Application for xenotransplantation trial declined
Ministry declines application for xenotransplantation trial
13 July 2001
Ministry declines application for xenotransplantation trial
DIRECTOR-General of Health Dr Karen Poutasi today declined an application for a clinical trial transplanting encapsulated pig cells into diabetic patients.
Dr Poutasi said all regulatory agencies in the developed world had concerns about the possibility of transmission of retroviruses through transplants of live pig tissues to humans.
The study proposes separating out the insulin-producing islet cells from two-week-old piglets, enclosing the cells within microcapsules and injecting the microcapsules into the abdomen of patients with type I insulin dependent diabetes.
The trial, proposed by New Zealand company Diatranz Ltd, is a preliminary study to determine the potential safety of the implantation of live animals cells into the human body (a process called xenotransplantation).
The experiment may also provide limited information about the effectiveness of xenotransplanted islet cells and may provide information on the dose needed to produce a clinical effect and the duration of effect of the transplanted cells.
As required by law, the Director-General's decision follows consideration of Diatranz's application by the Health Research Council's expert committee, the Gene Technology Advisory Committee (GTAC).
The expert committee advised that the study application contained a number of deficiencies and did not satisfactorily resolve the risk to public safety from xenotransplantation with respect to transmission of retrovirus infection. A similar application submitted by Diatranz in 1999/2000 was declined for the same reason.
The HRC has recommended that I decline the application and I have accepted this recommendation.
"There is uncertainty about the risk of transmission of retroviruses with xenotransplantation and the potential dire consequences for public health if this risk comes into being, means that a precautionary approach is needed," Dr Poutasi said.
The Ministry accepts this decision will be disappointing to some individuals willing to participate in the trial and to the researchers. This decision clearly demonstrates the balancing exercise that has to be taken between individual needs and wider public safety.
Although there is no evidence of transmission of retroviruses from pig islet cells to humans, there are published reports of transmission of retroviruses from one animal species to another following xenotransplantation. In the opinion of GTAC, the risk of transmission of retroviruses to the community through xenotransplantation cannot be ruled out .
"As the risk of xenotransplantation potentially extends beyond the transplant recipient to the wider community the public needs to be aware of the debate about this issue and participate where possible," Dr Poutasi said.
"I have decided to take the approach of the precautionary principle, which requires that the Ministry give the balance of doubt to protecting the community, should there be uncertainty about the evidence of risk or benefit, when considering such applications."
"When this approach is taken it is clear that given the outstanding safety issues, relating to the risk of transmission of retroviruses and other as yet unidentified organisms, declining the application is the most appropriate step to take at this point in time," Dr Poutasi said.
The Ministry of Health will continue to consider applications for clinical trials involving xenotransplantation on a case-by-case basis and will continue to monitor overseas developments. The Ministry will also be working closely with the Health Research Council's expert committee to review the latest studies on the risks posed by xenotransplantation. It is likely the "Precautionary Principle" will continue to apply until more about the safety and benefits of xenotransplantation is established.
For more information contact:
Anne-Marie Robinson, Media Advisor, ph: 04-496-2067 or 025-802 622
Internet address: http://www.moh.govt.nz/media.html
Questions and Answers What is xenotransplantation? Xenotransplantation is the transplantation of live cells, tissues or organs from animals (or animal origin) into humans. While patients have been implanted with pig heart valves for some time, these valves contain no living tissue and are inert. Xenotransplants are alive and will perform the same functions as any organ or cell. There are significant concerns that collecting, processing and transplanting of tissue from animals to humans may increase the risk of diseases of animals being transmitted to humans.
Is xenotransplantation new? The concept of xenotransplantation is not new. In the first decade of the twentieth century, there were a number of attempts at transplanting kidneys from one animal to another, but all resulted in failure. In 1905, a French researcher, Princeteau, wrote that a child with kidney inefficiency had received some slices of a kidney from a rabbit. The recipient died sixteen days later of congestion of the lungs. However, in all of these early cases aspirations far outstripped understanding.
With the emergence of effective anti-rejection medications, interest in xenografts resumed again in the 1960's. Experimental work predominately concentrated on kidney and heart xenografts and on several occasions patients received kidneys from a chimpanzee. Four of the human recipients died within weeks, but one, lived for nine months. Interest in xenotransplantation once again waned as it became clear that the anti-rejection drugs available were either too toxic or not up to the task.
What are the potential benefits of xenotransplantation? The main reason for medical scientists to explore the potential of xenotransplantation is to find alternatives for human organ and tissue transplants. Although many human transplant operations are highly successful, there is always a severe shortage of suitable donated organs and tissues. The greatest benefit would be to increase the supply available for transplantation.
How can it help cure disease or decrease health problems? Possible new therapies from xenotransplantation include the treatment of life-threatening or chronic debilitating illnesses. One example is diabetes - primarily caused by the destruction of islet cells which produce insulin in human bodies. One suggestion is the possibility of pig islets transplanted into a patient which may control his/her blood sugar levels. Other procedures include exploring the use of cells of tissues from other species to treat life-threatening illnesses such as liver failure and Parkinson's disease.
