While photodynamic therapy (PDT) is a powerful light-induced cancer treatment, its application has largely been limited to surface cancers due to its inability to penetrate deeper than a centimeter of tissue. A new approach developed by NUS researchers will soon change that by wirelessly delivering doses of light into deeper regions of the body to activate light-sensitive drugs, potentially enabling the use of PDT in treating a wider range of cancers such as those of the brain and liver.
PDT is a more precise approach to cancer therapy that is also less toxic. In PDT, a light-sensitive drug, known as a photosensitiser, is triggered by a specific light wavelength to produce a form of oxygen that kills nearby cancer cells. PDT also shrinks or destroys tumours by damaging blood vessels in the tumour and starving cancer cells of essential nutrients. It could also activate the immune system to attack tumour cells.
Led by Professor Zhang Yong from NUS Biomedical Engineering and Assistant Professor John Ho from NUS Electrical and Computer Engineering, the NUS team created a tiny 15mm3 wireless device — the size of a peppercorn and weighing a mere 30mg — that can be easily implanted in the body, thus allowing PDT to go deeper and target the inner organs. The team was able to activate photosensitive molecules through thick tissues of more than 3cm, typically inaccessible by direct illumination.
The findings of the study were published in the scientific journal Proceedings of the National Academy of Sciences on 29 January.
Asst Prof Ho explained the novelty of their approach. “Powered wirelessly, the tiny implantable device delivers doses of light over long time scales in a programmable and repeatable manner. This could potentially enable the therapies to be tailored by the clinician during the course of treatment,” he said.
“Our approach of light delivery will provide significant advantages for treating cancers with PDT in previously inaccessible regions,” added Asst Prof Ho, who is also a Principal Investigator at the Biomedical Institute for Global Health Research and Technology at NUS.
The innovative technology also enables ongoing treatment to prevent reoccurrence of a cancer without additional surgery.
Prof Zhang said, “The application of the technology can also be extended to many other light-based therapies, such as photothermal therapy, that face the common problem of limited penetration depth. We hope to bring these capabilities from bench to bedside to provide new opportunities to shine light on human diseases.”
The team is looking into minimally invasive techniques for implanting their device, as well as integrating sensors to monitor treatment response in real-time. They are also working on developing nanosystems for targeted delivery of photosensitisers.
See press release.