Harvard and Alexion researchers report successful transplantation of immuneprotected neurons in primate model of Parkinson's disease

October 24, 1999

MIAMI BEACH, FL, Oct. 25, 1999 -- Researchers from the Harvard Medical School and Alexion Pharmaceuticals, Inc. (Nasdaq: ALXN) today reported that the transplantation of immunoprotected pig neurons into non-human primate models of Parkinson's disease resulted in successful engraftment and function of the transplanted cells. Presented here at the 29th Meeting of the Society for Neuroscience, the study shows that the acceptance of the engrafted cells was enhanced through the use of Alexion's proprietary C5 Complement Inhibitor. 5G1.1, an anti-inflammatory C5 Inhibitor drug, is currently being tested in Phase II clinical trials for the treatment of various chronic inflammatory disorders.

Entitled "Xenotransplantation of Transgenic Fetal Pig Dopamine Neurons Into Monkey with Complement Inhibition," the report comes from the laboratories of Dr. Ole Isacson of the Neuroregeneration Laboratories, Harvard Medical School, McLean Hospital, in Belmont, MA, working in collaboration with scientists from Alexion Pharmaceuticals, Inc., New Haven, CT.

Parkinson's disease is a progressive disorder of the central nervous system affecting over one million people in the United States. Clinically, the disease is characterized by a decrease in spontaneous movements, rigidity and tremor. Parkinson's disease is caused by the degeneration of the dopamine-producing neurons in the substantia nigra of the brain, resulting in decreased dopamine availability.

In the study, these scientists demonstrated that transplantation of neurons from Alexion's transgenic pigs restored dopamine production locally and selectively in the affected part of the brain in primates with Parkinson's-like disease. Additionally, the results show that the activity of Alexion's pharmaceutical C5 Inhibitor further improved the survival of the immunoprotected neurons.

"The combined use of Alexion's dual immunoprotective technologies now offers hope for a significant improvement in the survival of these neural grafts," said Dr. Isacson. "In fact, to my knowledge, this study represents the first successful engraftment of pig neurons into primates. It further demonstrates that the combination of these immunoprotected neural cells with the pharmaceutical C5 Inhibitor, may provide an optimal means to overcome the critical immune barrier that has historically limited successful engraftment."

Specific antibody binding to the surface of a foreign cell initiates a process called the "complement" cascade, which results in the destruction of the foreign cell. Previously, these Harvard and Alexion researchers reported that pig neurons were shown to be sensitive to destruction by complement proteins. Alexion's technologies address this problem in three ways. First, pig cells are modified to reduce or eliminate the expression of certain pig sugars which are targeted by the complement-triggering antibodies. Second, dopamine-producing pig cells are further modified to express a protective shield of human complement inhibitor proteins. Third, the transplant recipient will be administered a clinically tested C5 Complement Inhibitor drug.

Alexion's C5 complement inhibitors are specific and potent recombinant anti-inflammatory drugs which are designed to intervene in the complement cascade. The company believes that these proprietary C5 inhibitors intervene at an optimal point which generally preserves the normal disease-preventing functions of complement proteins while generally inhibiting the disease causing actions. 5G1.1 is a novel fully humanized monoclonal antibody, specifically designed to deliver potent anti-complement and anti-inflammatory activity to patients suffering from chronic inflammatory diseases, including rheumatoid arthritis, membranous nephritis and systemic lupus. 5G1.1 is currently being tested in Phase II safety and efficacy trials in rheumatoid arthritis and membranous nephritis patients.

"Tapping the full breadth of our immunoregulatory technologies, a combination of our C5 Inhibitor drug and our modified pig neurons may provide a novel therapy aimed at restoring function to Parkinson's disease patients," said Leonard Bell, M.D., president and chief executive officer of Alexion. "We are now focusing on optimizing manufacturing and beginning to explore the process of initiating human clinical trials."

"Transplantation of dopamine-producing neurons represents a promising approach with the potential to effectively treat Parkinson's disease," said Dr. James M. Schumacher of Neurological Associates of Sarasota, Florida, who specializes in the surgical treatment of Parkinson's disease and was the first physician to transplant pig neurons into human patients. "Unfortunately, the difficulty of obtaining such cells for transplantation has slowed research in this area. This study is very exciting because it supports a new approach to obtaining an unlimited source of cells for transplantation in Parkinon's disease patients." Dr. Schumacher is an independent consultant to Alexion's cell replacement programs.

Alexion Pharmaceuticals, Inc. was founded in 1992 and is engaged in the development of selective immunotherapeutic drugs that generally are designed to inhibit the disease-causing segments of the immune system while preserving the disease-preventing aspects of the immune system. The Company is developing three technology platforms: C5 Complement Inhibitors and Apogen T-Cell Therapeutics which together target severe cardiovascular and autoimmune disorders; and xenograft cells for cell replacement therapy. Xenotransplantation refers to the transplantation of non-human cells, tissues and/or organs into human patients.

This news release contains forward looking statements. Such statements are subject to certain factors which may cause Alexion's plans to differ or results to vary from those expected including unexpected pre-clinical or clinical results, the need for additional research and testing, delays in manufacturing, access to capital and funding, delays and adverse changes in development of commercial relationships and a variety of risks set forth from time to time in Alexion's filings with the Securities and Exchange Commission, including but not limited to the risks discussed in Alexion's Annual Report on Form 10-K for the year ended July 31, 1998. Alexion undertakes no obligation to publicly release results of any of these forward looking statements which may be made to reflect events or circumstances after the date hereof or to reflect the occurrence of unanticipated events.
Editor's Note: This release is available on the Internet at http://www.noonanrusso.com for immediate release


Alexion Pharmaceuticals, Inc.
Leonard Bell
President & CEO
203-776-1790 Ext. 103
email: BellL@ALXN.com

Noonan/Russo Communications, Inc.
Ernie Knewitz
212- 696-4455 Ext. 204
email: news@noonanrusso.com

Noonan/Russo Communications

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