Dr Pål Selbo explains a new mechanism scientists at the Norwegian Radium Hospital have developed developed to deliver anti-cancer drugs. Photochemical internalisation (PCI) is based on the light activation of photosensitisers. When light is absorbed by the photosensitiser it induces the oxidisation of endosomes and lysosomes membranes, causing them to release their contents. PCI uses red light as this penetrates furthest into the patient’s body (1cm) without causing any serious adverse effects. PCI utilises the high affinity photosensitisers have for tumour tissues in order to accurately deliver drugs to the site where they are needed and allows clinicians to kill cancer cells using three different mechanisms:

Shutting down the micro-vascular network of the tumour;
Killing cancer cells directly through apoptosis or necrosis;
Stimulation of the immune system.

Dr Selbo discusses the promising results of the phase I clinical trial which assessed the delivery of bleomycin using PCI in patients with head and neck cancer; talks about the planned phase II study and outlines the potential to use this technique in the treatment of sarcoma and the local control of many other tumour types.