Evidence of a dose dependent therapeutic effect from the JX-594 virus that infects and kills tumor cells in patients with advanced liver cancer is reported in a study published online this week in Nature Medicine.

JX-594 is a modified vaccinia virus. While Phase 1 studies had been performed using the virus, David Kirn and colleagues report the first dose-finding study of JX-594 and evidence that it can induce antitumor immune responses. The authors found that for patients with hepatocellular carcinoma (HCC) that received the high dose of virus, median survival was 14.1 months, compared with 6.7 months for patients receiving the low dose arm.

These results must be confirmed in larger placebo controlled trials and further studies will be necessary to fully ascertain the mechanisms of protective efficacy of JX-594, though these results do offer hope for a new approach to tumor treatment.