Overview of PDT


PhotoDynamic Therapy (PDT) is a long-established clinically approved, minimally invasive therapeutic treatment that optimises the use of non-toxic photosensitisers and visible light to produce cytotoxic reactive oxygen that kills malignant cells, shuts down tumours and stimulates the immune system.

Each photosensitising agent or drug is activated by light of a specific wavelength, which in turn determines how far the light can travel into the body to address specific cancer types.

Photosensitising agents are administered topically or intravenously. The photosensitiser concentrates at the site of the tumour and then light of a specific wavelength is shone on the cancer area, which activates the reaction in the tumour. When exposed to specific wavelengths of light, photosensitising agents produce a form of oxygen that destroys cancer cells without damaging nearby tissue.

The ability of a photosensitiser to kill cells depends upon the concentration of the compound and how much light energy is delivered to activate it.


In contrast to surgery, or radiotherapy and chemotherapy which are mostly immunosuppressive, PDT causes acute inflammation, expression of heat-shock proteins, and invasion and infiltration of a tumour by leukocytes.



Next-Generation PDT

Improved next-generation PDT based on the PhotosoftTM technology

Invion is developing an improved next-generation PDT based on PhotosoftTM technology - a chlorophyll-based (derived from plants) photosensitiser called chlorin e4 sodium.

PhotosoftTM technology is hypothesised to selectively accumulate within solid cancerous tumour tissues.

The PhotosoftTM technology is activated at multiple light sensitivity ranges across a broad spectrum, enabling it to be potentially targeted at both surface and deep-seated tumours. The PhotosoftTM technology can be used as a diagnostic tool to "light up" tumours, or, at a much higher wavelength, to activate oxygen free radicals that kill cells.

Invion's photosensitiser remains inert in a cancer cell if there is no light to activate it, and the photosensitiser rapidly clears from cells.