A Study of Recombinant Vaccinia Virus to Treat Unresectable Primary Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is estimated to be the third most common cause of cancer-related deaths world-wide, and the fifth most common cancer diagnosis. According to the National Cancer Institute (NCI), approximately 17,000 new cases of HCC are diagnosed annually in the U.S. In Canada, the predicted incidence for 2007 is 1,350 new cases. In addition, approximately 10,000 new cases are diagnosed per year in S. Korea, 35,000 in the E.U. and 45,000 in Japan. The five-year survival rate is estimated to be \<10% for all HCC patients. Given the poor prognosis of these patients there is a desperate need for new therapies. Surgical resection and liver transplant are the only curative treatment for HCC. Small HCC tumor(s) (less than 3 cm in diameter) can be resected by hepatectomy, the most effective treatment. Surgery was associated with a reported 50-60% five-year survival rate, but unfortunately was possible in only 10-15% of cases. Liver transplant is considered for patients with tumors that are unresectable but that are still limited exclusively to the liver, have no extracapsular or vascular invasion within the liver, and for whom there are no medical contraindications to transplantation. Patients with unresectable HCC that cannot receive liver transplantation, and who do not require systemic therapy, may be administered percutaneous ethanol injection therapy (PEIT), radiofrequency ablation (RFA), transarterial chemoembolization (TACE), and/or radioembolization, depending on the size of the intrahepatic tumors and the underlying liver function. HCC may be a good target for IT injection with JX-594 because of the relatively high rate of accessible tumors for injection, the positive response seen in a patient with HCC in a recently completed Phase I study of JX-594 intratumoral injection within the liver, excellent tumor responses in multiple preclinical cancer models, and the lack of effective, tolerable therapy for most patients with HCC who cannot receive curative surgery or immediate liver transplantation. Furthermore, it is speculated that JX-594 replication targets the EGFR pathway, and that it's spread within and between tumors is dependent upon the intratumoral vasculature; HCC has highly activated angiogenesis and EGFR pathways in the majority of cases.