Cancer treatments have evolved through the years. Researchers from Washington University sought another treatment that can eventually treat even the deepest of cancers. They developed a phototherapy method that can bring light directly to tumor cells, no matter how deep they are.
The researchers decided to use laboratory mice for their model of cancer and they applied light-based therapy to the deep tissues that were never before accessible to any other chemotherapy treatment. However, rather than shining an outside light, they directed the light to the tumor cells. Included were photosensitive source of free radicals that can be activated by the light to destroy cancer.
Light was used to treat cancer for some time now; however, phototherapy will only be effective where the light can reach limiting to its use for just skin cancer or areas where an endoscope can reach like the stomach and gastrointestinal tract.
In the study, that was published in the journal Nature Nanotechnology, the light source relied on the phenomenon called Cerenkov radiation, which also known as Vavilov-Cherenkov radiation, is responsible for the characteristic blue glow of underwater nuclear reactors and is used by doctors to diagnose cancer. It is also produced when charged particles travel and has been shown to induce death in a variety of cancer cell lines.
Senior author Samuel Achilefu, PhD, professor of radiology and of biomedical engineering at Washington University told Drug Development and Discovery, "Phototherapy works very well and has few side effects, but it can't be used for deeply embedded or metastatic tumors."
"In general, shining a light on photosensitive materials generates free radicals that are very toxic and induce cell death. But the technique has only worked well when light and oxygen can get there. The need for oxygen and the shallow penetration of light in tissue have limited advances in this area for decades," he added.
The researchers Dr. Achilefu and first author Dr. Nalinikanth Kotagiri, postdoctoral researcher, concentrated on a commonly used imaging strategy called FDG-PET. Pet scans have been used for years to diagnose cancer. Hence, with this technique, patients undergo the pet scan before receiving intravenous radiolabeled sugar molecules namely fluorodeoxyglucose (FDG).
Therefore, since tumors use sugar for growth, with the FDGs, the tumors can appear in the scan no matter where they are in the body. The researchers found out that fluorine would produce Cerenkov radiation to kick start a photosensitizing agent and will be delivered in the location of the tumor.
Dr. Achilefu explained, "FDG is one of the most widely used imaging agents in the world. That's the beauty of this treatment paradigm. It's used in hospitals today to find primary and metastatic cancer. So with FDG as our light source, we needed to find a material that becomes toxic when exposed to the light it produces."
When tested on mice, the injected FDG which are cancer-seeking nanoparticle, had the most significant effect because after 15 days, the tumors were eight times smaller than the control group of untreated mice.
Furthermore, the mice which received the treatment survived 30 days compared to the average 15 days for untreated mice. Hence, the treatment is effective in prolonging the life of mice, and future human trials can show promise as a new effective cancer treatment.
