ARTEMIS and Haptogen Enter Scientific Collaboration
Joint development of novel in vivo models for preclinical evaluation of therapeutic antibodies

Aberdeen, UK and Cologne, Germany, 31st October 2006 Haptogen Ltd, the antibody developer and ARTEMIS Pharmaceuticals GmbH today announced a new joint collaboration to develop and validate novel genetically modified mouse models to test immunogenicity of compounds in preclinical studies.

The mice will be used as in vivo models for human biology by replacing certain mouse genes with their human counterparts. The models will be designed to improve preclinical evaluation of human and humanized therapeutic proteins. This alliance combines ARTEMIS' leading platform in mouse genetics and genomics with Haptogen's leading expertise in the generation and development of therapeutic antibodies.

Protein drugs - biologicals - and in particular human and humanized monoclonal antibodies (MAbs) have enormous potential as novel drugs for the treatment of severe human diseases. However, a major challenge remains the availability of preclinical in vivo models able to predict more accurately potential adverse effects due to immunogenicity.

To contribute to solving this problem, ARTEMIS and Haptogen aim to provide humanized transgenic mouse lines able to mimic human immuno responses. To achieve this goal ARTEMIS will use its ArteMice™ technologies to generate genetically engineered mouse models in which selected genes of the immune system of the mouse are replaced by their human counterparts. Haptogen will validate the models using its Haptomics® generated antibodies.

"A recognized limitation with in vivo testing today is the immunogenicity of human and humanized MAbs on repeat dosing in clinical models and the difficulty of interpreting the data," said Jim Reid, CEO of Haptogen. "One way of overcoming this is to generate murine versions of the MAbs but this is time consuming."

ARTEMIS will commercialize the models through its established sales and marketing organisation and Haptogen will use the models in its preclinical trials for infectious, renal and metabolic compounds.

"These new models have the potential to significantly improve the way in which new therapeutic antibodies and proteins are tested, increasing both the efficiency and efficacy of this process," commented Paul Rounding, Managing Director of ARTEMIS.

"They fit closely with ARTEMIS' strategy to develop and broadly commercialize a wide range of in vivo tools and products designed to increase the efficiency of drug discovery," Rounding noted.

About Haptogen Haptogen, founded in 2002, focuses on drug discovery and development of therapeutic antibodies that bind haptens (eg hormones and cell signalling molecules) and haptenic structures (defined protein epitopes, glycosylation and phosphorylation states). This approach enables Haptogen to reach previously non-accessible targets.

Haptogen's in-house clinical focus is in infectious, renal and metabolic diseases. The company applies its SmartTargets™ strategy, based on the propriety Haptomics( platform technology, to select low-risk targets for its own product pipeline but also against partner targets. In addition to therapeutic applications the technology has been applied to clinical, biochip and environmental diagnostics.

Haptogen is building value by developing orphan indication compounds for in- house development and partnering these compounds to addresst unmet medical needs. The company is led by a highly experienced commercially minded management team backed up with internationally recognised academic and scientific expertise.

In 2005, Haptogen's CEO, Jim Reid and CSO, Andy Porter, were awarded the prestigious Ernst and Young PLC Entrepreneur of the Year for Science and Technology in the UK and Deloitte named Haptogen as a "Rising Star" in the technology awards for the UK's fastest growing high-technology companies. www.haptogen.com

About ARTEMIS

ARTEMIS Pharmaceuticals has developed the worldwide leading portfolio of scientific and technological tools in murine molecular genetics and functional genomics. It offers custom-made genetically engineered mouse models for use at various stages of the industrial drug discovery process or for academic research.

ARTEMIS has formed a strategic alliance with Taconic, one of the world's leading breeders of laboratory rodents. This alliance enables the generation and delivery of genetically modified in vivo models to customers with unprecedented speed and quality.

ARTEMIS customers include the majority of the leading pharmaceutical companies including Merck, Inc., Sanofi-Aventis, Bayer AG, Boehringer Ingelheim, Astra Zeneca, Glaxo Smith Kline, Schering AG, Bristol-Myers Squibb, Lilly, Merck KGaA, Biovitrum AB, other pharma companies and biotech firms as well as various academic Research Institutions worldwide.

ARTEMIS is a wholly owned subsidiary of Exelixis, Inc., South San Francisco, CA. USA (Nasdaq:EXEL) since 2001.

For further information please contact

ARTEMIS
Monika Hahn
Tel: +49(0)221-96453-10

Haptogen
Fiona Adair
Tel: +44 (0)1224 555889
fiona.adair@haptogen.com

Capital MS&L
Mary Clark or Halina Kukula, Capital MS&L
Tel: +44 (0)20 7307 5330
shaun.brown@capitalmsl.com