BioTransplant and Massachusetts General Hospital Announce Clinical Success with End-Stage Renal Disease and Multiple Myeloma

- Advances May Lessen Life-long Use of Immunosuppressive Drugs -



Apr 19, 2001, 01:00 ET from BioTransplant Incorporated and Massachusetts General Hospital

    CAMBRIDGE, Mass., April 19 /PRNewswire Interactive News Release/ --
 BioTransplant Incorporated (Nasdaq:   BTRN) and the Massachusetts General
 Hospital (MGH) announced today the continuing success of a double transplant
 procedure that frees the patient from the need for whole body irradiation to
 treat cancer.  The procedure also eliminates the need for life-long
 immunosuppressive drugs to prevent donor graft rejection.  Results of the
 treatment of two patients with end-stage renal disease secondary to multiple
 myeloma will be presented at the Transplant 2001 Meeting in Chicago on May 14,
 2001, by scientists from the MGH.
     Multiple myeloma is a cancer of the bone marrow that causes the
 proliferation of abnormal plasma cells.  This disease can lead to reduced
 levels of red cells and platelets, tumors at multiple sites, kidney or heart
 failure or life-threatening infections.  No rejection episodes have occurred,
 and both patients continue with normal kidney function without progression of
 myeloma for over 2.5 years and 6 months respectively, in the absence of
 chronic immunosuppressive drugs.  This represents a significant advance toward
 the time when transplant recipients can be made tolerant to donors' organs
 without the risks and costs of life-long immunosuppression.
     The treatment uses a less toxic preparation for bone marrow transplant
 that was developed at the Bone Marrow Transplantation Unit at MGH and is a
 prototype of BioTransplant's proprietary AlloMune(TM) System for cancer.
 Patients are prepared for transplant with a combination of mild chemotherapy
 and antibodies against T cells, the immune cells that are responsible for
 attacking transplanted tissues.  This novel approach allows the patient to
 accept the donor marrow but preserves most of his or her own marrow, leading
 to the blended immune system described as "mixed chimerism."  The immune
 systems of the donor and recipient are mixed in a way that prevents rejection
 of the transplanted kidney by the recipient's body and suppresses an attack by
 the donor's immune cells on the recipient's organs, a dangerous condition
 called graft-vs-host disease.  While the chimeric state keeps donor cells from
 attacking the recipient's healthy tissues, cancerous cells are not protected.
 Additional delayed infusions of donor leukocytes (DLI) can further enhance the
 anti-tumor effect in chimeric recipients.  The MGH and BioTransplant have been
 studying mixed chimerism and its applications for both inducing tolerance of
 organ transplants and fighting blood cell cancers for several years.
     A. Benedict Cosimi, M.D., Chief of the MGH Transplantation Unit, and
 Claude E. Welch Professor of Surgery at Harvard Medical School said, "This is
 the first time that this has ever been done.  We know that tolerance can
 develop and that some patients have been able to discontinue immunosuppressive
 therapy but didn't know why.  This is the first deliberate up-front effort to
 create tolerance."  He noted that two clinical trials are expected to begin
 this year, one in patients with kidney failure and multiple myeloma and the
 other in patients with comparatively uncomplicated kidney transplants.
     Megan Sykes, M.D., Director of the Bone Marrow Transplantation Section and
 Professor of Surgery and Medicine at Harvard Medical School observed, "Our
 research efforts are focused on creating and improving clinical procedures
 that will obviate the need for long-term immunosuppressive treatment in the
 transplantation of cells and organs.  The milder conditioning regimen has the
 potential to enable treatment for a wider range of cancers and blood cell
 abnormalities."
     In further studies presented at the meeting by Juanita Shaffer, blood
 cells were taken from the patients to monitor their T cell recovery and immune
 responses to donor cells.  Results confirm that mixed chimerism may be vital
 for the initial acceptance of organ transplants and the successful treatment
 of blood cancers.
     Elliot Lebowitz, Ph.D., BioTransplant's President and C.E.O. said, "We are
 excited by the results of these studies that suggest we are approaching the
 day when patients receiving transplants and cancer therapy can do so without
 life-long immunosuppression.  We will continue to develop our AlloMune Systems
 that seek to break new ground in the treatment of malignancies.  We are
 progressing toward commercialization of these systems as we build on our
 successes in the clinic"
     Previously, U.S. patents (nos. 6006752 and 5876708) entitled "Mixed
 Chimerism and Tolerance" and "Allogeneic and Xenogeneic Transplantation" were
 issued and licensed exclusively to BioTransplant.  The company believes that
 this technology will significantly expand the number of blood cell cancers and
 organ transplant patients who can be treated, produce fewer side-effects in
 these patients and reduce or eliminate the need for long-term
 immunosuppressive drug treatments.
     BioTransplant's AlloMune Systems are also under evaluation for therapy-
 refractory lymphoma. By transplanting donor bone marrow, the AlloMune System
 for cancer applications is designed to more aggressively attack tumor cells
 than the patient's own immune defenses. Additional, potential indications for
 the AlloMune family of products include hematological disorders, autoimmune
 diseases and other types of cancer. BioTransplant is developing the AlloMune
 System for kidney transplantation to facilitate organ acceptance without the
 need for long-term immunosuppressive anti-rejection drugs. The company has
 previously demonstrated long-term (multi-year) survival of fully mismatched
 and life supporting donor kidney grafts in non-human primate models without
 chronic immunosuppression.
 
