Findings support continued research to develop potentially life-saving technology
Basel, 19 August 1999 -- Evaluation of the largest ever retrospective study to assess the safety of xenotransplantation, the transplantation of cells, tissues or organs from one species to another, shows there is no evidence of Porcine Endogenous Retrovirus (PERV) infection in 160 patients previously treated with living pig tissue. Reported today in the journal Science, the study was run by Imutran Ltd., the Novartis Pharma AG company at the forefront of xenotransplantation research.
"This study is an important milestone in the development of this potentially life-saving technology," said Dr Corinne Savill, Chief Operating Officer, Imutran. "We hope in the long-term that this will help to save the lives of patients worldwide waiting for an organ transplant."
The purpose of the study was to determine whether there had been transmission of PERV to patients treated with living pig tissue, and if so, whether there was any evidence of harm. PERV DNA is not known to cause any harm in pigs. It is found in the pig's genetic material and is inherited from one generation to the next.
In order to run the study, Novartis had to search the world for doctors who had treated their patients with living pig tissue. The patients included in the study had been treated up to twelve years previously with pig skin grafts for severe burns, pig pancreatic islet cells for diabetes or had their blood perfused outside the body through pig spleens, kidneys or livers. Samples from these patients were tested using the most advanced, state-of-the-art technology available. The protocol included three different tests to see whether there had been any infection by or transmission of the pig virus. Samples from the patients were tested in different laboratories and were provided to the United States Centers for Disease Control and Prevention to confirm the findings.
The study showed that there is no evidence of PERV infection in 160 patients, including 36 patients who were pharmacologically immunosuppressed and therefore presumed to be at increased risk of infection. Twenty three patients showed clear evidence of circulating pig cells, but no infection even though some of these patients had been treated with living pig tissue more than eight years previously. This finding demonstrates that pig tissue can survive in the human body for long periods with no ill effects.
Four patients had a positive response in the antibody test. The other two tests showed no evidence of virus or its DNA in the patients' blood. The most likely explanation is that the antibodies were pre-existing in these patients, or were there due to cross reactivity with an unrelated antigen. In two of the four patients there were previous samples which indicated that the antibodies were already present at the time of treatment. Unfortunately, there were no earlier samples for the remaining two patients but these two patients were negative in the other tests looking for evidence of PERV DNA and circulating virus.
"Our next step is to refine the combination of medicines that patients will need to protect their xenotransplant from rejection," said Dr Paul Herrling, Head of Research, Novartis Pharma AG. "If these studies are as positive as the results of our safety research, we can then consider the next step which is small, carefully monitored clinical trials."
"We have learned a great deal from this study," said Dr Kaz Paradis, Director of Clinical Research, Imutran. "But it is important to remember that any move to clinical trials will only take place following open discussion with scientific and clinical experts, and with full approval from the appropriate regulatory authorities."
"This study adds considerably to the breadth and depth of the knowledge that the scientific community continues to accumulate as we explore the potential for xenotransplantation in the clinical setting, " said Sir Roy Calne FRS, Emeritus Professor of Surgery, Cambridge University, UK.
Currently there are thousands of people all over the world waiting for a new heart or kidney which may transform their lives. Potentially, a safe and effective xenotransplantation programme could provide enough healthy organs to offer transplantation to these patients.
For more than 15 years, Novartis has helped improve the quality of life for transplant recipients. The introduction of cyclosporine in the early 1980s dramatically increased the success rate of transplantation and helped make solid organ transplants the routine procedures they are today.
Novartis is a world leader in Life Sciences with core businesses in Healthcare, Agribusiness and Consumer Health (Nutrition and Self-Medication). In 1998, Novartis Group sales were CHF 31.7 billion, of which CHF 17.5 billion were in Healthcare, CHF 8.4 billion in Agribusiness and CHF 5.8 billion in Consumer Health. The group annually invests more than CHF 3.7 billion in R&D. Headquartered in Basel, Switzerland, Novartis employs about 81,000 people and operates in over 100 countries around the world.
Reference:
1. Paradis K et al. Search for cross species transmission of porcine
endogenous retrovirus in patients treated with living pig tissue. Science 1999;
285, 1236-1241.
Note to Editors:
Visuals and further background information about the study can be found on the following web sites:
www.novartis.com
www.pharma.novartis.com
Journal
Science