Introgen Therapeutics reported combined safety and efficacy results based on three multi-center, multi-national Phase 2 clinical trials of Advexin p53 gene therapy in 217 patients with recurrent, squamous cell carcinoma of the head and neck. These data were presented in a late breaking session at the 95th annual meeting of the American Association of Cancer Research taking place March 27-31, 2004 in Orlando, Florida.

The objective overall response rate of Advexin monotherapy was 10 per cent (complete and partial response with greater than 50 per cent reduction in tumour size). Tumour growth control (stable disease or better) was achieved in 59 percent of all treated lesions. The primary objective of the trials was to assess tumour growth control and safety following Advexin monotherapy in patients with recurrent head and neck cancer. All patients had failed previous conventional treatment.

"The primary endpoint results from the three Phase 2 trials confirm our previously reported findings regarding the activity and safety of Advexin," stated Robert E. Sobol, M.D., Introgen's senior vice president of medical and scientific affairs. "This multi-center, multi-national analysis is the first detailed report of the combined data from all of our Phase 2 trials in recurrent head and neck cancer. These results were collected from over 40 clinical sites in the U.S. and Europe. We are encouraged by the response and safety data and the consistency of the findings."

Secondary endpoints of the studies included assessments of patient survival. A difference was observed between patients treated with high doses and low doses of Advexin. Patients treated with higher doses had a statistically significant increase in median survival compared to patients treated with lower doses (243 vs. 119 days). Additionally, the overall median survival was longer in patients who were treated with Advexin followed by chemotherapy in each of the studies: Trial 202 (n=20) 330 days; Trial 201 (n=47) 260 days; Trial 207 (n=29) 246 days.

Advexin therapy was administered by intra-tumoural injections. Advexin treatment-related side effects were generally mild to moderate in nature and included transient injection site pain and fever. All patients had been previously treated with radiation therapy and 59 per cent had previous chemotherapy. To date, clinical investigators in North America, Europe and Japan have treated over 500 patients with several thousand doses of Advexin therapy, establishing a large safety database.

"We will continue to monitor the survival data from these Phase 2 uncontrolled, non-randomized studies and will further analyze survival duration as part of our ongoing controlled and randomized Phase 3 clinical trials in recurrent head and neck cancer patients," added Dr. Sobol.

There are two multi-national, multi-site Phase 3 trials of Advexin therapy, currently underway in recurrent squamous cell cancer of the head and neck. Introgen has received FDA Fast Track designation for Advexin therapy and Advexin has been designated as an Orphan Drug for the treatment of head and neck cancer under the Orphan Drug Act.

Advexin has been evaluated in a variety of cancer types and in combination with several standard cancer therapies, including radiation and chemotherapy. Data from several published preclinical and clinical studies have demonstrated the ability of Advexin to safely enhance the anti-cancer effects of radiation and chemotherapy treatment.

Advexin supplies p53 protein in very high concentrations in cancer tissue and selectively kills cancer cells. p53 is a normal constituent of cells and is known as a tumour suppressor because it inhibits the growth of tumour cells. One of the major roles of this protein is to eliminate cancerous cells by recognizing when the cell has been damaged by mutations and stopping cell growth to initiate repair. If the cell is damaged beyond repair, p53 initiates the cell death pathway to prevent the cell from growing out of control.