     The Massachusetts General Hospital, established in 1811, is the original
 and largest teaching hospital of the Harvard Medical School and conducts the
 largest hospital-based research program in the United States.  The MGH has
 major research centers in transplantation biology, the neurosciences,
 cardiovascular research, cancer, AIDS, cutaneous biology and photomedicine.
 Along with the Brigham and Women's Hospital, the MGH is a founding member of
 Partner's HealthCare System, Inc. an integrated health care delivery system
 comprising the two academic medical centers, specialty and community
 hospitals, a network of physician groups and non-acute and home health
 services.
 
     BioTransplant Incorporated utilizes its proprietary technologies to re-
 educate 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 for application in a range of medical conditions,
 including organ and tissue transplantation, and treatment of cancer and
 autoimmune diseases, 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 release and additional information on
 BioTransplant is available on the Web at http://www.biotransplant.com
 
     This announcement contains, in addition to historical information,
 forward-looking statements about BioTransplant that involve risks and
 uncertainties. Such statements reflect management's current views and are
 based on assumptions. Actual results could differ materially from those
 currently anticipated as a result of a number of important factors. Factors
 that could cause future results to differ materially from such forward-looking
 statements include, but are not limited to: BioTransplant's ability to secure
 the substantial additional funding required in the near term for its
 operations and research and development programs; BioTransplant'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; BioTransplant's ability to obtain and enforce the patent
 protection required for its products; uncertainties relating to the extent of
 future government regulation of the transplantation business; and
 BioTransplant's ability to establish maintain collaborations and joint venture
 alliances with third parties. For a detailed discussion of these and other
 factors, see the section titled "Business -- Factors That May Affect Results"
 in BioTransplant's annual report on Form 10-K, as filed with the Securities
 and Exchange Commission.
 
