March 24, 2004

News Release: Adherex Receives FDA Orphan Drug Designation for STS: Designation Provides Seven Year Market Exclusivity Following Approval

Adherex Technologies Inc. (TSX: AHX), a biopharmaceutical company with a broad portfolio of products under development, today announced that is has received orphan drug designation for sodium thiosulfate (STS) from the U.S. Food and Drug Administration (FDA). The designation was granted for the prevention of platinum-induced ototoxicity in pediatric patients.

'FDA orphan drug designation for STS is a major milestone for both children with cancer and for the Company,'said Dr. William P. Peters, CEO and Chairman of Adherex. 'Hearing loss among children receiving platinum-based chemotherapy is frequent, permanent and severely disabling and affects nearly a third of all children with cancer. Orphan drug designation for STS makes development commercially viable and provides multiple incentives for Adherex to undertake further clinical trials to potentially solve this significant clinical problem.' The FDA orphan-drug designation, administered by the Office of Orphan Products Development, encourages companies to develop treatments for diseases that affect fewer than 200,000 patients, or, as in this case, for preventative drugs that will be administered to fewer than 200,000 patients per year. The designation provides potential incentives such as funding for clinical studies, study design assistance, waiver of FDA user fees, substantial tax credits and, most importantly, up to seven years of market exclusivity upon regulatory approval.

STS is currently FDA approved for use in humans as part of a treatment for cyanide poisoning. Adherex obtained the intellectual property rights directed to the use of this compound as a chemoprotectant, including protection against hearing loss, through a licensing agreement with Oregon Health &Science University (OHSU). Pre-clinical investigations using animal ototoxicity models have demonstrated that STS is an effective otoprotective agent with platinum administration. Two clinical Phase I and Phase II studies have been completed by OHSU and confirm the efficacy and safety of STS as an otoprotectant for platinum-induced ototoxicity.

Dr. Edward Neuwelt of OHSU said, 'Our data thus far has shown protection against platinum-induced hearing loss not only in animal models but also in human Phase I and Phase II clinical studies involving more than 100 patients. The need for hearing aids to correct high frequency hearing loss in these patients was reduced from about 50% to less than 5%. There is major interest in conducting a prospective, randomized trial using the Adherex drug, which would serve as a potential drug registration trial for this important clinical problem.'

About Adherex Technologies

Adherex Technologies Inc. is a biopharmaceutical company with a broad portfolio of products under development. Four products are in clinical development including Exherin(TM), Adherex's lead cadherin antagonist compound, and STS, a drug that protects against severe hearing loss that is often produced by platinum-based anticancer agents. Adherex's intellectual property includes broad, interlocking protection for cadherin-mediated adhesion and represents what the Company believes to be the world's broadest portfolio of vascular targeting and cell adhesion modulating agents. The Company has offices in Research Triangle Park, North Carolina and Ottawa, Canada.

For more information, please visit Adherex's website at www.adherex.com.

Dr. Neuwelt and the Oregon Health &Science University have significant financial interests in Adherex, a company that has a commercial interest in the results of this research and technology. This potential conflict of interest has been reviewed and managed by the OHSU Conflict of Interest in Research Committee.

This news release shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

Certain information contained in this news release is forward-looking and is subject to unknown risks and uncertainties. The actual results, performance or achievements of the Company may differ materially from the results, performance or achievements of the Company expressed or implied by such forward-looking statements.

NATIONAL ir Peter Block (Media Contact) (416) 586-0180 This email address is being protected from spambots. You need JavaScript enabled to view it. or Adherex Technologies Inc. Nickola Capstick (Investor Contact) (613) 738-8000, ext. 293 This email address is being protected from spambots. You need JavaScript enabled to view it.

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