys); 84% (99/118) in the treatment group receiving 900 mcg of Albuferon at 14-day intervals (p=0.30 vs. Pegasys); and 76% (88/116) in the treatment group receiving 1200 mcg of Albuferon at 28-day intervals (p=0.011 vs. Pegasys).

Albuferon in combination with ribavirin was well tolerated. The incidence and duration of flu-like symptoms was similar in all groups, except for a higher rate of chills in the Albuferon groups. In general, the incidence and severity of other adverse events was similar across treatment groups, except for a higher rate of respiratory symptoms (primarily mild cough and dyspnea) in the Albuferon groups and a higher rate of psychiatric symptoms in the Pegasys group. Discontinuations due to adverse events were observed by treatment group as follows: 3 in the 180-mcg 7-day Pegasys cohort (n=114); 8 in the 1200-mcg 14-day Albuferon cohort (n=110); 3 in the 900-mcg 14-day Albuferon cohort (n=118); and 7 in the 1200-mcg 28-day Albuferon cohort (n=116). There were no discontinuations due to reductions in hematologic cell counts, which appeared to be maximal by Week 8, and were well managed with dose reductions in all treatment groups. The incidence of dose reduction due to hematologic abnormalities was similar in the Pegasys group and in Albuferon groups administered every 14 days, but occurred less frequently in the group administered 1200 mcg Albuferon every 28 days. The rate of emergent antibodies to interferon was significantly lower in the Albuferon treatment groups (3%) compared with the Pegasys treatment group (18%) through the first 12 weeks of treatment (p<0.0001).

HGS also announced that it has completed enrollment, randomization and initial dosing of 46 patients in a new Phase 2 clinical trial of Albuferon in combination with ribavirin in treatment-naive patients with genotype 2 or genotype 3 chronic hepatitis C. The Phase 2 trial is a randomized, open label, multi-center study being conducted in Canada. Participants have been randomized into two treatment cohorts, with all patients receiving 1500-mcg doses of Albuferon in combination with ribavirin for 24 weeks. Albuferon is administered every 14 days in one cohort and administered every 28 days in the other cohort. All patients receive oral daily ribavirin at 800 mg in two divided doses. The primary efficacy endpoint of the Phase 2 study is sustained virologic response (SVR), defined as undetectable hepatitis C virus (HCV) 24 weeks after completion of 24 weeks of treatment. Secondary endpoints include rapid virologic response (undetectable HCV RNA viral load) at Week 4, and safety and quality of life at Week 24.

Albuferon is a novel, long-acting form of interferon alpha 2b. It is a Human Genome Sciences drug made possible by the company's proprietary albumin fusion technology, which was used to improve the pharmacological properties of interferon alpha. Recombinant interferon alpha is approved for the treatment of hepatitis C, hepatitis B and a broad range of cancers. Human Genome Sciences is developing Albuferon for use in the treatment of chronic hepatitis C.

Hepatitis C is an inflammation of the liver caused by the hepatitis C virus. It is the most common chronic blood-borne infection in the developed world. It is estimated that as many as 170 million people worldwide are infected with hepatitis C virus. This includes nearly four million people in the United States. The hepatitis C virus is transmitted primarily through significant or repeated exposures to infected blood. Intravenous drug use and sexual contact with infected persons account for the majority of new hepatitis C infections. When detectable levels of the hepatitis C virus in the blood persist for at least six months, a person is diagnosed as having chronic hepatitis C.

CONFERENCE CALL

HGS management will hold a conference call to discuss this announcement today at 10:00 am Eastern Time. Investors may listen to the call by dialing 866/564-7439 or 719/785-9449, passcode 2094807, five to ten minutes before the start of the call. A replay of the conference call will be available for several days by dialing 888/203-1112 or 719/457-0820, passcode 2094807. This conference call also will be webcast. Interested parties who wish to listen to the webcast should visit the Human Genome Sciences Web site at http://www.hgsi.com . The archive of the conference call will be available several hours after the conference call and will remain available for several days.

Human Genome Sciences is a company with the mission to discover, develop, manufacture and market innovative drugs that serve patients with unmet medical needs, with a primary focus on protein and antibody drugs.

For more information about Albuferon, see http://www.hgsi.com/products/albuferon.html . Health professionals interested in more information about trials involving Human Genome Sciences products are encouraged to inquire via the Contact Us section of the company's Web site, http://www.hgsi.com/products/request.html , or by calling (301) 610-5790, extension 3550.

