Viventia Biotech Inc. Reports Final Vicinium(TM) Phase I/II Bladder Cancer Data at the American Urological Association Annual Meeting

TORONTO, May 24 /PRNewswire/ - Viventia Biotech Inc., a privately held biopharmaceutical company advancing a portfolio of novel antibody products focused on cancer, today reported final data from its recently completed dose escalation Phase I/II clinical trial of Vicinium(TM) in patients with high risk, non-invasive bladder cancer. The results were presented at the 102nd Annual Meeting of the American Urological Association, which runs from May 19-24, 2007 in Anaheim, California. Vicinium(TM) is a fusion protein comprised of a humanized antibody fragment specific for the antigen EpCAM, conjugated to a cytotoxic protein, Pseudomonas exotoxin A.

The trial enrolled 64 patients who were refractory or intolerant to standard treatment (BCG therapy). Patients were dosed on a weekly basis for 6 weeks at escalating dose levels using intravesical instillation. Although designed as a phase I study, an efficacy analysis demonstrated that only 7% of these high risk patients progressed during the study period. Vicinium(TM) was very well tolerated at all dose levels with no maximum tolerated dose reached and no patient had a dose reduction or withdrawal due to toxicity.

“Patients with non-invasive bladder cancer, which comprise the majority of bladder cancers, that progress after failing conventional treatments usually require complete removal of the bladder to prevent further disease progression and avoid metastasis to other organs. Vicinium(TM), which was well-tolerated and provided an overall 93% disease control rate in a very high risk population, has the potential to someday substantially delay or eliminate the need for these more drastic options,” said Dr. Nick Glover, President and CEO of Viventia Biotech. “Moreover, Vicinium(TM) has demonstrated an early safety profile far more favorable than the established therapies.”

Patients were also monitored for duration of response following the completion of the protocol. Ongoing post hoc analyses demonstrated a sustainable response lasting more than 6 months in most of these patients, with many patients still disease free out to 12 months. Sustainability of response is being specifically assessed in an ongoing open-label Phase II trial of Vicinium(TM), which is currently enrolling patients with locally persistent non-invasive Cis bladder cancer in Canada and the U.S. Further details on Vicinium(TM) and this clinical trial are available at www.vicinium.com.

These data were presented by Dr. Michael Jewett, the principal investigator on the trial. Dr. Jewett is a Professor of Surgery (Urology) at the University of Toronto, a member of the Department of Surgical Oncology of Princess Margaret Hospital and a clinician investigator at the University Health Network. From 1991 to 2002, Dr. Jewett was the Chairman of the Division of Urology at the University of Toronto and Head of Urology at the University Health Network, which incorporates Princess Margaret Hospital. Preliminary results from this trial were presented at the 2006 ASCO meeting.

Viventia’s lead product, Proxinium(TM), is being developed to treat late stage, locally advanced head and neck cancer and is currently enrolling patients in its TARGET trial, a pivotal Phase III global clinical trial that is also expected to complete accrual by the end of 2007. Vicinium(TM) and Proxinium(TM) are Armed Antibodies(TM) that target the cancer antigen EpCAM.

Viventia Biotech retains full global product rights to Proxinium(TM) and Vicinium(TM). The Company is seeking partners for Proxinium(TM) and Vicinium(TM) capable of complementing Viventia’s development expertise with their global sales, marketing and commercial capabilities.

About bladder cancer

Bladder cancer is the 5th most common cancer in North America. Approximately 60,000 new cases are diagnosed each year, with an estimated 15,000 deaths attributed to the disease annually. The incidence rate of bladder cancer has risen by more than 35% in the past decade and its prevalence in the U.S. population is at least 400,000 cases. Cis is a particularly aggressive form of the disease. In Cis, involvement of the urothelium ranges from a small focus to extensive disease throughout the bladder. The risk of progression to muscle invasive disease and subsequent metastases ranges from 40 to 80% with Cis, depending on the extent of disease. Standard treatment is cystectomy. Cis does not respond reliably to the most common forms of local therapy, BCG or chemotherapy. For many patients, Cis bladder cancer persists following initial treatment and they ultimately may require complete or partial removal of the bladder. There are currently limited therapeutic options for patients failing first line therapy for persistent disease.

About Viventia Biotech:

Viventia Biotech Inc. is a privately held biopharmaceutical company generating a pipeline of fully human antibodies and identifying novel targets for the treatment of cancer. Its lead products have been further developed into Armed Antibodies(TM): powerful and precise anti-cancer drugs that combine cytotoxic protein payloads with the highly precise tumor-targeting characteristics of monoclonal antibodies to overcome various forms of cancer. Viventia’s lead product, Proxinium(TM), is undergoing a global Phase III clinical trial - TARGET - for the treatment of head and neck cancer. Viventia is also developing Vicinium(TM), which is in a Phase II clinical study for the treatment of bladder cancer, and VB6-845, beginning a Phase I/II clinical trial for the treatment of solid tumors. The Company has created a portfolio of follow-on fully human antibody drug candidates and has a discovery engine to provide a rich and sustainable long-term pipeline.

Viventia Biotech Inc.

CONTACT: James Smith, Tel. (416) 815-0700 x 229, Fax. (416) 815-0080,Email: jsmith@viventia.com; www.viventia.com; www.vicinium.com

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