8 July 2008
Introgen Therapeutics Inc. has become the first company to apply for FDA approval of a gene therapy drug to treat cancer (see press release). Although high profile gene therapy trials reported in the media have largely been for rare inherited diseases such as muscular dystrophy (see previous news), in fact two-thirds of all gene therapy treatments currently in clinical trials are for types of cancer (see Gene Therapy Clinical Trials Worldwide).
Advexin® has been developed to treat recurrent, refractory head and neck cancers and works by using a deactivated cold virus to deliver the p53 tumour suppressor gene into cancer cells. Abnormalities in the p53 gene are associated with many forms of cancer, and restoration of a functional gene can trigger tumour suppression mechanisms without harming healthy cells. The drug has been shown only to work on patients who have low levels of the functional p53 gene; consequently clinical trials incorporated common diagnostic tests to identify patients most likely to benefit from Advexin® treatment. This involved pre-treatment tissue analyses to determine p53 profile status; two-thirds of the patients with head and neck cancers were able to take the drug.
Introgen has requested Priority Review from the FDA, if granted the FDA will have six months from the submission date to take action. This review is generally granted to compounds that provide significant medical benefit compared with existing treatments. Introgen’s submission is based on positive phase II and III trials and if successfully granted Priority Review, could result in a decision by 2009. Introgen’s subsidiary in Europe, Gendux Molecular Limited has also applied for approval from the European Medicines Evaluation Agency (EMEA). Although the submissions are for use of Advexin® to treat head and neck cancers, it may have the potential to treat other types of cancers such as breast and lung cancer and clinical trials are currently underway to assess this.