http://www.utsandiego.com/news/2013/feb/11/cancer-gets-deadly-tan/

By tweaking a virus known to attack cancer, San Diego scientists have developed a clever two-in-one technique for detecting tumors and making them more vulnerable at the same time. The method was tested in mice, and it could be headed for human clinical trials in as little as a year.

Researchers at the San Diego biotech company Genelux genetically engineered the cancer-killing virus to produce melanin, responsible for skin color and tanning. Tumors infected with the virus become darker than the surrounding tissue. They become visible through optical imaging, as well as MRI, or magnetic resonance imaging.

Moreover, the melanin-darkened tumors preferentially absorb near-infrared light and covert it to heat. A two-minute exposure killed nearly all of the tumors by heating them, according to a study published Monday in the Proceedings of the National Academy of Sciences.

Human clinical trials of this therapy could begin after regulatory approvals are granted, said Aladar A. Szalay, Genelux president and CEO, and the study's senior author. The first author is Jochen Stritzker, of Genelux and the University of Würzburg, in Germany.

The virus is from a well-studied variety called vaccinia, so its safety profile is known, Szalay said. A vaccinia virus was used in the first smallpox vaccine more than two centuries ago. And Genelux is using the virus in an ongoing clinical trial that has shown preliminary evidence of safety and efficacy.

[1] Hard-to-reach tumors in places such as the brain or pancreas are among the logical choices for the therapy, Szalay said.

Eventually, the melanin technology could become a tool in the new field of "theranostics," combining therapy with diagnosis, the study said.

Attempts have been made to use melanin for cancer diagnosis and treatment. But those failed because the tumor didn't make enough melanin to be effective, Szalay said. Genelux used a virus known for making huge amounts of viral protein in the cells it hijacks, causing plentiful melanin production.

Cancer-killing, or oncolytic, viruses selectively attack solid tumors because the tumors tend to be shielded from the body's immune system, which kills the viruses elsewhere. Biotech companies such as Genelux are working to enhance such viruses so they can be safely and effectively used in people.

[2] Besides vaccina, other oncolytic viruses used in clinical trials are adenovirus, reovirus, measles, herpes simplex and Newcastle disease viruses. Conclusive proof of efficacy remains to be demonstrated.

In the existing trial, privately held Genelux is testing a viral cancer therapy called GL-ONC-1. The trial uses a cancer-killing virus, genetically engineered to produce a fluorescent protein that shows where the cancer exists.

In November, Genelux said a Phase 1/2 trial showed that the "virotherapeutic" was well tolerated when applied into the peritoneal cavity. Analysis of the peritoneal fluid showed malignant cells were infected and killed by the therapy.

Genelux was founded in 2001 to develop diagnostics and treatments for cancer and inflammatory diseases.

Solid tumors are the most difficult to treat with conventional therapies, once they have metastasized. Another biotech working with oncolytic vaccinia viruses in solid tumors, San Francisco-based Jennerex, reported last week it had achieved positive results in a clinical trial of its therapy for advanced liver cancer.

Results of the study were published in the journal Nature Medicine.

[3] Jennerex is testing JX-594, a strain of vaccinia genetically modified to kill cancer cells, stimulate an immune response against the cancer, and to reduce blood supply to the tumors by destroying blood vessels.