BioWorld International Correspondent

Crucell NV, of Leiden, the Netherlands, unveiled a new genetic vaccination system called AdVac at the 4th annual meeting of the American Society of Gene Therapy in Seattle on June 1.

The new gene delivery system is based on the serotype 35 adenovirus vector, and the data presented by Crucell indicate that it binds to, and efficiently traduces, human cells that elicit a strong immune response.

Moreover, the AdVac vector is not inactivated by the anti-adenovirus antibodies present in most individuals, unlike current systems derived from human adenovirus serotype 5, a common human cold virus, which are rapidly rendered ineffective by the activity of the recipient's antibodies.

Finally, Crucell says that its system does not infect liver cells, whereas hepatotoxicity is a characteristic unwanted side effect of currently used vectors.

The Dutch company says that vaccines using AdVac will generate strong immune responses at doses equivalent to only 1 percent of existing systems, improving safety as well as efficacy.

AnneMarie Haverhals, Crucell's vice president of corporate affairs, told BioWorld International that the technology would be valid for any vaccines against diseases characterized by the presence of antigens. The company plans to carry out further tests of AdVac to validate the technology fully before deciding how best to exploit it. It could well develop vaccines based on itself, as well as licensing it out to other biopharmaceutical companies. "Anything can happen," Haverhals said.

Third parties already are developing new vaccines using Crucell technology. In April, Merck & Co. embarked on a Phase I clinical trial of an HIV vaccine using a modified adenovirus vector grown on Crucell's PER.C6 cell line. (See BioWorld International, April 11, 2001.)

An agreement signed between the two companies in October 2000 granted Merck an exclusive license to use the PER.C6 platform for developing vaccines for the prevention and treatment of certain diseases.

In other news from the American Society of Gene Therapy meeting:

  • Chromos Molecular Systems Inc., of Burnaby, British Columbia, presented data on the development of its chromosome-based platform technology for gene therapy. Chromos said the platform technology can be used for stable delivery and expression of a wide range of large genes or multiple gene targets.

  • Targeted Genetics Corp., of Seattle, presented data from a repeat-dosing study of aerosolized tgAAVCF in nonhuman primates. The product is being co-developed with Celltech Group plc, of Slough, UK. The data demonstrated a dose-dependent gene transfer, detectable gene expression in five of eight vector-treated animals, a limited extra-pulmonary biodistribution pattern with no distribution to the gonads and sustained levels of vector over multiple doses. A Phase II repeat-dosing study of aerosolized tgAAVCF in patients with cystic fibrosis is ongoing, and more than 70 patients have received it to date.

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