What are the risks? The greatest risk is rejection of a transplanted organ or tissue and this already occurs when human organs are used. However, in the case of xenographs, the organ rejection may be more severe since the differences between animal and human cells are greater. Another possible risk is that animal disease agents may be transmitted to the patient. Xenotransplants may also cause new types of infectious disease.
Is this the first application lodged in New Zealand relating to xenotransplantation? No. This is the fourth time such an application has been lodged by Diatranz. The first application was approved because it was before information about the transmission of a type of virus, known as Porcine Endogenous Retrovirus (PERV), to humans was published. The second application was withdrawn after this information was published and the most recent two applications have been declined because of concern about retroviruses.
Before the publication of the research demonstrating PERV could be transmitted to human cells, six diabetic patients in New Zealand received xenotransplants of pig islet cells as a treatment for their diabetes. In all cases the cells failed after several months. Subsequent testing has failed to reveal any evidence of transmission of PERV infection.
How would xenotransplants be controlled in New Zealand? In the opinion of the Ministry of Health, xenotransplantation of cells can be regulated within the New Zealand Medicines Act 1981. Xenotransplantation must therefore meet the same requirements for safety as any other clinical trial. Due to the nature of xenotransplantation research, New Zealand needs guidance on policy and guidelines from organisations such as the Food and Drug Administration before we can even consider whether xenotransplantation can occur in this country.
Can humans contract disease from this type of transplant? A number of diseases can be transmitted from animals to humans and scientists are discovering new infections on a regular basis. The recent outbreak of Nipah virus in Malaysia which caused several deaths, was spread by bats to pigs, and from pigs to humans. While many of these animal infections are either absent from New Zealand or can be found by testing of the animals, a number of other as present unknown viral conditions may exist. PERV is an example of a retroviral illness which was only recently identified. PERV is present in all pigs and cannot be removed by breeding or raising pigs in sterile facilities. At this stage we don't know how many or which infectious agents are potentially transmissible by xenotransplantation nor can we rule out the introduction of new human diseases from agents such as retroviruses which cause infection in animals. The most commonly known example of a retrovirus is HIV/AIDS.
Are pigs the only animals being considered as a future source of organs for transplantation in humans? In the opinion of scientists, transplant surgeons and animal welfare specialists, pigs are the most suitable animal to act as sources of tissues or organs for xenotransplantation. Pigs grow quickly, produce organs of a similar size to humans, produce large litters and can be reared in specific pathogen free conditions. In addition, pigs can be genetically manipulated to produce organs that are less likely to be rejected by human patients.
Will pig tissues function in humans? We do not know which tissues will function properly in the cross species setting.
What about concerns of transmitting infections? Many infectious agents of animal origin are also potential human pathogens and history shows that virulence of a pathogen may be increased if it adapts to infect a species other than the natural host. Some examples of cross-species infection include influenza, hantavirus infection, Ebola haemorrhagic fever and HIV/AIDS. This concern about possible cross species infection represents one of the major barriers to the introduction of xenotransplantation.
What are some of the issues for New Zealand? If in a worst-case scenario, a new infection emerged following xenotransplantation that could be transmitted to animals from the transplant recipient it could potentially have a dramatic ecological effect on native species that are regarded as taonga (treasures) by Maori and protected under the Treaty of Waitangi. It would also have a catastrophic effect on New Zealand's economy if it affected beef or lamb exports.
What action is being taken to ensure protective measures are in place? A number of countries including the United Kingdom, United States, Canada, Sweden and Spain have published draft guidelines to minimise the risk. The UK is accepting applications but has not yet approved any. Canada and Sweden have a moratorium in place have a moratorium in place until they have new laws and informed public debate has taken place. In Sweden it was projected this legislation would be passed sometime this year. In the US a small number of clinical trials have been given permission to go ahead. New Zealand is actively participating in this international dialogue on xenotransplantation.
What do these international guidelines require of participants in research?
Until more is known about the risks associated with xenotransplantation, international guidelines for participants in such research require that they:
not be of childbearing age and not have children after participation in the trial
notify health authorities of any sexual partners they have
practice safe sex
permit health authorities to closely monitor their families and any sexual contacts they may have, for the rest of their lives
not give blood or donate any organs or tissue
What is type 1 diabetes?
Diabetes is a metabolic disorder where the body is unable to control the amount of glucose in the blood. The level of blood glucose is controlled by insulin ? a hormone produced by the pancreas.
An estimated 11,000 people in New Zealand have type 1 diabetes. It is more common in European people than Maori or Pacific people. Most people with type 1 diabetes develop it as children or teenagers.
Anne Marie Robinson Media Advisor Ministry of Health DDI: 04 496 2067 Mobile: Fax: 04-496-2010