JX-594

JX-594 is a genetically-engineered, targeted, armed vaccinia virus designed to destroy both injected primary and non-injected metastatic tumors. This virus was engineered from the strain of vaccinia virus that is the basis for the vaccine that has been used in hundreds of millions of people in vaccination against smallpox. To further increase product safety, cancer-selectivity was enhanced through the deletion of a viral gene needed for significant replication in normal cells, but not in cancer cells. In addition, a gene encoding an immunostimulatory protein was inserted into the viral genome to stimulate patient immunity against the cancer. JX-594 therefore can destroy cancers through multiple mechanisms.

JX-594 was reportedly well-tolerated in a Phase I/II clinical trial of seven patients with metastatic melanoma (REF: "Mastrangelo & Lattime, Cancer Gene Therapy (1998) 6: 409-422").

Five of seven (71%) patients had tumor responses (including complete responses) at the site of JX-594 injection. Four patients in the trial had dermal metastases at the time of entry into the trial that were not injected directly; these dermal metastases reportedly regressed in all four patients. Non-dermal metastases did not reportedly respond. These results suggest that oncolytic virotherapy, and specifically JX-594, has the potential to treat distant metastatic disease.