AIDS TREATMENT NEWS #226, July 7, 1995

Advances in organ and cell transplantation, and in basic immunology, have now raised the possibility of transplantation of organs or cells from animals to humans. For example, it is known that immune cells in baboons are resistant to HIV infection. If these cells could survive transplantation to humans, and could work properly in humans, they might conceivably provide immunological resistance to HIV, like human cells do -- except that the baboon cells could not be destroyed by the virus. If it works -- still a big if -- such a procedure might allow the reconstitution of an immune system in persons with late-stage AIDS.

The reverse -- transplantation of human immune cells to a baboon -- has already been done. So far the cells have survived, and tests indicate that proliferation responses are functional, according to treatment activists who have followed this work closely.

The first test of baboon to human cell transplantation was scheduled to have been tried already; the principal investigators are transplantation specialists at the School of Medicine of the University of Pittsburgh, and AIDS specialists at the University of California San Francisco Medical Center. Under the Federal regulations which were in effect until recently, such a test only needed to be approved by a local IRB (institutional review board). It did not need additional approval by the FDA -- just like a surgeon does not need FDA approval to try a new, experimental operation. But shortly before the first baboon to human transplant was to be done, the FDA expanded its authority into this new area, and told the researchers that they would have to get FDA approval first.

The researchers complied, postponing the trial and applying for FDA approval. However, animal to human transplantation involves major issues which must be considered -- including the theoretical risk of transmitting an animal disease to humans, conceivably even causing an epidemic. But this risk must be seen in perspective. Animal to human transplants have been attempted several times in the last 25 years, with some long-term engraftment; so far no dangerous animal diseases have been transmitted. And tens of thousands of people die every year because of lack of human organs to transplant.

Some experts believe that there should be more animal trials first, before attempts to transplant animal tissues into humans. But others fear that such trials will take years to finance, organize, and conduct, and cannot be definitive anyway. Sorting out all these heavy policy issues might take a long time, seriously delaying an early proof-of-concept trial.

The requirement for advance FDA approval could well mean, in practice, that the very difficult general policy issues for the whole field of "xenogeneic" (animal to human) organ and cell transplantation will have to be considered first -- before even the earliest proof-of-concept human trials can go forward. A bureaucracy usually prefers to delay making decisions in a completely new area, until it has a policy in place. If that happens in this case, it could disastrously delay the research. The alternative is to allow the small, early research to begin, even while the overall policy is being worked out.

These matters will be considered at a critical FDA meeting on July 13 and 14, at the Holiday Inn in Bethesda, Maryland. This meeting is open to the public.

David Hook, of the Xenogeneic Committee of ACT UP/Golden Gate in San Francisco, told AIDS TREATMENT NEWS that people should call the FDA's Office of AIDS and Special Health Issues, 301/443-0104, to tell the FDA that the baboon transplantation trial should go forward without delay.

For more information, including on how you can be involved, leave a message for David Hook on the voicemail of ACT UP/Golden Gate, 415/252-9200.

Comment Until now most of the AIDS community has known little about this issue, which has been brewing quietly behind the scenes for about two years. Those involved preferred not to seek publicity until recently, when the research was threatened with long delays.

But now the activists and researchers who want to move this research forward do need public support. This situation presents a challenge to the AIDS community. We must get up to speed quickly in this complex and difficult area; otherwise, decisions seriously harmful to people with AIDS are likely not only to be made, but also to become institutionalized.

[Note: This preliminary article is based on interviews with treatment activists, and on published information. Due to time constraints, we did not interview the researchers.]