Single-agent phototherapy system to fight cancer

Researchers believe the evolving field of phototherapy might become a new and promising addition to the ways cancer is being treated today

Researchers have developed a new approach that uses a single chemical compound to make cancer cells glow when exposed to near-infrared light, which can help a surgeon identify the cancer and remove it more effectively.

The compound, silicon naphthalocyanine, also creates heat and reactive oxygen species within any remaining cancer cells, killing these.

In tests completed with laboratory animals, tumours were completely eradicated without side effects, and did not return.

When perfected, researchers believe the evolving field of phototherapy could become a new and promising addition to the three primary ways most cancer is treated today — surgery, radiation and/or chemotherapy.

Phototherapy clearly has the potential to make some of those approaches more effective than they already are, researchers said.

Since this is a different form of therapy, however, it could have special value with cancers that have formed resistance to chemotherapeutic drugs or present other problems that cannot be managed with existing therapies, they said.

“We’ve now developed an improved formulation that’s biodegradable, simple, robust and reproducible,” said lead author Olena Taratula, a research assistant professor in the Oregon State University/Oregon Health and Science University College of Pharmacy.

“This system that can make cancer cells glow is like giving the surgeon an extra pair of eyes,” she said.

“And, the compound we’re working with now is inexpensive and appears effective at killing any cancer cells that remain.”

Research so far has studied ovarian cancers in laboratory animals but the researchers said conceptually the treatment might also be useful for other solid tumours. There were no apparent side effects on animals tested.

The system that helps deliver the silicon naphthalocyanine to cancer cells is an alternative to a dendrimer-based delivery system reported earlier this year, and uses a copolymer called PEG-PCL as the biodegradable carrier.

The carrier causes the silicon naphthalocyanine to accumulate selectively in cancer cells and reach a maximum level in these after about a day, at which point surgery and phototherapy treatment would be done. The compounds are then naturally and completely excreted from the body.

“A single-agent based system is simple and very good at targeting only cancer tumours and should significantly improve outcomes,” said Oleh Taratula, an assistant professor in the Oregon State University/Oregon Health and Science University College of Pharmacy.

The study was published in the journal Chemistry of Materials.