China has become the first country in the world to grant a commercial license to a gene therapy medication.
The country's State Drug Administration granted approval to the treatment for head and neck squamous cell carcinoma last month and its developer, Shenzhen SiBiono Gene Technologies, plans to launch it in January into a market estimated to be worth $100 million in 2004.
The therapy, called Gendicine, was approved after five years of trials involving patients with late-stage HNSCC, mostly nasopharyngeal cancers. After eight weeks of therapy involving one intratumoral injection of the drug per week, 64 per cent of patients' experienced complete regression of the treated tumour and 32 per cent showed a partial regression.
Moreover, when combined with standard chemo- and radiotherapy, Gendicine improved treatment efficacy more than 3-fold compared to standard treatment alone. Patients were followed up for a median of three years with no relapses recorded.
The drug is based on an adenoviral vector, used to deliver the gene coding for p53, a tumour-suppressor protein that exists in mutated form in a number of common cancer types. SiBiono said that this vector differentiates it from gene therapies using retroviral vector delivery systems which led to complications and a suspension in clinical testing of gene therapies in the US. The company claims that the only side effect being grade I or II self-limited fever.
HNSCC predominantly strikes men after age 50, and until now prognosis for survival had been poor, despite combined surgery and chemotherapy or radiation therapy. There are about 300,000 new patients in China who are diagnosed with this malignancy each year. SiBiono is also planning to conduct additional testing to expand the utility of Gendicine into other forms of malignancy.
China has a stated ambition of developing a strong industry in genetic therapy, having launched a five-year programme to promote activity in this area in 2001.
Meanwhile, outside China, US company Introgen Therapeutics and partner Aventis is developing its own adenoviral p53 gene therapy under the Advexin trade name. This drug is in Phase II clinical testing in HNSCC, non-small cell lung cancer and locally-advanced breast cancer.
Other companies looking at p53-based gene therapies include Matrix Pharmaceuticals and Phogen/Canji.