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GTC Biotherapeutics receives notice of allowance on purification patent

03 Aug 2005 - GTC Biotherapeutics, Inc. announced that the United States Patent and Trademark Office has issued a notice of allowance for the claims in its patent application 10/635,117 covering tangential flow filtration technology. These claims provide GTC with a unique position in the use of this technology to recover recombinant therapeutic proteins that are expressed in the milk of transgenic animals. The patent that issues from this application will expire in 2023.
 
Tangential flow filtration is an initial product recovery step that removes fats and other colloidal proteins such as casein from milk containing the target protein of interest. This approach also allows for the significant reduction in volume of the milk while yielding a material that can be aseptically processed. The resulting partially purified intermediate bulk product is more stable than unprocessed milk and can be stored for extended periods either refrigerated or frozen. The intermediate bulk product is then taken through additional purification steps, typically chromatography, to obtain a highly purified form of the desired therapeutic protein.
 
GTC is able to produce a therapeutic protein in an animal's milk through a process known as transgenic technology. GTC couples the gene expressing a specific protein with a specific milk protein promoter gene and incorporates it into an animal's genome such that the protein is expressed during lactation. This approach has been demonstrated to enable the production of therapeutic proteins that are difficult to express in traditional production methods. For products that can be expressed in conventional recombinant technology, transgenic technology has significantly lower capital requirements to establish large volume capacity.