Should the FDA stare at transgenic goats?

By Gareth Macdonald

- Last updated on GMT

Positive noises from an FDA panel on GTC Biotherapeutics’ recombinant antithrombin ATryn may further the use of transgenic animals for drug production but should the manufacturing process rather than the drug’s safety be our prime concern?

ATryn, which is made in the milk of genetically engineered goats and has been available in Europe since 2006, received a positive recommendation from the US Food and Drug Administration’s (FDA) Blood Product’s Advisory Committee (BPAC) according to minutes published yesterday on the basis of its safety and efficacy.

One slight downside for GTC was the BPAC's statement that the limited amount of repeat use data meant that further information on ATryn’s immunogenic potential would be required. However the committee was positive about the firm's plans to conduct a post-marketing immunosurveillance study.

While not bound by these opinions, their upbeat tone means that the FDA approval panel’s discussion of ATryn taking place on Friday is sure to be of interest to GTC's competitors. Companies like Pharming, Novo Nordisk and Hematech all have transgenic animal derived products on their books.

The FDA is expected to issue a final approval decision on allowing GTC to sell ATryn in the world's biggest drug market early next month.

GTC chairman Geoffrey Cox told the Associated Press​ that the FDA’s decision is a tipping point for the firm and for the use of modified animals for protein production, or “pharming” as it is known.

He emphasised that: "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​."

If approved, ATryn will be produced by GTC’s 200 strong herd of genetically modified goats at its headquarters in Massachusetts.

The extraction process is remarkably straightforward, the animals are milked twice a day and the ATryn protein is then collected and purified using technology developed by France’s LFB Biotechnologies.

Despite the upbeat mood at GTC, some groups have raised concerns about the use of genetically modified animals in industrial production with some of the strongest criticism coming from the US’ Center for Science in the Public Interest (CSPI).

CSPI spokesperson Greg Jaffe told USA Today​ that: "The regulatory process seems to have put the cart before the horse, analyzing the safety of the product before it has opined on the safety of the manufacturing process, [The] FDA clearly needs to impose cradle-to-grave conditions to prevent the goats from leaving the farm or their products from entering the food supply."

Recombinant clotting factor market

In 2007, the only commercially available recombinant factor VIIa product NovoSeven, which is produced by Novo, generated revenues of 5.86bn Danish kroner ($1.2bn), up 10 per cent on the previous year.

Unsurprisingly GTC is not the only company to be targeting this lucrative market. In addition to ATryn, the BPAC also issued positive opinion about CSL's Riastap this week. Another potential competitor is US firm Maxygen announced plans to initiate clinical trials of its anti-throbin drug MAXY-VII last year.

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