An innovative technique involves making cancer cells absorb a molecule capable of destroying them when exposed to light. It also helps guide the surgeon in his actions during an operation.
This article is taken from the monthly Sciences et Avenir – La Recherche n°907, September 2022.
PTD, three little-known letters, but with strong therapeutic hopes against cancer. PTD (dynamic phototherapy, in English PDT) is already used today “routinely” to replace surgery against certain precancerous skin lesions, but also in the context of research to overcome other types of tumors: brain, lung , ovary, liver, pancreas. The test with several works mentioned by the hundred French specialists gathered during the third national day of the PTD, organized in Toulouse in the fall of 2021 under the auspices of the French-speaking Society of Medical Photonics.
“The PTD principle is based on a chemical interaction between three elements: a photosensitizing product, oxygen and light. “, summarizes Serge Mordon, former director of the Inserm Onco-ThAI unit (image-assisted laser therapy for oncology) based in Lille. He is one of the best specialists in France of this approach born on the other side of the Atlantic at the end from 1970 with the work of American oncologist Thomas Dougherty.The mechanisms of action of DPT, which are still being explored, appear to be related to immunity.
This technique, initially tested in esophageal and prostate cancer and age-related macular degeneration, is now the subject of nearly 500 clinical trials worldwide. In practice, it consists of making the cancer cells absorb a photosensitizer, a non-toxic molecule administered locally (applied directly as a cream to the skin) or orally or intravenously.
Molecules specifically targeting the tumor.
“The particularity of the different photosensitizers is that they are only activated at the moment of illumination with a laser that emits light whose wavelength is preferentially absorbed by the molecule used.[…]