Genetically engineered viruses capable of selectively targeting cancer cells while leaving healthy cells unharmed are gaining popularity as a promising oncolytic treatment. San Francisco-based biotech firm Jennerex debuted JX-594, a genetically engineered virus that can selectively target tumors and cancerous cells without affecting healthy tissue. JX-594, derived from a virus strain once used in the smallpox vaccine, attacks and lyses cancerous cells after viral replication, reducing blood supply to the tumor and increasing the body’s immune response. Administered intravenously, JX-594 has the potential to prevent metastasis. Back in May, Jennerex announced the success of its Phase I clinical trials and has partnered with French biopharmaceutical firm, Transgene, for Phases IIb and III. JX-594 is currently being tested on patients with liver cancer and metastatic colorectal cancer (mCRC). Transgene is set to receive European commercialization rights, and hopes to market the drug by 2015. Jennerex is working on additional viral strains targeting other cancers, including pancreatic and prostate cancers.
In related news, CZ BioMed, a Florida startup, recently introduced RVLYSIN, a line of oncolytic viruses targeting various cancers. RVLYSIN is a genetically engineered virus derived from the common cold virus. Early results demonstrate that RVLYSIN localizes to tumor cells and kills them primarily through lysis. Lysis triggers a subsequent systematic anti-tumor response, including attracting high local concentrations of interferon (IFN) to protect healthy cells by limiting viral replication. CZ BioMed also claims RVLYSIN can induce apoptosis in tumor cells. Currently in the pre-clinical stage, CZ BioMed demonstrated PANRVLYSIN (its product targeting pancreatic cancer) is well tolerated in mice. The company is seeking interested partners to initiate Phase I trials.
Although oncolytic viruses promise minimal side effects (similar to a cold) and potential to replace chemotherapy, concerns remain over dosage and efficacy. JX-594 and RVLYSIN share the same primary mechanism – lysis. And cancer cells are a preferred host due to their rapid growth and vulnerability to a second infection (for certain types of cancer). At this early stage, results have largely been inconclusive, as researchers continue investigating the relationship between therapeutic effect and level of viral replication. Another key concern is the possibility of the tumor returning if the immune system manages to fight off the virus. Other oncolytic viruses in development – including Amgen’s OncoVex and Oncolytics Biotech’s Reolysin, both currently in Phase III trials – require direct injection into the tumor and additional chemotherapy, respectively. Clients interested in oncolytic virotherapy should stay tuned as we reach out to Jennerex and CZ BioMed for full briefings.


