PRESS RELEASE: Astellas to Acquire Agensys

Astellas to Acquire Agensys

Japan, November 27, 2007 - Astellas Pharma Inc. (“Astellas”; headquarters: Tokyo; President and CEO: Masafumi Nogimori) today announced that its US subsidiary, Astellas US Holding, Inc. (headquarters: Deerfield, IL) has signed a definitive agreement on November 26, 2007 (US time), to acquire Agensys, Inc. (“Agensys”; headquarters: Santa Monica, CA; Chairman, President & CEO: Donald B. Rice, Ph.D.) for $387 million up front assuming approximately $30 million net cash balance at closing.  In addition, Agensys’ current shareholders will retain the right to receive a maximum of $150 million in accordance with Agensys’ achievement of various milestones.

Agensys is a biotechnology company specialized in therapeutic antibody research and development in cancer.  It has selected candidate targets by applying differential gene expression technology to human tissues and identified 30 proprietary targets in 14 cancer types.  It has rich experience in using its optimized hybridoma method* to generate fully human monoclonal antibodies, including to challenging targets, from XenoMouse® a human antibody-producing transgenic mouse in-licensed from Abgenix (currently a part of Amgen).  It also has GMP manufacturing facilities producing investigational antibodies for pre-clinical and early-stage clinical studies.  Agensys’ pipeline includes an antibody in a Phase Ib clinical trial and several candidate antibodies in late preclinical stage.

Mr. Nogimori said, “Astellas will continue to build our company into a strong, global pharmaceutical leader.  Agensys will be the cornerstone of our biologics efforts and an integral component of building our oncology efforts within our franchise.  We welcome Agensys employees to the Astellas family.”

Astellas, in its medium-term plan, has declared that it will aggressively build up its antibody R&D capabilities.  Astellas acquired a non-exclusive license to Regeneron’s VelocImmune® Technology and an access to phage display library from MorphoSys both in March 2007.  It further reinforced its basis of antibody research through establishment of Advanced Biologics Section in Molecular Medicines Research Laboratories this October.  Astellas believes that this acquisition of Agensys will provide Astellas access to expertise and assets in fully human monoclonal antibody technologies, proprietary target molecules in the cancer field, and clinical candidate antibody pipeline.  The combined company will reinforce and accelerate Astellas’ antibody R&D in cancer, one of the important research therapeutic areas.  Target molecules proprietary to Agensys are also expected to contribute to Astellas’ in-house small molecule oncology drug discovery.

Dr. Rice said, “This transaction represents a rare combination of a deal that is a win for our investors, for Astellas, and for Agensys employees.  It is a real tribute to the accomplishments of the Agensys team.  We were attracted by Astellas’ desire to build on the core Agensys team to accelerate our discovery and commercial efforts, while working together to achieve our shared vision of building a global leader in biologics and oncology.”

The pharmaceutical market in cancer treatment was approximately \1.7 trillion as of 2005 and is expected to double to approximately \3.4 trillion by 2015.  Among these, new treatments such as antibodies, molecular targeted drugs and nucleic acid agents will expand rapidly and are anticipated to represent half of the market.

Upon completion of the transaction, a newly established subsidiary of Astellas US Holding, Inc. shall be merged with and into Agensys and Agensys shall become a wholly owned subsidiary of Astellas US Holding, Inc.  The closing of the transaction is subject to Agensys shareholder and customary regulatory approvals, but is expected to take place by the end of December 2007.  Montgomery & Co. LLC is acting as financial advisor and Morrison & Foerster LLP is acting as legal counsel to Astellas in this transaction.  J.P. Morgan Securities Inc. is acting as financial advisor and Latham & Watkins LLP is acting as legal counsel to Agensys in this transaction.

*Hybridoma method

Method to generate monoclonal antibodies by hybridoma, which is derived by cell fusion of an antibody producing B cell and myeloma cell.

About Agensys

Profile

Agensys is a private biotechnology company located in Santa Monica, CA.  It began operations in 1997 as UroGenesys, founded by oncologists at UCLA and Dr. Rice, joined by Dr. Jakobovits, an inventor of XenoMouse® at Abgenix, in 1999 as CSO.  The company changed its corporate name to Agensys in 2001.  There are approximately 100 employees.  Agensys discovers proprietary targets using tumor tissues derived from patients and has already identified 30 proprietary targets in 14 cancer types.  It has expanded its oncology research focus from urology to a broad range of cancers and also its business from target discovery to antibody product development, manufacturing, and clinical trials.  Agensys’ pipeline includes therapeutic naked antibodies and antibody drug conjugates.  It licenses out targets and antibody products in early stage clinical development, and is jointly developing them with partners, while retaining a robust pipeline for its own account.

Technology

·    Identification of cancer target molecules

System of high-quality target molecule identification has been established.  Bank of high-quality patient-derived tumor and healthy tissues has been constructed in-house, obtained from multiple suppliers.  Following selection of candidate targets through differential gene expression profiling of tumor tissues from different disease stages and healthy tissues, it is verified via immunohistochemical staining using tissue arrays, in vitro / in vivo functional analysis using siRNA, antibody and other reagents.

·    Xenograft model using tumor tissues derived from patients

Xenograft models using tumor tissues derived from patients have been established for multiple major cancer types.  The models are used to evaluate drugs for targets highly expressed in tumor tissues derived from patients but having no or limited expression in established tumor cell lines.  They also better represent clinical conditions  of the human cancers.  Regarding prostate cancer, it is protected by patents in the US and Europe, and Agensys holds an exclusive license.

·    Fully human monoclonal antibody technology

High affinity monoclonal antibodies are routinely generated from XenoMice in-licensed from Abgenix (currently a part of Amgen) using hybridoma methods optimized by Agensys. High-throughput screening is adapted to hybridoma screening.

·    Antibody drug conjugate technology

Agensys has licensed Seattle Genetics’ proprietary linker-toxin technology, licensed from Seattle Genetics, for development of therapeutic antibody drug conjugates.

·    Antibody production

Facility including cell culture instruments and purification instruments in accordance with GMP is available.  Its MAb manufacturing capability is enough to cover clinical trial material supply for Phase I trials and early Phase II trials.