JX-594 is an oncolytic virus (also known as Pexa-Vec, INN pexastimogene devacirepvec) developed by Jennerex and partners: Transgene S.A.; Lee's Pharmaceutical Holdings Ltd.; and Green Cross Corp. Pexa-Vec is designed to target and destroy cancer cells.
JX-594 is a modified Copenhagen strain (or Wyeth strain) vaccinia poxvirus engineered by addition of the GM-CSF gene and deletion of the thymidine kinase gene which limits viral replication to cells with high levels of thymidine kinase, typically seen in cancer cells with a mutated RAS or p53 gene. The virus also has the LacZ gene insertion under control of the p7.5 promoter. The virus kills the infected/cancer cells by lysis and also expresses GM-CSF which may help initiate an anti-tumour immune response. 
In clinical trials doses have been administered by intratumoral or intravenous injection.
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A global Phase 3 trial (the PHOCUS trial) http://www.pexavectrials.com for patients with advanced stage hepatocellular carcinoma will begin enrolling patients in late 2015. Two Phase I trials have reported results and a phase II trial for primary liver cancer, alone and in combination with sorafenib have been completed.
JX-594 Phase I results in 23 patients had encouraging results in 6 of 8 high dosed patients. A small (30 patient) phase II trial in advanced hepatocellular carcinoma (HCC) showed an increased median overall survival of 13.8 months compared 6.7 months for a lower dose (p=0.029).
- Jennerex Granted FDA Orphan Drug Designation for Pexa-Vec in Hepatocellular Carcinoma (HCC)
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