The targeted agent Advexin (p53 tumor suppressor therapy) improves survival compared with methotrexate among head and neck cancer patients with the p53 biomarkers. These results were recently presented at the American Association for Cancer Research (AACR) Centennial Conference on Translational Cancer Medicine 2008: Cancer Clinical Trials and Personalized Medicine.
Head and neck cancers originate in the oral cavity (lip, mouth, tongue), salivary glands, paranasal sinuses, nasal cavity, pharynx (upper back part of the throat), larynx (voice box), and lymph nodes in the upper part of the neck. Worldwide, head and neck cancer is diagnosed in approximately 640,000 people annually and is responsible for approximately 350,000 deaths each year.
Patients whose head and neck cancer has returned following prior therapy have suboptimal long-term outcomes with standard therapies and research continues to evaluate novel therapeutic approaches to improve these outcomes.
The field of genetics is emerging as a potential therapeutic tool in the treatment of cancer. Although still in clinical trials, researchers are testing and exploring the use of genetic strategies for several types of cancer.
Gene therapy, a type of treatment in the field of genetics, often involves the insertion of a functional, normal gene into a cell that has a dysfunctional gene that may cause or contribute to the growth of cancer.
One gene, called the p53 gene, is of major focus in the evaluation of gene therapy since a significant portion of cancers have been shown to have a mutation (alteration) of this gene.
The p53 gene, sometimes called the “cell suicide” gene, helps to keep normal cell replication under strict control. If there is a mutation in a cell’s DNA, or if a cell is infected with a virus, one action of the p53 gene is to stop further replication of this damaged cell and inhibit further progression of the mutation. This occurs by stopping the growth of the cell or causing the cell to kill itself (apoptosis). In cells that have a mutation within their p53 gene, there is no restraint on replication; this leads to uncontrolled, rapid growth of the cell-the characteristic trait of cancer.
Advexin® is a vaccine that has completed the last phase of clinical trials. It is comprised of a functional p53 gene that is inserted into a virus that causes the common cold (adenovirus). Advexin can be injected directly into the cancer, with the cancerous cells taking up the adenovirus as well as the functional p53 gene. Researchers speculate that Advexin may have a direct cancer killing effect as well as enhance anticancer effects of treatment since cancer therapy often damages the DNA of cancer cells. A normal p53 should recognize this damage and halt replication or induce apoptosis of the cancer cell.
Researchers recently conducted a clinical trial to compare Advexin to the chemotherapy agent methotrexate among patients with head and neck cancer that has returned or stopped responding to prior therapies. Results were analyzed according to the p53 biomarker that has demonstrated an associated treatment benefit with Advexin.
• Patients with the p53 biomarker associated with benefit from Advexin experienced significantly improved 6-month and one-year survival compared with those treated with methotrexate
• Patients that did not have the p53 biomarker experienced a significant survival improvement with methotrexate compared to Advexin.
• Advexin was associated with fewer side effects than methotrexate.
The researchers stated that treatment with Advexin among patients with the identified p53 biomarker improves survival over methotrexate among patients with head and neck cancer that has progressed following prior therapies. Advexin is not yet approved by the United States Food and Drug Administration (FDA).
Reference: Introgen Therapeutics. ADVEXIN(R) Shows Statistically Significant Six-Month and Overall Survival Benefit as Compared to Methotrexate in Prospectively Defined Biomarker Patient Population. Available at: http://phx.corporate-ir.net/phoenix.zhtml?c=190273&p=irol-newsArticle&ID=1178041&highlight=. Accessed July 2008.