Human Genome Sciences Phase 2 Clinical Trial of HGS-ETR1 in Combination With Bortezomib

First clinical study of HGS-ETR1 in combination with another therapeutic agent for the treatment of a hematopoietic cancer

Human Genome Sciences, Inc. (Nasdaq: HGSI - News) announced today that it has initiated dosing of patients in a randomized Phase 2 clinical trial of HGS-ETR1 (mapatumumab) in combination with bortezomib (VELCADE®) in advanced multiple myeloma.

"Clinical and preclinical evidence continues to emerge suggesting that agonistic antibodies to TRAIL receptors 1 and 2 have significant potential to provide novel therapeutic options to patients with multiple myeloma and a variety of other cancer types."

"The results of preclinical studies demonstrate that HGS-ETR1 enhances the tumor-killing activity of bortezomib. These data, along with emerging clinical results, support the evaluation of HGS-ETR1 in combination with bortezomib in a Phase 2 study in patients with relapsed or recurrent multiple myeloma. We look forward to determining whether this combination has the potential to play a role in the treatment of multiple myeloma."

About the Phase 2 Trial Design

The primary objective of the study is to evaluate disease response to HGS- ETR1 in combination with bortezomib, versus bortezomib alone, in patients with relapsed or refractory multiple myeloma. The Phase 2 trial is a randomized, multi-center, open-label study to evaluate the efficacy and safety of HGS-ETR1 in combination with bortezomib in patients with relapsed or refractory multiple myeloma. Approximately 100 patients will be enrolled in the United States and Canada and randomized into two treatment groups, with one treatment group receiving the combination of HGS-ETR1 and bortezomib, and the other treatment group receiving bortezomib alone. Secondary objectives are to evaluate safety and tolerability, and to determine plasma concentrations of HGS-ETR1 for use in a population pharmacokinetic analysis.

About Phase 2 Results to Date

HGS has completed three Phase 2 clinical trials of HGS-ETR1 to evaluate its potential as a single agent for the treatment of specific cancers, including non-Hodgkin's lymphoma, non-small lung cancer, and colorectal cancer.

The results of a Phase 2 clinical trial in patients with non-Hodgkin's lymphoma (NHL) demonstrated that HGS-ETR1 was well tolerated, showed signs of clinical activity in patients with relapsed or refractory NHL, and could be administered safely and repetitively. Of the patients enrolled, 43% (17/40) were diagnosed as having follicular lymphomas. Clinical responses (1 complete response and 2 partial responses) were observed in 3/17 (18%) patients with follicular lymphomas, and 11/17 (65%) of these patients exhibited either response or stable disease. Clinical and preclinical results to date suggest that further clinical evaluation of HGS-ETR1 in combination with other therapeutic agents is warranted in patients with lymphomas and hematologic malignancies.

The results of separate Phase 2 clinical trials of HGS-ETR1 as a single agent in advanced non-small cell lung cancer (NSCLC) and advanced colorectal cancer (CRC) showed that the HGS-ETR1 was well tolerated and could be administered safely and repetitively. Stable disease was observed in approximately 29% of patients participating in the NSCLC study, and in approximately 32% of the patients participating in the CRC study. The results of these studies, along with the interim results of two ongoing Phase 1b trials support further evaluation of HGS-ETR1 in combination with chemotherapeutic agents.

About HGS-ETR1

HGS-ETR1 is an agonistic human monoclonal antibody that specifically binds to the TRAIL receptor-1 protein and triggers programmed cell death, or apoptosis, in cancer cells. HGS-ETR1 does this by mimicking the activity of the natural protein TRAIL (tumor necrosis factor apoptosis-inducing ligand). Human Genome Sciences' own studies, as well as those of others, show that TRAIL receptor 1 is expressed on a number of solid tumors and tumors of hematopoietic origin. It has been demonstrated that cell lines derived from a broad array of solid and hematologic human tumors, including lung, colon, breast, multiple myeloma, prostate, pancreas, and lymphoid, are sensitive to killing by apoptosis induced by either native TRAIL or agonistic antibodies to TRAIL receptors 1 and 2.

HGS-ETR1 was generated through a collaboration between HGS and Cambridge Antibody Technology. GlaxoSmithKline (GSK) has exercised its option under a June 1996 agreement to develop and commercialize HGS-ETR1 jointly with HGS. Under the terms of the agreement, GSK and HGS will share equally in Phase 3/4 development costs, and will share equally in sales and marketing expenses and profits of any commercialized product, under a co-development and co-promotion agreement, the remaining terms of which are being negotiated by the parties.

About Human Genome Sciences

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

The HGS clinical development pipeline includes drugs to treat hepatitis C, lupus, anthrax disease, cancer, rheumatoid arthritis and HIV/AIDS. The Company's primary focus is rapid progress toward the commercialization of its two lead compounds, Albuferon(TM) for hepatitis C, and LymphoStat-B(TM) for lupus. Both compounds are expected to advance to Phase 3 clinical trials in 2006.

In June 2006, HGS announced that the U.S. Government has exercised its option under an existing contract to purchase 20,000 doses of ABthrax(TM), for the treatment of anthrax disease. Other HGS compounds in clinical development include three TRAIL receptor antibodies for the treatment of hematopoietic and solid malignancies, in addition to an antibody to the CCR5 receptor for the treatment of HIV/AIDS.

For more information about Human Genome Sciences, please visit the Company's web site at www.hgsi.com. For more information about HGS-ETR1, see www.hgsi.com/products/ETR1.html.

ABthrax, Albuferon, LymphoStat-B, HGS and Human Genome Sciences are trademarks of Human Genome Sciences, Inc.

Safe Harbor Statement

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.

Source: Human Genome Sciences, Inc.