Michael Weber

Weber Medical, Germany

Title: New Developments in Photodynamic and Sonodynamic Cancer Therapy

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Biography

Abstract

Photodynamic therapy (PDT) is one of the most promising therapeutic approaches in oncology. The procedures are not complicated and in contrast to traditional chemotherapy without severe side-effects if applied correctly. The principle is the photoactivation of a light sensitive substance (photosensitizer) which is injected into the bloodstream or directly into the tumor. 

After a certain amount of time cancer cells have fully absorbed the photosensitizer by endocytosis. The cancerous area is then irradiated by light of an appropriate wavelength, according to the absorption spectrum of the photosensitizer. The emitted photons are absorbed by the photosensitizer which is thereby shifted to a highly reactive state. It interacts with tissue oxygen, leading to the development of reactive singlet oxygen radicals which are cytotoxic for cancer cells.

Nowadays, 4 different photosensitizers are used for PDT: Chlorin E6 (stimulated by red laser light), Hypericin (stimulated by yellow laser light), Curcumin (stimulated by blue laser light) and Indocyaninegreen (stimulated by infrared laser light). All substances are available as intravenous injections.

To a smaller but still significant extent, these photosensitizers can also be activated by treating the cancerous tissue by low-dose shockwave therapy and therapeutic ultrasound therapy (summarized as sonodynamic therapy [SDT]). This applies a mechanical effect on the drug, causing the production of oxygen radicals, a physical destabilization of cell membranes and cavitation. Combining PDT with SDT thus improves treatment outcomes.

Furthermore, the therapeutic effect can be enhanced if PDT is combined with intravenous or hyperbaric oxygen therapy or by hyperthermia. 

Apart from that, the efficacy of certain chemo drugs can be improved by light stimulation, allowing physicians to administer them in lower dosages. PDT is thus often combined with low-dose chemotherapies.

For overcoming the hypoxic situation in tumor tissue a mixture of hyaluronic acid with H2O2 can injected intratumorally for improved oxygen supply. 

An additional injection of intratumoral DMSO can enhance photosensitizer uptake. 

In this lecture, the latest protocols and various case reports will be presented.