04 February 2006

Making an Ally of a Virus to fight Cancer

Thanks to medicineworld.org cancer blog for pointing out a fascinating study in the use of the Newcastle Disease Virus for treating cancer.

The study is reported at Isracast.com.
Professors Amos Panet and Zichria Zakay-Rones, from the Department of Virology at the Hebrew University Hadassah Medical School, have been involved during the past five years in research that could create a new and effective weapon in the fight against cancer, as well as change the way we look at viruses. As an obligatory parasitic entity with no independent life of its own, a virus must enter a living cell in order to multiply. The viral life-cycle begins when the virus inserts its genetic material into the host's cell, forcing it to replicate the virus' components, and eventually leading to the death of the cell. The NDV-HUJ virus, discovered by the Hebrew University in Jerusalem team, acts in a similar way, except for its outstanding preference for infecting cancerous cells. NDV-HUJ is a natural variant of NDV (Newcastle Disease Virus) which usually affects birds. Being an attenuated variant (e.g., weakened virus), it is innately preferentially targets and replicates in certain types of tumor cells, leaving normal cells almost unaffected.

....Viro-therapy is not a new idea. Its roots could be found in the mid 20th Century, when a number of physicians noticed an interesting phenomenon: some of their patients, who suffered from cancer and had an incidental viral infection, or subjected to vaccination, were now improving, experiencing a remission from their symptoms. In the 40's and 50's, studies were conducted in animal models to evaluate the use of viruses in the treatment of tumors, and in 1956, one of the first human clinical trials with an oncolytic virus ("onco" meaning cancer, "lytic" meaning "killing") was conducted in patients with advanced-stage cervical cancer. Nevertheless, systematic research of this field was delayed for years, due to lack of more advanced technologies.

....Apoptosis or "programmed cell death" is the end stage in the life cycle of a cell. Every form of existing cancer treatment is aimed at causing selective apoptosis of cancer cells. The problem is that in cancer cells the apoptosis mechanism is damaged, thus allowing the cells to exist beyond their normal life span and multiply out of control. Existing cancer treatments use the apoptosis mechanism to destroy cancer cells, but due to the damage done to its apoptosis mechanism the cancer cell requires a stronger treatment in order to activate its "self destruct" mechanism. Stronger treatments mean more damage to normal cells in the body which is why Chemotherapy is considered such a harsh treatment.

....After receiving the NDV-HUJ virus treatment, one of the 14 patients exhibited a regression of the tumor, a surprising fact given the aggressive nature of the GBM cancer and the early phase of the clinical trials. These initial results are encouraging since no adverse side effects were noticed in the treated individuals.

The researchers will continue to study the mechanisms of viral infection of tumor cells, and ways in which this approach to therapy might strengthen the apoptosis mechanism in tumor cells. They will also work on maximizing the selectivity of the virus for the tumor cells. The virus used in the initial studies was an attenuated strain. Other forms of the virus might be more efficient, if the researchers can be sure the virus will not escape into the wild bird population.

There is much to learn about the nature of cancer, and the interaction of the human body's immune system with the malignancy. Introducing a viral infection into the total picture makes the study even more complex. It will take time to sort things out. The basic approach should be ultimately productive.

Update: Newhopeblog and Hyscience blog had previously posted on this story. I only discovered those blogs after posting this story, but the Newhopeblog in particular appears to have a lot of good medical resources. I plan to add them to my blogroll. Their source for the story was the ever capable Medical News Today.
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