Blood Clotting Drug, ATryn, From Genetically Engineered Goats Approved By FDA

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Main Category: Blood / Hematology
Also Included In: Genetics
Article Date: 07 Feb 2009 - 7:00 PDT

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The FDA (Food and Drug Administration) has approved the first ever biological product produced by a genetically engineered animal - a goat. ATryn is an anticoagulant, used for the prevention of blood clots. It is for patients who have a rare disease known as AT (hereditary antithrombin) deficiency. Patients are at high risk of blood clots when they undergo medical intervention such as surgery, and during/before and after childbirth.

Derived from the milk of goats, ATryn is a therapeutic protein. The goats have been genetically engineered (GE) by introducing a segment of DNA into their genes (DNA or rDNA construct) with instructions for the goat to produce human antithrombin in its milk. Antithrombin occurs naturally in healthy humans - it helps keep blood from clotting in blood vessels.

GTC Biotherapeutics, Inc., the manufacturer of ATryn, received approvals from two FDA centers. The Center for Biologics Evaluation and Research (CBER) approved the human biologic based on its safety and efficacy, and the Center for Veterinary Medicine (CVM) approved the rDNA construct in the goats that produce ATryn.

Jesse Goodman, M.D., M.P.H., CBER director, said "This product offers an important new treatment option for patients with hereditary antithrombin deficiency, preventing life-threatening clots that otherwise frequently occur during high risk situations,"

As AT deficiency only occurs in 1 in every 5,000 people in the USA, the FDA granted ATryn an orphan drug destination - a system which encourages the development and delivery of drugs for very rare diseases and conditions. The FDA held an advisory committee meeting in January to seek the opinion of outside experts, who agreed that ATryn is safe and effective. CVM also briefed the committee about the animal drug components of the application.

Hereditary AT deficiency generally is first recognized and diagnosed in teenagers or young adults when they develop clots in their blood vessels, particularly during pregnancy, surgery, or prolonged bed rest.

CBER looked at two studies involving 31 patients with hereditary AT deficiency who received ATryn to prevent thromboemboli (TE) before, during or after surgery or childbirth. All but one patient had a prior history of at least one TE, which is likely to recur in high-risk situations if left untreated. Only one of the 31 patients treated with ATryn developed a TE. The most common adverse reactions reported were hemorrhage and reactions at the infusion site. These reactions occurred in approximately five percent of patients.

As part of its review of the GE goat, CVM assessed the safety of the rDNA construct to the animals, including a full review of the construct and its stability in the genome of the goats over seven generations. No adverse outcomes were noted. CVM reviewed and concurred with the sponsor's plan to continue to monitor the construct and its expression for the lifetime of the approved product.

CVM determined that introduction of the rDNA construct did not cause any undesirable side effects to the health of the goats over seven generations. CVM also determined that the manufacturer, GTC, has adequate procedures in place to ensure that food from these goats does not enter the food supply. As part of the approval, CVM specified that these goats cannot be used for food or feed and validated a method suitable for identifying the rDNA construct in both animals and their products. CVM also determined that the GE goats do not cause any significant impact on the environment.

Bernadette Dunham, D.V.M., Ph.D., CVM director "We have looked carefully at seven generations of these GE goats; all of them are healthy and we haven't seen any adverse effects from the rDNA construct or its expression. I am pleased that this approval makes possible another source of an important human medication."

A summary of the information on which the FDA made its approval decision for the rDNA construct in the goats, and CVM's guidance on the regulation of GE animals containing heritable rDNA constructs are available here.

ATryn previously received approval from the European Medicines Agency for use in preventing clotting conditions during surgical procedures in patients with hereditary AT deficiency.

ATryn is manufactured by GTC Biotherapeutics, Inc., Framingham, Mass.

Source - FDA.

Written by - Christian Nordqvist


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