ROCKVILLE, Maryland – October 13, 2004 – Human Genome Sciences, Inc. (Nasdaq: HGSI) announced today that it has begun dosing patients in a Phase 2 clinical trial of HGS-ETR1 (agonistic human monoclonal antibody to TRAIL Receptor 1) in patients with advanced non-Hodgkin’s lymphoma.

The Phase 2 clinical trial is a multi-center, open-label study to evaluate the efficacy, safety and tolerability of HGS-ETR1 in patients with relapsed or refractory non-Hodgkin’s lymphoma. The Phase 2 study will enroll a maximum of thirty patients. Each patient will receive up to six cycles of treatment in the absence of disease progression, with HGS-ETR1 administered as an intravenous infusion once every twenty-one days. The objectives of the study are to evaluate disease activity and tumor response to HGS-ETR1 in patients with advanced non-Hodgkin’s lymphoma, to evaluate the safety and tolerability of HGS-ETR1, and to determine plasma concentrations of HGS-ETR1 for use in a population pharmacokinetic analysis. Disease response will be assessed using the International Working Group Recommendations for Non-Hodgkin’s Lymphoma, which were established in 1999 to provide an objective means for evaluating changing disease status and the efficacy of drugs in the treatment of non-Hodgkin’s lymphoma.¹

In a separate press release distributed earlier today, Human Genome Sciences announced that it has begin dosing patients in a Phase 2 clinical trial of HGS-ETR1 in patients with advanced colorectal cancer.² On September 8, 2004, the company announced the initiation of a Phase 2 study of HGS-ETR1 in patients with advanced non-small cell lung cancer.³ The three Phase 2 studies of HGS-ETR1 initiated to date fit into a global clinical development program through which Human Genome Sciences plans to evaluate the novel, genomics-derived anticancer drug’s potential for use in the treatment of specific cancers.

Anas Younes, M.D., Professor, Lymphoma/Myeloma, University of Texas M.D. Anderson Cancer Center, Houston, said, “Non-Hodgkin’s lymphoma is the seventh most common cancer in the United States, with approximately 56,000 new cases diagnosed each year. 4 The current standard of care calls for treating most patients with a combination of chemotherapy and, in recent years, monoclonal antibodies. This therapeutic approach produces cures in approximately fifty percent of patients with aggressive lymphoma. Those who relapse or do not respond are treated with additional chemotherapeutic and other therapeutic modalities, but cures are difficult to achieve. New therapies that can improve response rates, extend the duration of response, extend survival, minimize toxicity, and provide patients with improved quality of life represent a significant need. We look forward to evaluating HGS-ETR1 to determine whether it may play a role in the treatment of non-Hodgkin’s lymphoma.” ^5-13

David C. Stump, M.D., Executive Vice President, Drug Development, said, “The interim results from our ongoing Phase 1 clinical trials of HGS-ETR1 demonstrate that it is well tolerated and can be safely and repetitively administered to patients with non-Hodgkin’s lymphoma or advanced solid tumors.^14-19 Based on the clinical evidence to date, along with strong preclinical support, we are pleased to initiate a Phase 2 study of HGS-ETR1 in patients with non-Hodgkin’s lymphoma. We look forward to continuing to elucidate the potential of HGS-ETR1 as a treatment for solid tumor and other malignancies.”

Craig A. Rosen, Ph.D., President and Chief Operating Officer, said, “The advancement of HGS-ETR1 to Phase 2 clinical trials is one of the key milestones that we set for Human Genome Sciences at the beginning of 2004. We are now moving forward with a broad Phase 2 program of clinical study to investigate the use of HGS-ETR1 in the treatment of specific cancers, including colorectal cancer, non-small cell lung cancer, and non-Hodgkin’s lymphoma. The results of our own in vitro and in vivo preclinical studies, as well as studies conducted by others, demonstrate that agonistic antibodies to TRAIL Receptors 1 and 2 have significant potential to provide novel therapeutic options to patients with a variety of cancer types, including non-Hodgkin’s lymphoma. ^20-45 Our preclinical studies also show that the activity of HGS-ETR1 may be increased by co-treatment with chemotherapeutic agents.”^46-52

Interim results of two ongoing Phase 1 multi-center, open-label, dose-escalation clinical trials of HGS-ETR1 were presented in September 2004 at the 16^th EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapeutics in Geneva, Switzerland. ^14-16 The data presented demonstrate the safety and tolerability of HGS-ETR1 in patients with advanced solid tumors or non-Hodgkin’s lymphoma, and support further evaluation of HGS-ETR1 in Phase 2 clinical trials, both as a single agent and in combination with chemotherapy. Data were presented on thirty-nine patients treated to date in a Phase 1 study conducted in patients with advanced solid tumors.^{14, 16} Interim results of the ongoing study demonstrate that HGS-ETR1 can be administered safely and repetitively to patients with advanced solid malignancies at doses up to and including 10 mg/kg intravenously every 28 days. No evidence of drug-related hematologic or hepatic toxicity has been observed at the doses administered to date. The Maximum Tolerated Dose (MTD) has not been reached, and accrual in the trial continues at a dose of 10 mg/kg every 14 days. Some preliminary evidence of biological activity has been observed. Durable stable disease for greater than eight months was observed in one patient with metastatic sarcoma. Durable stable disease was observed for four months in one patient with head-and-neck cancer and in one patient with Ewing’s sarcoma; both patients continue on treatment. Data also were presented on twenty-four patients treated to date in an additional Phase 1 study conducted in patients with advanced solid tumors or non-Hodgkin’s lymphoma. Results presented from the ongoing clinical trial demonstrate that HGS-ETR1 is well tolerated with no clearly attributable toxicities to date and that the MTD has not been reached. Stable disease has been observed in eight patients for greater than two cycles. The trial continues to enroll patients.^15-16

Human Genome Sciences, using genomic techniques, originally identified the TRAIL Receptor-1 protein as a member of the tumor necrosis factor receptor super-family. The company’s own studies, as well as those conducted by others, show that TRAIL Receptor 1 plays a key role in triggering apoptosis, or programmed cell death, in tumors. Human Genome Sciences took the approach of developing human monoclonal antibodies that would bind the receptor and stimulate the TRAIL Receptor-1 protein to trigger apoptosis in cancer cells, in much the same way that the native TRAIL ligand (tumor necrosis factor-related apoptosis-inducing ligand) triggers it, but with the advantage of a longer half-life and an exclusive specificity for TRAIL Receptor 1. The TRAIL Receptor 1 agonistic human monoclonal antibody, HGS-ETR1, was made in a collaboration between Human Genome Sciences and Cambridge Antibody Technology.⁵³ The drug will be produced in the Human Genome Sciences clinical manufacturing facilities located in Rockville, Maryland. Human Genome Sciences holds the commercial rights to the drug.

For more information about HGS-ETR1, see www.hgsi.com/products/ETR1.html. Health professionals interested in more information about trials involving HGSI products are encouraged to inquire via the Contact Us section of the Human Genome Sciences web site, www.hgsi.com/products/request.html, or by calling (301) 610-5790, extension 3550.

Human Genome Sciences is a company with the mission to treat and cure disease by bringing new gene-based protein and antibody drugs to patients.

HGS and Human Genome Sciences 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.

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Footnotes:

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CONTACTS:
David C. Stump, M.D.
Executive Vice President, Drug Development
240/314-4400
Jerry Parrott
Vice President, Corporate Communications
301/315-2777
Kate de Santis
Director, Investor Relations
301/251-6003