Adherex Activates Phase I Trial of Eniluracil.

RESEARCH TRIANGLE PARK, N.C. -- Adherex Technologies Inc. (TSX:AHX)(AMEX:ADH), a biopharmaceutical company with a broad portfolio of oncology products under development, today announced the activation of a Phase I clinical trial of the combination of eniluracil and 5-fluorouracil (5-FU). This study follows Adherex's announcement in late November 2005 that the U.S. Food and Drug Administration (FDA) had cleared its Investigational New Drug (IND) application for eniluracil.

"We are looking forward to studying eniluracil in clinical trials," said Howard Burris, MD, Director of Drug Development, Sarah Cannon Cancer Center, Nashville, Tennessee. "Eniluracil had shown promise in early trials, and this new dose and schedule strategy may allow improvement of the effectiveness and side effect profile of 5-FU."

This Phase I dose escalation study will enroll patients with solid tumors and is intended to define the maximum tolerated dose of weekly dosing of the combination of eniluracil and 5-FU. Adherex expects the study to complete in the third quarter 2006 and then plans to initiate a Phase II trial in breast cancer.

In November 2005, Adherex announced its global development plans for eniluracil. These plans include three preliminary studies to define the optimal dose of eniluracil, the optimal dose ratio and schedule of eniluracil in combination with 5-FU, and the clinical response rate to Adherex's proprietary combination of the two drugs. The first of these studies is the Phase I study announced above. A second Phase I study, expected to begin shortly, will investigate the specific effects of eniluracil on the enzymatic pathways of 5-FU metabolism in patients with colorectal cancer who undergo surgery to remove their tumors. The third study, a Phase I/II clinical trial in liver cancer, is expected to begin in the second quarter 2006 in Asia.

In December 2005, the Company received orphan drug designation for the use of eniluracil in combination with fluoropyrimidines (including 5-FU) for the treatment of hepatocellular cancer. The Company expects a Phase III trial of the combination of eniluracil and 5-FU in hepatocellular cancer could begin by mid 2007.

"Eniluracil represents a considerable therapeutic and commercial opportunity for Adherex. It has the potential to make a mainstay of contemporary cancer therapy, 5-FU, even better, and could have a market opportunity in excess of a billion dollars," said William P. Peters, MD, PhD, Chairman and CEO of Adherex. "Importantly, since eniluracil has already been extensively studied by GlaxoSmithKline in more than 1500 patients, we expect to be able to shorten the development timelines and initiate Phase III trials by mid 2007. This Phase I trial, which is intended to demonstrate the safety of our proprietary combination, should take only six to eight months to complete."

Adherex is developing eniluracil, which it in-licensed from GlaxoSmithKline in July 2005, to improve the therapeutic value and effectiveness of 5-FU, one of the world's most commonly used anti-cancer drugs. Adherex has preclinical data which indicate that when eniluracil and 5-FU are combined in the proper dose, dose ratio and schedule, the combination can be more effective and less toxic than 5-FU or similar 5-FU prodrugs alone. Although 5-FU is a mainstay of contemporary cancer therapy, it has some therapeutic drawbacks. These include that it must be given intravenously, it can cause severe and often dose-limiting side effects, and it has variable blood and tissue levels which can impact its anti-tumor activity and safety profile. In combination with eniluracil, 5-FU is orally active and has more uniform and prolonged blood and tissue levels, thereby potentially improving its side effect profile and anti-tumor effects.

About Adherex Technologies

Adherex Technologies Inc. is a biopharmaceutical company dedicated to the discovery and development of novel cancer therapeutics. We aim to be a leader in developing innovative treatments that address important unmet medical needs in cancer. We currently have multiple products in the clinical stage of development, including ADH-1 (Exherin(TM)), eniluracil and sodium thiosulfate (STS). ADH-1, our lead biotechnology compound, selectively targets N-cadherin, a protein present on certain tumor cells and established blood vessels that feed solid tumors. Eniluracil, an oral dihydropyrimidine dehydrogenase (DPD) inhibitor, was previously under development by GlaxoSmithKline for oncology indications. STS, a drug from our specialty pharmaceuticals pipeline, protects against the disabling hearing loss that can often result from treatment with platinum-based chemotherapy drugs. With a diversified portfolio of unique preclinical and clinical-stage cancer compounds and a management team with expertise in identifying, developing and commercializing novel cancer therapeutics, Adherex is emerging as a pioneering oncology company. For more information, please visit our website at www.adherex.com.

This press release contains forward-looking statements that involve significant risks and uncertainties. The actual results, performance or achievements of the Company might differ materially from the results, performance or achievements of the Company expressed or implied by such forward-looking statements. Such forward-looking statements include, without limitation, those regarding the development plans of the Company and the expected timing and results of such development. We can provide no assurance that such development will proceed as currently anticipated or that the expected timing or results of such development will be realized. We are subject to various risks, including those inherent in the biopharmaceutical industry, the early stage of our product candidates, the uncertainties of drug development, clinical trials and regulatory review, our reliance on collaborative partners, our need for additional capital to fund our operations, and our history of losses. For a more detailed discussion of related risk factors, please refer to our public filings available at www.sedar.com and www.sec.gov.

Adherex Technologies Inc. (TSX:AHX) (AMEX:ADH)