Infrared light used to improve photodynamic therapy in model tumours

Researchers have developed a compound that can be activated with infrared light to kill cancer cells in model tumours, advancing the possibilities of photodynamic therapy.

Red laser light

Scientists have discovered a new light-sensitive compound which they suggest could improve photodynamic therapy (PDT) for cancer. 

The study was conducted at the University of Sheffield, UK. The team report that their sensitiser molecule uses penetrating infrared light to damage cells directly and potentially improve the success rate of PDT. 

When administered to the patients and activated by light, PDT molecules produce highly reactive oxygen-based species which kill cancer cells. However, current treatments have two main drawbacks:

  • sensitisers are only activated by light energies that do not penetrate tissues like skin very deeply
  • many tumours have low amounts of oxygen, so photoactivated sensitisers cannot generate the toxic compounds which kill cancer cells.

However, the novel compound solves both of these problems in one go. Not only is it activated by infrared or red light which can penetrate deep into the tumour, but it also directly damages DNA within cells without having to rely on oxygen.

The researchers have tested the compound on skin cancer models and observed that it kills cancer cells deep into these tumours. According to the team, the next step in their studies will investigate skin models, testing whether the compound can kill the tumour but leave healthy skin undamaged.

Lead researcher Professor Jim Thomas, from the University of Sheffield’s Department of Chemistry, said: “PDT is potentially a very attractive way to treat diseases such as skin cancer as it only works when the laser light is applied, so the effect can be focused into a specific place on or in the body. The sensitiser we have developed can potentially solve the two main problems that prevent PDT from being a commonly used anticancer treatment.”

The research was published in the Journal of the American Chemical Society.