Monday October 25, 9:15 am Eastern Time
Company Press Release
SOURCE: BioTransplant Incorporated
Massachusetts General Hospital and BioTransplant
Report Research Advances for Cross-Species Transplantation
-- MGH and BioTransplant Scientists to Lead Discussions on Key Topics at International
Xenotransplantation Association Conference --
NAGOYA, Japan, Oct. 25 /PRNewswire/ -- The Massachusetts General Hospital (MGH) and BioTransplant Incorporated
(Nasdaq: BTRN - news) announced today their latest research advances in achieving long-term, cross-species transplantation.
These new approaches to xenotransplantation are being designed to modify immune system components of the recipient in
order to enable porcine tissue to be recognized and accepted by the recipient as ''self.'' Studies in animal models, presented in
37 oral and poster presentations this week by MGH and BioTransplant researchers at the 5th Congress of the International
Xenotransplantation Association held in Nagoya, Japan, indicate that these new approaches have the potential to create
tolerance to donor tissue, a significant goal of transplantation medicine.
''BioTransplant and MGH investigators have taken several fundamental approaches toward our goal of achieving acceptance
of xenografts. These approaches are focused on modifying recipient systems to induce tolerance to porcine grafts either by
creating a state of mixed chimerism or via porcine thymus transplantation,'' said David H. Sachs, M.D., of MGH.
''Furthermore, many of these approaches are designed to avoid the use of high levels of immunosuppression.''
''The outstanding presence by MGH and BioTransplant at this international congress underscores the value of our technology,''
said Elliot Lebowitz, Ph.D., President and Chief Executive Officer of BioTransplant. ''MGH, an important BioTransplant
collaborator, is conducting research that complements our xenotransplantation program; and we are pleased to deliver these
important advances with them at this week's meeting. In addition, our xenotransplantation program also includes commercial
alliances with Novartis.''
Approaches to Tolerance: Research Advances
BioTransplant and MGH investigators presented methods used to induce long- term tolerance to xenografts across major
transplantation barriers through the use of porcine thymic transplantation. Porcine thymic tissue does not appear to be sensitive
to rejection via natural antibodies, and when transplanted into a primate, inhibits T cell reactivity to pig antigen challenge. In
addition, BioTransplant and MGH presented further characterization of viruses in the miniature swine genome, continuing the
work to address long-term safety of xenotransplantation and potentially offering an additional benefit for the use of
BioTransplant's inbred miniature swine as organ donors.
BioTransplant and MGH investigators also presented studies demonstrating methods that decrease the immune response of
primates to pig tissues. These methods involve the creation of a donor and recipient blood cell population known as mixed
chimerism. Mixed chimerism in mouse models of xenotransplantation has allowed the permanent acceptance of donor hearts in
the absence of immunosuppressive drugs. Investigators also suggested that various protocols designed to enhance mixed
chimerism increase the tolerance to pig tissues. Methods to control destruction of pig cells in primates have increased the early
post-transplant pig cell chimerism by two to three fold and have been used to demonstrate early engraftment of porcine cells in
treated primates. These therapeutic approaches effectively block the sensitization of primate immune reactivity to the pig cells.
MGH and BioTransplant researchers described procedures to enhance the establishment of hematopoietic cell grafts through
the sustained expression of porcine cytokines. Using a transgenic mouse model, substantial numbers of porcine cells were
present at 20 weeks post-transplant in the porcine cytokine- expressing mice, while none were detected in the absence of
porcine cytokines.
Additional presentations were made showing that induction of mixed hematopoietic chimerism using potentially clinically
acceptable protocols may overcome another critical hurdle that affects the survival of pig grafts in humans: the hyperacute
rejection of pig xenografts caused by production of natural human antibodies to an epitope found on pig tissues. Antibodies
directed against cells that produce natural antibody have been shown to remove at least half of the pig-specific natural
antibodies in primates. The researchers investigated several protocols used to reduce or prevent the appearance of these
natural antibodies and to promote tolerance to pig xenografts in animal model systems.
