( -- 46% of Evaluable Patients Show Stabi...)Avalon Pharmaceuticals Announces Positive Interim Results For,AVN944 Phase I Trial,Health

GERMANTOWN, Md., June 19, 2007 /PRNewswire-FirstCall/ -- Avalon Pharmaceuticals, Inc. , today announced continued positive interim results from its Phase I study of AVN944, for the treatment of hematologic malignancies in elderly and refractory patients. Interim data indicate AVN944 is well tolerated, has dose-dependent pharmacokinetics, induces biomarkers of programmed cell death in cancer cells from patients, and demonstrates stabilized disease in almost half of the patients after one-month of treatment.

"We continue to be encouraged by the positive interim results from the AVN944 trial," stated Michael Hamilton, M.D., Avalon Pharmaceuticals' Chief Medical Officer. "We have observed important indications of biological drug effect and disease stabilization in a significant number of patients. We continue to believe the Phase I trial will provide sufficient information to initiate multiple Phase II studies."

Background: AVN944 is an oral small molecule drug that inhibits inosine monosphospate dehydrogenase (IMPDH), a critical enzyme for synthesis of guanosine triphosphate (GTP), a molecule required for DNA synthesis and cellular signaling. IMPDH is over expressed in many cancer cells. Pre-clinical studies showed that AVN944 is a highly specific inhibitor of IMPDH, suppresses pools of GTP, and in cultured cells has a selective growth inhibition effect on cancer cells vs. normal cells.

An earlier single-dose, dose-escalation, healthy volunteer clinical trial conducted in the United Kingdom showed that AVN944 was well tolerated at all tested doses with no notable side effects; had good pharmacokinetic properties; and had a significant inhibitory effect on IMPDH enzyme activity.

Study Design: The current U.S. Phase I study is a repeat-dos
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