A U.S. study published in the journal Nature recently showed that a single intravenous injection of a genetically engineered virus killed tumor cells in patients without harming normal cells. The small early trial showed that the experimental virus, JX-954 treatment, could persistently infect tumors with only minor and transient adverse effects. The trial included 23 patients with a variety of advanced tumors and was designed to evaluate the safety of JX- 954. Of the eight patients treated at the highest dose, six had stable or regressed tumors and seven had viral replication in their tumors but not in normal tissue. JX- 954 was prepared from the strain of virus most commonly used for smallpox inoculation, and the investigators confirmed that it is very safe and that the gene that causes viral mutation is missing in JX- 954. The virus is administered intravenously and can be administered systemically, which may have the effect of limiting the metastatic spread of tumor cells. The investigators note that the adverse effects of the virus treatment are mild compared to the significant adverse effects of chemotherapy, with flu-like symptoms lasting only 24 hours being common. The investigators will soon explore the effects of treating 120 patients with liver cancer in a phase IIB trial, as early trials have shown JX-954 to be highly effective against liver cancer. Other studies exploring viruses against tumors are also underway, but those viruses either need to be injected directly into the tumor or accompanied by chemotherapy. All of these attempts are challenging current conventional treatments, the investigators noted.