     Contacts:
 
     BioTransplant Incorporated
     Elliot Lebowitz, Ph.D.
     President and CEO
     (617) 241-5200
     http://www.biotransplant.com
 
     Noonan/Russo Communications
     Prateek Patnaik (Media) x273
     Sharon Weinstein, (Investor), x334
     (212) 696-4455
     http://www.noonanrusso.com
 
     Massachusetts General Hospital
     Georgia Peirce
     Public Affairs
     (617) 724-6423
 
                     MAKE YOUR OPINION COUNT -- Click Here
                http://tbutton.prnewswire.com/prn/11690X18412141
 
 

SOURCE BioTransplant Incorporated and Massachusetts General Hospital
    CAMBRIDGE, Mass., April 19 /PRNewswire Interactive News Release/ --
 BioTransplant Incorporated (Nasdaq:   BTRN) and the Massachusetts General
 Hospital (MGH) announced today the continuing success of a double transplant
 procedure that frees the patient from the need for whole body irradiation to
 treat cancer.  The procedure also eliminates the need for life-long
 immunosuppressive drugs to prevent donor graft rejection.  Results of the
 treatment of two patients with end-stage renal disease secondary to multiple
 myeloma will be presented at the Transplant 2001 Meeting in Chicago on May 14,
 2001, by scientists from the MGH.
     Multiple myeloma is a cancer of the bone marrow that causes the
 proliferation of abnormal plasma cells.  This disease can lead to reduced
 levels of red cells and platelets, tumors at multiple sites, kidney or heart
 failure or life-threatening infections.  No rejection episodes have occurred,
 and both patients continue with normal kidney function without progression of
 myeloma for over 2.5 years and 6 months respectively, in the absence of
 chronic immunosuppressive drugs.  This represents a significant advance toward
 the time when transplant recipients can be made tolerant to donors' organs
 without the risks and costs of life-long immunosuppression.
     The treatment uses a less toxic preparation for bone marrow transplant
 that was developed at the Bone Marrow Transplantation Unit at MGH and is a
 prototype of BioTransplant's proprietary AlloMune(TM) System for cancer.
 Patients are prepared for transplant with a combination of mild chemotherapy
 and antibodies against T cells, the immune cells that are responsible for
 attacking transplanted tissues.  This novel approach allows the patient to
 accept the donor marrow but preserves most of his or her own marrow, leading
 to the blended immune system described as "mixed chimerism."  The immune
 systems of the donor and recipient are mixed in a way that prevents rejection
 of the transplanted kidney by the recipient's body and suppresses an attack by
 the donor's immune cells on the recipient's organs, a dangerous condition
 called graft-vs-host disease.  While the chimeric state keeps donor cells from
 attacking the recipient's healthy tissues, cancerous cells are not protected.
 Additional delayed infusions of donor leukocytes (DLI) can further enhance the
 anti-tumor effect in chimeric recipients.  The MGH and BioTransplant have been
 studying mixed chimerism and its applications for both inducing tolerance of
 organ transplants and fighting blood cell cancers for several years.
     A. Benedict Cosimi, M.D., Chief of the MGH Transplantation Unit, and
 Claude E. Welch Professor of Surgery at Harvard Medical School said, "This is
 the first time that this has ever been done.  We know that tolerance can
 develop and that some patients have been able to discontinue immunosuppressive
 therapy but didn't know why.  This is the first deliberate up-front effort to
 create tolerance."  He noted that two clinical trials are expected to begin
 this year, one in patients with kidney failure and multiple myeloma and the
 other in patients with comparatively uncomplicated kidney transplants.
     Megan Sykes, M.D., Director of the Bone Marrow Transplantation Section and
 Professor of Surgery and Medicine at Harvard Medical School observed, "Our
 research efforts are focused on creating and improving clinical procedures
 that will obviate the need for long-term immunosuppressive treatment in the
 transplantation of cells and organs.  The milder conditioning regimen has the
 potential to enable treatment for a wider range of cancers and blood cell
 abnormalities."
     In further studies presented at the meeting by Juanita Shaffer, blood
 cells were taken from the patients to monitor their T cell recovery and immune
 responses to donor cells.  Results confirm that mixed chimerism may be vital
 for the initial acceptance of organ transplants and the successful treatment
 of blood cancers.
     Elliot Lebowitz, Ph.D., BioTransplant's President and C.E.O. said, "We are
 excited by the results of these studies that suggest we are approaching the
 day when patients receiving transplants and cancer therapy can do so without
 life-long immunosuppression.  We will continue to develop our AlloMune Systems
 that seek to break new ground in the treatment of malignancies.  We are
 progressing toward commercialization of these systems as we build on our
 successes in the clinic"
     Previously, U.S. patents (nos. 6006752 and 5876708) entitled "Mixed
 Chimerism and Tolerance" and "Allogeneic and Xenogeneic Transplantation" were
 issued and licensed exclusively to BioTransplant.  The company believes that
 this technology will significantly expand the number of blood cell cancers and
 organ transplant patients who can be treated, produce fewer side-effects in
 these patients and reduce or eliminate the need for long-term
 immunosuppressive drug treatments.
     BioTransplant's AlloMune Systems are also under evaluation for therapy-
 refractory lymphoma. By transplanting donor bone marrow, the AlloMune System
 for cancer applications is designed to more aggressively attack tumor cells
 than the patient's own immune defenses. Additional, potential indications for
 the AlloMune family of products include hematological disorders, autoimmune
 diseases and other types of cancer. BioTransplant is developing the AlloMune
 System for kidney transplantation to facilitate organ acceptance without the
 need for long-term immunosuppressive anti-rejection drugs. The company has
 previously demonstrated long-term (multi-year) survival of fully mismatched
 and life supporting donor kidney grafts in non-human primate models without
 chronic immunosuppression.
 
