Tokyo ? Tokyo University Hospital will begin a clinical test in late August of a viral therapy in which viruses are injected directly into brain tumor patients, according to hospital officials.

It will be the first clinical trial in Japan to use viruses whose genetic makeup has been altered to destroy cancer cells in localized areas.

A team including professor Tomoki Todo of the university’s neurosurgery department is focusing on the herpes virus, which is believed to infect cancer cells easily.

As the herpes virus could damage even healthy cells, the team has altered three genes in the virus so it will reproduce only in cancer cells.

The clinical trial will be conducted on patients who have had a relapse of glioblastoma, the most malignant of brain tumors.

The virus will be administered to the cancer cells twice over a two-week period, and the team will monitor such elements as tumor size and whether nerve paralysis occurs.

The hospital is recruiting patients for the trial and is expected to conduct it on a maximum of 21 people, according to the hospital officials.

During an earlier experiment in which glioblastoma were implanted under the skin of mice, the tumors became smaller when the mice were injected with viruses.

However, if no further treatment were given, the tumors swelled to about 30 times their original size within 25 days. There were no abnormalities detected when viruses were injected into healthy mice.