BioWorld International Correspondent

BRUSSELS, Belgium - GTC Biotherapeutics’ authorization bid for its recombinant antithrombin alfa, ATryn, suffered a setback late February, when experts at the European Medicines Agency voiced a negative opinion on the application, submitted by its licensee, Genzyme Europe.

The agency provided detail under its new public information policy about the committee’s concerns over the supporting data. But GTC told BioWorld International that it was exercising its right to request a re-examination from the agency’s Committee on Human Medicinal Products (CHMP).

"We will vigorously pursue the appeal process," said Thomas Newberry, GTC’s vice president, corporate communications.

The decision comes just one year after the agency started reviewing ATryn’s application - for prophylaxis of deep-vein thrombosis and thromboembolism in patients undergoing surgery with congenital antithrombin deficiency.

"Despite the setback we recently received in the approval process for ATryn in Europe, we believe we established a strong regulatory basis for our transgenic manufacturing platform, which encourages us to move forward with confidence with ATryn both in Europe and the United States," said Geoffrey Cox, GTC’s chairman and CEO, while delivering his company’s 2005 results March 6. He said he expected the appeal process in Europe to be concluded mid-year.

According to an explanatory statement from the agency for the proposed indication, "only five surgical cases were considered. The CHMP considered this number to be too small." It added that the company had been advised earlier in the application process that it should present data on 12 patients.

"ATryn was studied in 14 patients with congenital antithrombin deficiency at risk of a thromboembolic event (surgery [five patients] or childbirth [nine patients]). The company also presented the results of the treatment in five patients who received the medicine during surgery in a compassionate-use program," the statement said, but "the results in patients treated in the compassionate-use program and at childbirth could not be used to support the proposed use in patients undergoing surgery."

The agency also had concerns over the production process of the medicine used in the studies, which had an additional filtration step not envisaged for the product to be marketed. The product is extracted from the milk of goats with an inserted gene that enables them to produce the human antithrombin protein. "ATryn is a protein-based medicine, and, like all protein-based medicines, it is possible that patients develop antibodies," it said. "The CHMP considered that the company did not carry out enough studies looking for the development of antibodies."

Second Biosimilar Wins Support In EU

BioPartners GmbH’s Valtropin became the second biosimilar to receive a favorable opinion from the European Medicines Agency at the February meeting of its expert committee. Valtropin is similar to Indianapolis-based Eli Lilly and Co.’s Humatrope, the reference medicinal product already authorized in the EU. Zug, Switzerland-based Biopartners’ version is indicated for the treatment of growth disturbance and growth-hormone deficiency. The opinion still requires endorsement from the European Commission within 90 days, but that usually is a formality. In January, the agency gave its first positive opinion on a biological similar, Omnitrope, from Novartis AG unit Sandoz, which is a copy of Pfizer Inc.’s Genotropin, already authorized in the EU. The agency started its review of Valtropin in July 2004. Sandoz is located in Holzkirchen, Germany.

Sanofi’s Hepatitis B Vaccine Under Scrutiny

Two biotech-derived vaccines from Sanofi Pasteur MSD have been put under review by the European Medicines Agency. The review is intended to assess the efficacy of HBVAXPRO (recombinant hepatitis B virus small surface antigen [HBsAg]) and Procomvax (haemophilus influenzae b conjugate and hepatitis B [recombinant] vaccine). The two products share the same recombinant hepatitis B component as Hexavac, from the same company, whose marketing authorization was suspended last September over concerns about long-term protection against hepatitis B. The agency said it now will review all data to determine whether similar concerns also would apply to HBVAXPRO and Procomvax.

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