Recombinant human antithrombin III: rhATIII.

Abstract

GTC Biotherapeutics (formerly Genzyme Transgenics Corporation) is developing a transgenic form of antithrombin III known as recombinant human antithrombin III [rhATIII]. It is produced by inserting human DNA into the cells of goats so that the targeted protein is excreted in the milk of the female offspring. The transgenic goats have been cloned in collaboration with the Louisiana State University Agriculture Center. GTC Biotherapeutics is conducting clinical trials of rhATIII in coagulation disorders. rhATIII is believed to be both safer and more cost-effective than the currently available plasma-derived product. rhATIII is also being investigated in cancer and acute lung injury. Genzyme Transgenics Corporation, originally a subsidiary of Genzyme Corporation, changed its name to GTC Biotherapeutics in June 2002; it is no longer a subsidiary of Genzyme Corporation. GTC Biotherapeutics is seeking partners for the commercialisation of rhATIII. Restructuring of GTC Biotherapeutics to support its commercialisation programmes was announced in February 2004. Genzyme Transgenics Corporation was developing rhATIII in association with Genzyme General (Genzyme Corporation) in the ATIII LLC joint venture, but in November 2000 a letter of intent was signed for the reacquisition of the rights by Genzyme Transgenics Corporation. It was announced in February 2001 that this reacquisition was not going to be completed and that the development of rhATIII was to continue with ATIII LLC. However, in July 2001, Genzyme Transgenics Corporation reacquired all the rights in the transgenic antithrombin III programme. SMI Genzyme Ltd, a joint venture between Sumitomo Metal Industries, Japan, and Genzyme Transgenics Corporation, USA, was set up to fund development of transgenic antithrombin III in Asia. However, in October 2000, Genzyme Transgenics Corporation reacquired, from Sumitomo Metal Industries, the rights to its technology for production of medicines from milk in 18 Asian countries, including Japan. The 10-year-old joint venture, SMI Genzyme Ltd, was dissolved. In June 2002, GTC Biotherapeutics estimated the current market size for plasma ATIII products to be approximately $US250 million - of which sales in Europe amounted to $US110 million, Japan $US130 million and the US $US10 million.