From: Howard Rothenburg (hrothenb@bcpl.net)
Date: Mon Jan 17 2000 - 22:24:36 MST
Biotech Firms Transforming Animals Into Drug-Producing Machines
>From the BREAKING NEWS discussion group
_____
Hey Newswatchers,
Just wanted to add one news item to the discussion on cloning. A story in
today's San Francisco Chronicle talks about the injection of human genes
into animals, a practice called transgenics. The idea is to incubate
proteins that be extracted from the animals and used to fight diseases in
humans. Another noble endeavor, but does it raise more questions?
*********
Biotech Firms Transforming Animals Into Drug-Producing Machines
By Tom Abate
[From San Francisco Chronicle]
Several biotech firms in the United States and Europe are giving new meaning
to the slogan ``Got milk?''
These companies have spliced a few human genes into the DNA of goats, sheep,
pigs and other mammals.
These human genes are designed to produce, in the animal's milk, a specific
therapeutic protein to combat a human disease.
For instance, the animal might be bioengineered to produce a protein to
treat hemophilia.
The therapeutic protein would be extracted from the milk, purified and
packaged as a drug.
Putting genes from one creature into another is called transgenics. In
short, these transgenic animals are being groomed as four-legged drug
factories.
Transgenic drug production remains experimental.
The standard way to brew drugs is in huge stainless steel vats in a
fermentation process that makes protein factories look like wineries.
Proponents of transgenic production say animals will ultimately provide less
expensive factories.
Last week at a health science conference in San Francisco, a Massachusetts
firm called Genzyme Transgenics announced an important milestone in the
process of getting transgenic animals approved as protein therapy producers.
The company announced positive results from a Phase III trial of an
anti-clotting protein derived from the milk of a transgenic goat.
Phase III trials are usually the last experiment before a company seeks Food
and Drug Administration approval to sell a product. But because this process
is so novel, Genzyme Transgenics is running a second Phase III study to
gather additional safety data.
``Toward the end of the year, we would expect to have the two studies in
hand,'' said Genzyme Transgenics CEO Sandra Nusinoff Lehrman, who must
ultimately decide whether to ask the FDA to OK the first therapeutic protein
produced from a transgenic animal.
Genzyme Transgenics has half a dozen similar trials under way, a little
earlier in the testing process, to determine whether goats, rabbits and cows
can reliably produce high-quality therapeutic proteins in their milk.
PPL Therapeutics in the United Kingdom is experimenting with transgenic
sheep's milk to produce protein drugs for cystic fibrosis and hemophilia.
Pharming NV, a biotech firm in the Netherlands, is testing whether
transgenic rabbits, cows and mice can produce a variety of human proteins
for stomach ailments and other bleeding disorders.
Bill Drohan, a senior research director for the American Red Cross, is
collaborating with Pharming to create transgenic pigs to make the protein
raw material for a new surgical bandage.
Drohan explained that human blood contains a protein called fibrinogen,
which forms thin tendrils across a wound to trap blood and form a clot.
``If you look at a fresh scab, 90 percent of it is fibrinogen,'' Drohan
said.
The idea behind the bandage is simple: Smear fibrinogen on a bandage and
slap it on a wound. ``Early tests show this can stop any type of bleeding in
15 seconds,'' he said, even gushing wounds that normally prove fatal.
Not surprisingly, the U.S. Army would love to put such miracle bandages in
every medical field kit. The problem, Drohan said, is that today fibrinogen
is extracted from human plasma, and the Red Cross can't imagine getting
enough plasma donors to meet the likely demand.
Enter the transgenic pigs. ``The value of transgenic animals is that they
can make large quantities of safe material at reasonable costs,'' Drohan
said.
Producing protein drugs through current manufacturing processes means
building factories that can cost upwards of $150 million. Lehrman, the
Genzyme Transgenics CEO, said animal production systems should require lower
capital outlays.
Not that the process is cheap, fast or easy -- yet. Scientists must first
harvest the female animal's eggs, fertilize them in vitro and implant human
genes into these embryos to produce the desired therapeutic protein.
These transgenic embryos must then be transplanted into surrogate mothers,
who would give birth to the animals. Once they grow to adulthood, the
animals that produce the highest concentration of drug in their milk are
bred to create a herd.
Lehrman estimates it would require 30 to 100 goats to produce enough refined
protein to supply a typical commercial drug program. It might take two or
three years to create such a production herd.
Later this year, the FDA will hold a scientific meeting to consider the
safety issues raised by transgenic animal production of human therapeutics.
Drohan said one question is whether humans might develop allergic reactions
to proteins produced in animals. So far, this hasn't been a problem, but
regulators will take the issue seriously.
Another likely question is whether infectious agents in animals -- like mad
cow disease -- might somehow jump to humans. Lehrman said the key thing to
remember is that humans won't ingest the animal product directly. ``We have
a strong downstream pharmaceutical purification process,'' she said.
Given the number of transgenic animal products in human clinical trials, it
seems likely some will ultimately pass FDA muster. But even should animals
become approved as therapeutic protein factories, it's still way too early
to judge whether transgenic milk will ultimately supplant the stainless
steel vat or simply become a niche production method.
But the very prospect of using animals as drug factories is yet another
example of how biotechnology is altering the very fabric of life.
This archive was generated by hypermail 2.1.5 : Fri Nov 01 2002 - 15:26:18 MST