BioWorld International Correspondent

Intercell AG gained further validation for its proprietary Antigen Identification Program (AIP) in the shape of Merck & Co. Inc., which has converted a pre-existing option into a strategic partnership to develop monoclonal antibodies against severe infections caused by Staphylococcus aureus.

Terms were not disclosed, but Vienna, Austria-based Intercell receives an option exercise fee, and could get milestones and royalties. The aim is to develop products that would augment or complement antibiotic therapy.

"The pipeline of new antibiotics coming to the market is anything but full," Intercell Co-Founder and Chief Scientific Officer Alexander von Gabain told BioWorld International. "You will have a very selective use of these antibacterial agents."

The deal is additional to a previous agreement between the companies to develop a vaccine against the same pathogen, also based on Intercell's AIP platform. "It is primarily aiming at the same antigen," von Gabain said. The Merck vaccine recently entered a Phase I trial.

Intercell now has signed four deals based on its antigen identification platform. Last month, it entered a similar antibody development agreement, involving Streptococcus pneumoniae, with Tokyo-based Kirin Brewery Co. Ltd. That deal, which included an up-front payment of €4 million (US$5.1 million), could be worth up to €40 million in total payments, plus royalties on product sales. In addition, Paris-based Sanofi-Aventis Group is developing a vaccine against an undisclosed pathogen, again based on Intercell's AIP technology.

The technology is based on exposing labeled antibodies, isolated from individuals who are either resistant to or have recovered from infections with the target organism, to epitope libraries generated by expressing peptide fragments on the surface of E. coli cells.

"We chop up the genome of the pathogen in random small insert libraries," von Gabain said. Linear and larger, 3-dimensional epitopes can be expressed in that fashion. Paramagnetic beads can be used to recover antibody-cell complexes for further analysis.

Typically, that approach yields 100 to 150 unique antigenic proteins per pathogen, von Gabain said. Intercell then narrows the field by pursuing antigens that are highly conserved and common to all important clinical isolates. It selects 10 to 15 for animal work, which allows it to narrow the search for validated antigens further.

"We also select antigens that have a vital function for bacterial survival in the body," von Gabain said.

The company has completed that process for more than a dozen pathogens. It will develop the work further both in-house and through partnerships. It plans to develop a vaccine in-house against S. pneumoniae to overcome the shortcomings of existing conjugate vaccines marketed by Merck, of Whitehouse Station, N.J., and Wyeth, of Madison, N.J. Although both products are commercially successful, von Gabain said, Merck's Pneumovax targets only 23 serotypes, and Wyeth's pediatric vaccine Prevnar protects against seven serotypes. "You have more than 90 glycosidic serotypes in the community," he said.

The company's lead product, a vaccine against Japanese encephalitis virus, is undergoing a pivotal Phase III trial. Preliminary efficacy data will become available in the next six to eight weeks, von Galbain said. The company aims to initiate its U.S. regulatory filing for the product before the year's end.