Saturday, July 07, 2007

Update on Cancer Gene Therapy

The latest issue of Cancer Gene Therapy has a very informative review article on the state of cancer gene therapy. Here is a sample:

"Recent developments in the use of adenoviruses and immunotoxins in cancer gene therapy"
Z R Yang et. al.

Gene therapy, initially hailed as a revolutionary biomedical technology with enormous potential for curing almost any disease, has come a long way on a turbulent course in a relatively short period of two decades. Its original concept for treating disease by replacing a lost or defective gene has broadened to encompass a variety of approaches of introducing genetic materials into cells for therapeutic purposes. A large number, nearly 1000, gene therapy clinical trials have been or are being conducted worldwide, and two-thirds of these are for cancer.1 While the technology itself is still evolving, gene therapy is particularly suitable for cancer, since most patients with cancer who are eligible for clinical trials, are terminal with poor prognosis and dismal outcomes due to failing conventional treatment. Thus gene therapy, with its limited efficacy (in part due to the late stage of disease at which patients are treated in clinical trials) and sometimes severe side effects, often provides the best or the only alternative for patients who are refractory to conventional treatments. In addition, the lower cost of gene therapy when compared with conventional treatments makes it especially attractive particularly to patients with limited financial means and those in developing countries.

Cancer gene therapy has made remarkable progress over the past few years, reaching some significant milestones. The first cancer gene therapy clinical trial was performed in the early 1990s in the US; however, in China it was 10 years later – in the Spring of 2004 – that the first therapeutic gene, adenovirus (Ad)-p53, was approved for commercial use by China's State Food and Drug Administration (SFDA) for head and neck squamous cell carcinoma (HNSCC). Gendicine is a biologically active, replication incompetent, recombinant Ad-p53, and has been used in clinical trials for hepatocellular (HCC), nasopharyngeal (NPC), gastric, liver, lung, breast, prostate and ovarian cancers in addition to HNSCC. The infectivity of the virus is limited to one cycle and the Ad vector does not integrate into the host genome. Doses are 1–4 virus particle units (v.p.u.)/injection/week usually for 4 consecutive weeks. Side effects have been predominantly self-limited fever in 32% of patients and responses to date have been in patients often refractory to conventional treatments. Some of the best results with this treatment have been seen when Gendicine has been used in combination with conventional treatments such as with radiation to treat NPC3 or with transcatheter hepatic arterial chemoembolisation to treat HCC.


The image here is "breast cancer: cancer cell." Online Photograph. Encyclopædia Britannica Online. 7 July 2007]