• 5/17/2005
  • Toronto, Ontario, Canada
  • press release
  • Newswire Canada (www.newsire.ca)

Viventia Biotech Inc. today announced that it disclosed updated clinical data for its anti-cancer therapeutic, Proxinium(TM) (VB4-845), in two poster presentations on Saturday, May 14th given at the 2005 American Society of Clinical Oncology’s (ASCO) annual meeting in Orlando, Florida being held from May 13-17, 2005.

Dr. Nick Glover, President and CEO of Viventia Biotech, commented: “In these poster presentations, we provided an update on previously disclosed clinical data demonstrating that Proxinium(TM) has a good safety profile and beyond this, that the drug can produce very encouraging efficacy results including a demonstrable survival benefit in patients with refractory head & neck cancer.”

The first poster presented by the Company (Abstract No. 5569) entitled “A Phase I study of VB4-845 in patients with advanced, recurrent head & neck cancer on a weekly dosing scheme,” disclosed updated results from an exploratory Phase I efficacy trial using direct intratumoral injection of Proxinium(TM) as a monotherapy. A total of 20 patients were enrolled in the study and 18 were considered evaluable at the end of the trial. VB4-845 administered on a weekly basis for 4 weeks was safe and well tolerated. The maximum tolerated dose (MTD) on this schedule was determined to be 930 (micro) g/day. Preliminary results from this study were previously described in a press release dated March 29th, 2005.

Although this study was primarily designed to evaluate safety and tolerability, clinical observations indicated that VB4-845 demonstrated promising anti-tumor responses against Ep-CAM-positive SCCHN tumors in a highly treatment-refractory patient population. The final efficacy analysis showed that 25% of patients who expressed the therapeutic target for Proxinium(TM) had a complete response to therapy (complete disappearance of treated tumor); 63% had an objective response (significant or partial shrinkage of treated tumor); and 88% had tumor growth control (objective response or stabilization of disease).

The second poster (Abstract No. 5539), entitled “A Phase I Open-Label Study to Evaluate Safety, Tolerability and Pharmacokinetic (PK) Profile of VB4-845, an anti-Ep-CAM Immunotoxin, in Subjects with SCCHN,” described updated results from a 24 patient Phase I dose-escalation trial to determine the safety, tolerability, pharmacokinetic (PK) profile and preliminary efficacy of intratumorally injected VB4-845. VB4-845 administered on a monthly schedule of five consecutive days dosing followed by 23 days rest was found to be safe and tolerable at all dose levels tested, suggesting that higher dose levels could be explored. A maximum tolerated dose (MTD) was not reached. Preliminary results from this study were previously detailed in a press release dated September 27th, 2004.

Although this study was primarily designed to evaluate safety and tolerability, clinical endpoints indicate that VB4-845 treatment showed promising efficacy against Ep-CAM-positive SCCHN tumors in a highly treatment- refractory patient population. In this study, Proxinium(TM) therapy yielded an objective response rate of 43% and a tumor growth control rate of 71% from those patients that expressed the EpCAM antigen. An analysis of the survival data from this trial determined that the median survival rate for EpCAM positive patients who showed a response to Proxinium(TM) in this study was 301 days, compared to a median survival of 125 days for those patients that were EpCAM negative (the expected median survival is approximately 120-150 days).

About Proxinium(TM)

Proxinium(TM) combines a powerful cytotoxic protein payload with the highly precise tumour-targeting characteristics of a monoclonal antibody. A single molecule of the cytotoxic protein payload, Pseudomonas exotoxin, is capable of killing a cancer cell. The antibody fragment of Proxinium(TM) targets EpCAM – an antigen that is highly expressed on many epithelial cancers including head & neck cancer, ensuring that the payload is delivered directly to the tumour.

Proxinium(TM) received U.S. Orphan Drug designation from the FDA for the treatment head and neck cancer in March 2005. Head and neck cancer is the 9th most common cancer in North America, with approximately 50,000 new cases diagnosed annually in the U.S. alone, leading to 14,000 deaths annually. Head and neck cancer recurs in 60 – 70% of patients. The historical median survival time for patients with advanced, refractory head & neck cancer is less than six months.

About Viventia Biotech:

Viventia Biotech Inc.is a biopharmaceutical company developing Armed Antibodies(TM), powerful and precise anti-cancer drugs designed to overcome various forms of cancer. Viventia’s lead product is Proxinium(TM), which combines a cytotoxic protein payload significantly more powerful than traditional chemotherapies with the highly precise tumour-targeting characteristics of a monoclonal antibody. Proxinium(TM) is in clinical development for the treatment of head and neck cancer and bladder cancer, and is expected to enter advanced clinical trials in 2005.