I have written several articles on cancer in this blog before. Check out HERE, HERE and HERE. I must admit that it has become one of things that concern me a lot especially when I personally know more than a few people, including close relatives, that have succumbed to this silent killer. Therefore I find an article on Photodynamic therapy quite interesting and would like to share it with readers of my blog. Some of you might have heard about it, but those who haven’t, rest assure this is quite interesting.
Photodynamic therapy or PDT involves the use of drugs, known as ‘photosensitisers’, that only work when they have been “activated” by specific types of light. In cancer treatment, a photosensitiser is either administered topically (as a cream on skin for example) or injected into the bloodstream. After the drug has been given some time to be absorbed by cancer cells, light is then shined specifically onto the area that needs to be treated. Usually, the type of light used ranges from blue to deep red, as these have the required wavelength to penetrate through tissue. The light then causes the drug to react with oxygen and form a chemical that kills cancer cells.
Although there is currently no approved use of PDT for cancer treatment in Malaysia, local researchers have already started conducting clinical studies using this method of treatment. Among the latest researchers seeking to improve cancer treatment is that of Prof Dr L Y Chung from Universiti Malaya’s (UM) Department of Pharmacy. Together with his team, Prof Chung hopes to refine photodynamic therapy, a relatively new method of treatment that uses special drugs that are sensitive to light.
Prof Chung and his team’s findings were recently published in the Chemical Society Review journal as a paper titled “BODIPY Dyes in Photodynamic Therapy”. The research is a collaboration between UM, the Cancer Research Initiatives Foundation (Carif) Malaysia, and Texas A&M University, the United States The research team includes Dr Kiew Lik Voon of the Department of Pharmacology Faculty of Medicine; UM postgraduate pharmacology student Lim Siang Hui; Prof Lee Hong Boon of Carif’s Drug Discovery Laboratory; and Prof Kevin Burgess of Texas A&M University’s Department of Chemistry. While the research was funded by a high-impact research grant from the Higher Education Ministry, the exact amount of funding given is not known.
Photodynamic therapy, or PDT, has so far shown promising results for certain types of cancer, skin diseases as well as wet age-related macular degeneration (an eye condition that tends to cause loss of vision).
Prof Chung says that PDT potentially has several advantages over conventional cancer treatment such as surgery, radiation and chemotherapy.“(This includes) reduced long-term morbidity, less whole-body toxicity and less resistance issues so that such treatment can be repeated if needed,” he says. However, PDT has its own limitations, the most notable of which is that it is mainly applicable for the pre-cancerous and early stages of cancer. “Besides this, the highly localised nature of PDT… (means that it is) ineffective against metastatic cancer (where the cancer has spread widely),” says Prof Chung.
He adds that scientific advancements may overcome some of these limitations in the future. For example, with the use of fibre-optic devices, light can be better delivered to internal organs. There are also side-effects to the treatment; patients may develop photosensitivity for instance, where they would need to avoid exposing their skin to direct sunlight or bright indoor light. “Common skin photosensitivity reactions include development of mild to moderate rashes, swelling, itchiness, burning sensation and blisters,” adds Prof Chung.
While Carif has been conducting research on new photosensitisers since 2004, Prof Chung says the organisation then approached UM to partner in their research. He says a good photosensitiser should be water soluble so that it is able to circulate in the bloodstream. He adds that since most photosensitisers currently used are fatty compounds, they are less water soluble. Being fatty compounds also means that it is harder for the photosensitisers to target tumours perfectly, as they tend to stick to areas such as the cell membrane. Prof Chung adds that an ideal photosensitiser should be able to stay in the body long enough for it to accumulate in a tumour or cancerous area, and yet be able to naturally degrade fast enough so it does not turn toxic. In this regard, Prof Chung and his team decided to explore the viability of using a specific category of fluorescent dyes as photosensitisers.
“Bodipy (an abbreviation of oron-dipyrromethene) is a class of fluorescent dyes,” explains Prof Chung.
They have many characteristics of an ideal photosensitiser, including good light absorption ability, environment insensitivity (the ability to function in different environments), resistance to degradation, and little or no toxicity when not irradiated by light. From a chemistry standpoint, Bodipy is structurally simpler than the current photosensitisers that are clinically approved, so they are easier to make and modify.
Prof Chung adds that his team plans to develop a prototype drug based on their research within the next five years. While it may not radically change the face of cancer treatment just yet, the work of researchers like Prof Chung may hold some hope for the future.
Source: The Star Online
- Cancer Treatment In Malaysia: Photodynamic Therapy