New cancer therapy with viruses against tumors?

New cancer therapy: with viruses against tumors

14/02/2011

Viruses could make a significant contribution to cancer treatment in the future. Researchers at the German Cancer Research Center (DKFZ) in Heidelberg are working on a method to use viruses to fight tumor cells.

The scientists of the DKFZ hope to use viruses to develop a new approach to cancer therapy. „The basic idea of ​​virotherapy is this: Viruses are made to do what they are professionals, namely to destroy human cells,“ explained the Heidelberg molecular biologist Dirk Nettelbeck to the news agency „dpa“. If it succeeds in altering the viruses so that they destroy cancer cells, but the healthy cells do not attack, the new method could revolutionize cancer therapy.

Viruses help in the fight against cancer
The DKFZ has been working on the development of so-called oncolytic viruses for the treatment of cancer for a long time. As early as 2004, experts from the DKFZ reported that oncolytic herpes simplex viruses were used to achieve promising results in the elimination of chemotherapy-resistant tumors in preclinical studies. According to the DKFZ researchers, the treatment approach of virotherapy is based on observations made by physicians, who found a regression of the tumors in cancer patients who suffered from a viral disease at the same time. The destruction of the tumor cells „was observed only in isolated cases“, clarified, however, that „In principle, viruses can have a very good activity against tumors,“ stressed the molecular biologist Nettelbeck. „We molecular biologists now have to change these viruses so that they only destroy cancer cells, but leave the healthy cells alone“, Nettelbeck described the current joint research approach of the Dermatological Clinic Heidelberg and the German Cancer Research Center.

Virotherapy as a new treatment for cancer
The cancer cells should be directly attacked and destroyed with the help of virotherapy, whereby the viruses can either be injected directly into the tumor or into the bloodstream, explained Nettelbeck the beginnings of the new treatment method. In the body of the cancer patients or in the tumors, the viruses are supposed to multiply after the injection and kill only the cancer cells. The scientists of the DKFZ face several challenges in their research work. On the one hand, the viruses would have to be reshaped so that they do not attack healthy cells, on the other hand, a defense reaction of the organism should be avoided. The scientists are investigating several alternatives such as the temporary blocking of the immune system or a reorganization of the virus, so that they are not recognized by the immune system. „If you change the virus envelope, the viruses get a new structure“ and with the new one „dress“ the natural defense reaction of the organism could be avoided. „That is a complex matter though“, stressed the molecular biologist Nettelbeck.

Killing the cancer cells immediately after the injection?
With the new approaches of virotherapy, even small amounts of virus per cancer cell could be enough to destroy them efficiently, according to the DKFZ experts. A killing of the cancer cells is expected just a few hours after the injection. If there are problems in the course of virotherapy, with the help of the available drugs, at any time a termination of the virus replication is possible, so the assessment at the DKFZ. If a virus vaccine has been successfully developed, the researchers hope that, in addition to the direct effect of the virus against the cancer cells, a kind of inoculation of the body, which could cause the body's immune system to fight the cancer. Overall, cancer treatment with viruses would provide a good therapeutic alternative for tumors that can not be surgically removed or have developed resistance to chemotherapy or radiotherapy, the DKFZ experts assessed their research approach. In addition, synergies through combined therapy with viruses and standard treatments such as chemotherapy are conceivable. Whether virotherapy can be sufficient as the sole treatment method to successfully fight cancer can, according to the experts so far hardly judge. (Fp)

Image: Viktor Mildenberger