Xerion Pharmaceuticals and Xoma sign licensing agreement

Martinsried, Germany and Cambridge, MA, USA - August 13, 2003 –  Xerion Pharmaceuticals announced today that it has entered into a license agreement with XOMA Ireland Limited related to its bacterial expression technology.

Under the agreement Xerion receives rights to use the XOMA antibody expression technology for developing antibody products derived from phage display libraries for itself and Xerion collaborators. Xerion also has an option to license the production of antibodies under the XOMA patents. XOMA will receive license and royalty payments from Xerion. In addition, Xerion and XOMA have a co-development and commercialization option on antibody products generated by Xerion.

“We are pleased to have access to XOMA’s bacterial antibody expression technology that can be used for internal as well as our present and future collaborator projects,” said Markus Ewert, Ph.D., CEO and President of Xerion Pharmaceuticals. “As we move toward a product-focused company, we are very satisfied to have this agreement in place that provides us with development and manufacture options.”

About Xerion Pharmaceuticals

Xerion Pharmaceuticals is building a pipeline of novel therapeutic targets and antibodies. To identify targets, the Company uniquely focuses on proteins, using proprietary technologies to selectively block their function in diseased cells thereby mimicking the activity of a drug. Xerion integrates this approach with the ability to rapidly generate therapeutic antibody leads. The Company is developing these targets and antibodies independently and in conjunction with partners with an initial emphasis on cancer. For additional information, please visit our Website at www.xerion-pharma.com.

Xerion is headquartered in Martinsried, Germany and its subsidiary Xerion Pharmaceuticals Inc. is based in Cambridge, MA, U.S.A. The Company has license and collaborative agreements with Altana Pharma AG, Arius Research Inc., Cambridge Antibody Technology Ltd., Procorde GmbH, and several research institutes.

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