HGS, Human Genome Sciences and Albuferon are trademarks of Human Genome Sciences, Inc.

This 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 planned 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. 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.

Footnotes: 1. (HGSI Press Release) Human Genome Sciences Completes Patient Enrollment in a Phase 2b Clinical Trial of Albuferon in Combination with Ribavirin in Treatment-Naive Patients with Chronic Hepatitis C. October 25, 2005. 2. Zeuzem S, Benhamou Y, Shouval D, McHutchison J, Subramanian M, et al. Interim (week 12) Phase 2b virological efficacy and safety results of albumin interferon alfa-2b combined with ribavirin in genotype 1 chronic hepatitis C infection. 41st Annual Meeting of the European Association for the Study of the Liver (EASL), Vienna. Oral presentation #3088. 3. Rustgi V, Nelson D, Balan V, McHutchison J, Subramanian GM, et al. A Phase 2 dose-escalation study of Albuferon combined with ribavirin in non-responders to prior interferon based therapy for chronic hepatitis C infection. 41st Annual Meeting of the European Association for the Study of the Liver (EASL), Vienna. Oral presentation #113. 4. (HGSI Press Release) Human Genome Sciences Reports Positive Interim Results of Phase 2 Clinical Trial of Albuferon in Combination with Ribavirin in Treatment-Experienced Patients with Chronic Hepatitis C. March 14, 2006. 5. Nelson DR, et al. A Phase 2 study of Albuferon in combination with ribavirin in non-responders to prior interferon therapy for chronic hepatitis C. 56th Annual Meeting of the American Association for the Study of Liver Diseases (AASLD), 2005. Oral Presentation #204. 6. (HGSI Press Release) Human Genome Sciences Reports Interim Results of Phase 2 Clinical Trial of Albuferon in Combination with Ribavirin in Treatment-Experienced Hepatitis C Patients. November 15, 2005 7. Bain VG, Kaita KD, Yoshida EM, McHutchison JG, Subramanian GM, et al. A Phase 2 study to assess the antiviral activity, safety, and pharmacokinetics of recombinant human albumin-interferon alfa fusion protein in genotype 1 chronic hepatitis C patients. Journal of Hepatology (2006). 8. (HGSI Press Release) Human Genome Sciences Reports Positive Results of Phase 2 Clinical Trial of Albuferon in Treatment-Naive Patients with Chronic Hepatitis C. April 14, 2005. 9. Moore P, Balan V, et al. Modulation of interferon specific gene expression by Albuferon in subjects with chronic hepatitis C and correlation with anti-viral response. 40th Annual Meeting of the European Association for the Study of the Liver (EASL), Paris. April 14, 2005. Abstract #447. 10. Balan V, Nelson DR, Sulkowski MS, Subramanian GM, et al. A Phase I/II study evaluating escalating doses of recombinant human albumin- interferon-alfa fusion protein in chronic hepatitis C patients who have failed previous interferon-alfa-based therapy. Antiviral Therapy, 11:35-45. 11. (HGSI Press Release) Human Genome Sciences Reports Positive Results of Phase 1/2 Clinical Trial of Albuferon(TM) in Chronic Hepatitis C. November 2, 2004. 12. Balan V, et al. Molecular profiles of drug response in HCV infected patients during the first four weeks of therapy for chronic hepatitis C virus with pegylated interferon containing regimens or Albuferon. 54th Annual Meeting of the American Association for the Study of Liver Diseases, Boston. October 25, 2003. 13. It is important to note that the method of measurement for dose determination in the Phase 2b study of Albuferon in combination with ribavirin in treatment-naive patients (as well as in other Phase 2 studies of the compound) is different from the method of measurement in the Phase 1/2 study of Albuferon. Accordingly, the 900-mcg dose in the current study is equivalent to a 680-mcg dose in the Phase 1/2 study, and the 1200-mcg dose is equivalent to 900 mcg in the Phase 1/2 study.

Photo: NewsCom: http://www.newscom.com/cgi-bin/prnh/20010612/HGSLOGOPRN Photo Desk, photodesk@prnewswire.comHuman Genome Sciences, Inc.

CONTACT: Jerry Parrott, Vice President, Corporate Communications,+1-301-315-2777, Kate de Santis, Director, Investor Relations,+1-301-251-6003, both of Human Genome Sciences, Inc.

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