ImmunoCognance(TM) Overview
BioTransplant's approach to transplantation, using functional tolerance, (ImmunoCognance(TM)), is based on work pioneered
by Dr. Sachs, a co- investigator on many of the studies presented at the meeting. ImmunoCognance(TM) may allow the
recipient's immune system to accept donor tissue as ''self'' without compromising the recipient's immune defenses. This is
achieved by mixing elements of the donor's immune system with that of the recipient. The AlloMune(TM) Transplant System,
for human-to-human transplantation, and the XenoMune(TM) System, for the transplantation of organs from BioTransplant's
proprietary miniature swine into humans, contain a number of advanced approaches which are being designed to facilitate the
acceptance of donor tissue by the human immune system.
The Massachusetts General Hospital, established in 1811, is the original and largest teaching hospital of Harvard Medical
School. The MGH conducts the largest hospital-based research program in the United States, with an annual research budget
of more than $200 million and major research centers in AIDS, the neurosciences, cardiovascular research, cancer, cutaneous
biology, transplantation biology and photomedicine. In 1994, the MGH joined with Brigham and Women's Hospital to form
Partners HealthCare System, an integrated health care delivery system comprising the two academic medical centers, specialty
and community hospitals, a network of physician groups and nonacute and home health services.
BioTransplant Incorporated utilizes its proprietary technologies in re- educating the body's immune responses to allow tolerance
of foreign cells, tissues and organs. Based on this technology, the Company is developing a portfolio of products designed to
treat a range of medical conditions, including organ and tissue transplantation, cancer and autoimmune disease, for which
current therapies are inadequate. BioTransplant's products under development are intended to induce long-term functional
transplantation tolerance in humans, increase the therapeutic benefit of bone marrow transplants, and reduce or eliminate the
need for lifelong immunosuppressive therapy.
This document includes forward-looking statements based on management's current expectations. Factors that could cause
future results to differ materially from such forward-looking statements include, but are not limited to: the Company's ability to
secure the substantial additional funding required for its operations and research and development programs; the Company's
ability to successfully discover, develop and commercialize its products, obtain required regulatory approvals in a timely
fashion, and overcome other difficulties inherent in developing pharmaceuticals and procedures for organ transplantation; the
Company's ability to obtain and enforce the patent protection required for its products; uncertainties as to the extent of future
government regulation of the transplantation business; and the Company's ability to maintain collaborations with third parties.
For a detailed discussion of these and other factors, see the section titled ''Business -- Factors Which May Affect Results'' in
the Company's current annual report on Form 10-K, as filed with the Securities and Exchange Commission.
Note to Editors:
For additional information on key developments and other areas of xenotransplantation, please be aware of the following
sessions at the conference:
Monday, October 25, 8:20 a.m. - 9:40 a.m.
David H. Sachs, M.D., MGH. Co-chair, Plenary Session B: ''Past Experience, Current and Future Strategies for Successful
Xenotransplantation.''
Megan Sykes, M.D., MGH; Professor, Harvard Medical School. Plenary Session B topic: ''Overcoming the Barriers to
Xenografts: Will Donor or Recipient Modification Be Enough?''
Tuesday, October 26, 4:00 p.m. - 5:30 p.m.
Aron Thall, Ph.D., BioTransplant Incorporated. Co-chair, Oral Abstract Session 20: ''Apoptosis.''
Wednesday, October 27, 10:00 a.m. - noon.
Clive Patience, Ph.D., BioTransplant Incorporated. Co-chair, Oral Abstract Session 23: ''Infections and Risks.''
Thursday, October 28, 9:00 a.m. - 10:20 a.m.
David K. C. Cooper, M.D., Ph.D., FRCS, MGH. Co-chair, Plenary Session E: ''Contemporary Issues in Tissue and Animal
Engineering.''
SOURCE: BioTransplant Incorporated |
