News Release

Avalon Pharmaceuticals names lead development candidate in beta-catenin inhibitor program

Business Announcement

Dorland Global Public Relations

Germantown, MD, June 26, 2008 -- Avalon Pharmaceuticals, Inc. (Nasdaq: AVRX), announced today the nomination of AVN316 as a lead clinical development candidate in its Beta-catenin Pathway Inhibitor program. This novel compound inhibits the Beta-catenin pathway and is a potent inducer of cancer cell death. The Company plans to begin clinical testing of AVN316 in patients in 2009.

Beta-catenin is one of the most commonly activated cancer pathways and is known to play a key role in the initiation and progression of cancer. The Beta-catenin pathway is upregulated in a large number of different cancer types, in particular colon cancer, where it has been estimated to be abnormally activated in at least 90 percent of cases.

"The biological complexity and the classically intractable nature of the beta-catenin protein have prevented this pathway from being effectively targeted by conventional drug discovery techniques, despite the efforts of numerous pharmaceutical companies," stated Kenneth Carter, Ph.D., President and CEO of Avalon Pharmaceuticals, Inc. "We are very pleased to name AVN316 as the lead compound for this intractable target, which we believe provides validation for our unique drug discovery platform, AvalonRx®."

Using AvalonRx®, the Company identified several chemical compounds series that inhibit beta-catenin function. One family of structurally distinct chemical compounds potently down-regulate the Beta-catenin pathway by reducing beta-catenin protein levels. This lead compound series (of which AVN316 is a member) decreases the beta-catenin protein levels in cancer cells and xenograft tumors, induces biomarkers of Beta-catenin pathway inhibition, and inhibits tumor growth. AVN316 was chosen from the series for its potency and tumor growth inhibition properties in animal models of human disease. Near-term activities with AVN316 include toxicology studies and large-scale manufacturing in preparation for IND submission to the FDA.

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About Avalon Pharmaceuticals

Avalon is a biopharmaceutical company focused on the discovery, development and commercialization of first-in-class cancer therapeutics. Avalon's lead product candidate, AVN944, an IMPDH inhibitor, is in Phase II clinical development. Avalon also has preclinical programs to develop inhibitors of the Beta-catenin and Aurora/Centrosome pathways, discovery programs for inhibitors of the Survivin and Myc pathways and partnerships with Merck, MedImmune, ChemDiv, Medarex, and Novartis. AvalonRx® is the company's proprietary platform which is based on large-scale biomarker identification and monitoring, used to discover and develop therapeutics for pathways that have historically been characterized as "undruggable." Avalon is headquartered in Germantown, MD.

About AvalonRx®

AvalonRx® is a comprehensive, innovative and proprietary suite of technologies based upon large-scale gene expression analysis. This platform facilitates drug discovery by expanding the range of therapeutic targets for drug intervention, including targets and target pathways frequently considered intractable using conventional HTS approaches, allows more informed decisions about which compounds to advance towards clinical trials, and facilitates drug development through identification of biomarkers of efficacy that can stratify patients or provide early indicators of response.

Safe Harbor Statement

This announcement contains, in addition to historical information, certain forward-looking statements that involve risks and uncertainties including Avalon's plans to conduct toxicology studies and large scale manufacturing of AVN316 in preparation for an IND filing with the FDA. Such statements reflect the current views of Avalon management and are based on certain assumptions. Actual results could differ materially from those currently anticipated as a result of a number of factors, risks and uncertainties, including those specified under the "Risk Factors" section of our 2007 Annual Report on Form 10-K and updates contained in subsequent filings we make with the Securities and Exchange Commission.

Contacts:

Avalon Pharmaceuticals, Inc.
C. Eric Winzer
Executive Vice President & Chief Financial Officer
Tel: (301) 556-9900
Fax: (301) 556-9910
Email: info@avalonrx.com

Dorland Global Public Relations
Kate Gormley (Media)
Tel: (215) 928-2720
kgormley@dorland.com

The Trout Group
Chad Rubin (Investors)
Tel: (646) 378-2947


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