| Destruction of Tumors by HSV |
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Oncolytic virus is applied to the tumor |
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Tumor cells support virus replication |
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HSV start to destroy tumor cells |
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HSV remain dormant. |
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Cancer-killing viruses
MediGene is developing cancer-killing viruses, so-called oncolytic viruses, for the treatment of various forms of cancer. These viruses are specific herpes simplex viruses, or HSVs, generally known as the cause of cold sores. MediGene uses these viruses, however, in a modified and "disarmed" form in order to make them utilizable as a therapeutic agent in humans. This was achieved by switching off certain genes that normally enable the virus to multiply in healthy cells, which would destroy these cells. As a result of this genetic modification, the HSVs are able to reproduce in tumor cells solely, since only these offer an environment that compensates for the loss of the removed viral genes. Consequently, the virus is able to replicate in the tumor cells, selectively destroying them without harming healthy tissue.
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If this hypothesis is confirmed, oncolytic HSVs will act more selectively and efficiently than conventional cancer therapies do, yet without leading to severe adverse events. They could also provide a therapeutic alternative for the treatment of tumors that are inoperable or have developed a resistance to chemotherapy or radiotherapy. There may even be a synergistic effect in combining oncolytic HSV and standard therapies.
Preliminary clinical phase I trials with cancer patients have already yielded encouraging results: since 2004, MediGene has investigated the virus NV1020 in a continuative phase I/II trial in the indication liver metastases developing from colorectal carcinoma. In this trial, NV1020 is combined with standard chemotherapy. In 2005, a phase I trial of another HSV, i.e. G207 for the treatment of malignant brain tumors was initiated. This trial is conducted in cooperation between the University of Alabama, Birmingham, and MediGene, and is substantially supported by a SPORE grant (Specialized Program of Research Excellence) awarded by the National Cancer Institute.
Outlook
MediGene is planning to complete the clinical trial of NV1020 in 2007. Interim results should be published at the end of 2006. The clinical trial of G207 is continuing according to schedule.
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