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254Goats Engineered To Provide Meds In Milk

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  • Imp Ster
    Jan 7, 2009
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      Drug from genetically engineered goats a first

      WASHINGTON – You've heard of making cheese from goats' milk, but
      prescription drugs? In what would be a scientific first, an
      anti-clotting drug made from the milk of genetically engineered goats
      moved closer to government approval Wednesday after experts at the
      Food and Drug Administration reported that the medication works and
      its safety is acceptable.

      Called ATryn, the drug is intended to help people with a rare
      hereditary disorder that makes them vulnerable to life-threatening
      blood clots.

      Its approval would be a major step toward new kinds of medications
      made not from chemicals, but from living organisms genetically
      manipulated by scientists. Similar drugs could be available in the
      next few years for a range of human ailments, including hemophilia.

      ATryn was developed by a Massachusetts biotechnology company, GTC
      Biotherapeutics, by altering the genes of goats so they would produce
      milk rich in antithrombin, a protein that in humans acts as a natural
      blood thinner.

      About 1 in 5,000 people don't produce enough of the protein, putting
      them at risk of developing blood clots in their veins. Such clots can
      be extremely painful. If they break loose and travel through the
      bloodstream to the lungs or the brain, the consequences can be
      catastrophic. Pregnant women with the disorder are at high risk of
      miscarriage or stillbirth, because of blood clots in the placenta.

      In their everyday lives, patients with antithrombin deficiency are
      managed with conventional blood thinners. That would not change. ATryn
      is for use only when patients are undergoing surgery or having a baby,
      times when the risk of dangerous clots is particularly high. Those
      patients would receive the drug by intravenous infusion for a limited
      time before and after their procedures.

      Karen Janes of Santa Fe, N.M., whose teenage daughter Mary Karen died
      of a brain clot linked to the disorder, said the issue is whether the
      drug works, not how it is made.

      "I think this goat thing is just wonderful," said Janes. "I do want
      this drug to go through all the rigors of testing by the FDA. But if
      it can work, and it can save other families from what we went through,
      I think that's marvelous." Her daughter died in 1998.

      Scientific advisers to the FDA will weigh the risks and benefits of
      ATryn at a meeting Friday, and make a recommendation on approval. The
      FDA will make the final decision.

      "It's the first time we've held an advisory committee meeting on any
      product from a genetically engineered animal," said FDA spokeswoman
      Siobhan DeLancey. If the drug is approved, the FDA may require
      follow-up monitoring to make sure that patients' immune systems don't
      start making antibodies in reaction to the medication.

      "I think this is an important tipping point," said Geoffrey Cox,
      chairman of GTC, the drug maker. "The real dramatic thing that is
      happening here is that we've been able to reduce some very clever
      science to the practical level of producing a drug that's safe and
      efficacious. Those things aren't trivial."

      To make the drug, scientists at GTC put DNA for the human antithrombin
      protein into single cell embryos of goats. Goat embryos with the gene
      were then inserted into the wombs of surrogate mothers who gave birth
      to baby goats carrying the new trait.

      The first of these goats were called the "founders." Their offspring
      also carry the gene. The females produce high levels of antithrombin
      in their milk, from which the protein is collected and purified.

      GTC's production comes from a herd of about 200 goats on a farm in
      central Massachusetts, milked twice a day. They look no different from
      any other goats.

      Up to now, antithrombin has been produced from blood products
      collected from human donors. Making the protein from goats may be
      better for humans, said Dr. Stephan Moll, a hematologist at the
      University of North Carolina, Chapel Hill, who consults for the
      company. It would ensure a steady supply and reduce concerns about

      "It's a new mechanism by which drugs could be produced in pretty large
      volume in the future," said Moll, who is also a top medical adviser to
      the National Alliance for Thrombosis and Thrombofilia, a group that
      represents patients with the blood disorder.

      ATryn has already been approved in Europe.