     The Massachusetts General Hospital, established in 1811, is the original
 and largest teaching hospital of the Harvard Medical School and conducts the
 largest hospital-based research program in the United States.  The MGH has
 major research centers in transplantation biology, the neurosciences,
 cardiovascular research, cancer, AIDS, cutaneous biology and photomedicine.
 Along with the Brigham and Women's Hospital, the MGH is a founding member of
 Partner's HealthCare System, Inc. an integrated health care delivery system
 comprising the two academic medical centers, specialty and community
 hospitals, a network of physician groups and non-acute and home health
 services.
 
     BioTransplant Incorporated utilizes its proprietary technologies to re-
 educate 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 for application in a range of medical conditions,
 including organ and tissue transplantation, and treatment of cancer and
 autoimmune diseases, 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 release and additional information on
 BioTransplant is available on the Web at http://www.biotransplant.com
 
     This announcement contains, in addition to historical information,
 forward-looking statements about BioTransplant that involve risks and
 uncertainties. Such statements reflect management's current views and are
 based on assumptions. Actual results could differ materially from those
 currently anticipated as a result of a number of important factors. Factors
 that could cause future results to differ materially from such forward-looking
 statements include, but are not limited to: BioTransplant's ability to secure
 the substantial additional funding required in the near term for its
 operations and research and development programs; BioTransplant'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; BioTransplant's ability to obtain and enforce the patent
 protection required for its products; uncertainties relating to the extent of
 future government regulation of the transplantation business; and
 BioTransplant's ability to establish maintain collaborations and joint venture
 alliances with third parties. For a detailed discussion of these and other
 factors, see the section titled "Business -- Factors That May Affect Results"
 in BioTransplant's annual report on Form 10-K, as filed with the Securities
 and Exchange Commission.
 
     Contacts:
 
     BioTransplant Incorporated
     Elliot Lebowitz, Ph.D.
     President and CEO
     (617) 241-5200
     http://www.biotransplant.com
 
     Noonan/Russo Communications
     Prateek Patnaik (Media) x273
     Sharon Weinstein, (Investor), x334
     (212) 696-4455
     http://www.noonanrusso.com
 
     Massachusetts General Hospital
     Georgia Peirce
     Public Affairs
     (617) 724-6423
 
                     MAKE YOUR OPINION COUNT -- Click Here
                http://tbutton.prnewswire.com/prn/11690X18412141
 
 SOURCE  BioTransplant Incorporated and Massachusetts General Hospital