Reporter 437, 24 May 1999
A pioneering cancer treatment has been approved for use in the UK following extensive development and clinical trials by Leeds-based scientists and clinicians. Photodynamic Therapy can effectively treat certain types of cancer using a laser and a light-sensitive drug. It will soon be available to patients across the country.
The Leeds Centre for Photobiology and Photodynamic Therapy (PDT) is the largest in Europe and among the global leaders in developing the potential of PDT. The centre has carried out one of the largest clinical trials to support the approval of PDT, as well as extensive laboratory studies. Over 500 patients with certain types of advanced lung and oesophageal cancer have already benefited from the technique in the centre's trials. Patients are given an injection of the drug, which then spreads throughout the body, but concentrates in cancerous tissue. Without light, the drug is harmless, but when light is applied it becomes activated and kills surrounding cells. Therefore by accurately directing laser light within the body, tumours can be targeted and destroyed. The centre's director Professor Stan Brown said the approval of the drug ‘Photofrin’ means the approach will be used more widely in cancer centres across the UK. Staff from the Leeds centre have led a training programme for clinicians who wish to use PDT in their own hospitals.
"The licensing of Photofrin for use with lung and oesophageal cancer represents an important milestone in the development of PDT and other approvals are expected in the next year or two," said Professor Brown. "PDT is now an accepted therapy, not just for cancer but for other diseases also. There will now be strong pressure to develop new drugs and light sources and find new clinical applications. With funding already guaranteed for at least another five years, the Leeds centre aims to remain at the forefront of these developments," he said. The centre has recently been awarded grants and contracts valued at around £2.75 million, largely from Yorkshire Cancer Research, but also from industry. Professor Brown added that PDT drugs can also be applied as a cream, which can be easily spread over an area of skin cancer. Applying the activating red light can then be done with a simple lamp, a procedure which could potentially be performed in GPs’ surgeries. A cure rate of 90% for a type of skin cancer called Bowen's disease has been achieved in trials. Professor Brown believes this aspect of PDT could be licensed for widespread use within two years.
Centre members Dr Kirste Mellish and Dr David Vernon with Professor Brown
The Photofrin drug is very similar to the active component of haemoglobin, a protein found in the blood. Because of its similarity to this natural chemical, it is easily handled by the body and does not come with unpleasant, toxic side-effects, the only problem being that patients must stay out of direct sunlight for about a month after the therapy. Unlike radiotherapy, there is no limit to the number of treatments which can be given. Sixteen patients have also been treated for pituitary tumours in the brain. "Though the study is still in its early stages the results have been very promising," said Professor Brown. The work is now being extended to treatment of meningioma (a form of benign tumour) in the brain.
The thirty-strong Leeds centre includes researchers from four University departments, who work closely with colleagues at hospitals throughout the region. The centre's staff and students work together on a day-to-day basis, but also retain a 'home' in their own disciplines, ensuring they remain aware of developments. In addition to cancer, PDT is also being applied to other diseases. The centre is using it to treat the gynaecological disorder menorrhagia. This is a very common problem, which often requires hysterectomy. Successful PDT treatment can remove the need for such surgery. The technique is also being used to prevent progression of the disease 'age-related macular degeneration', the major cause of blindness in the elderly population.
Clinical trials are already well advanced and appear to show remarkable benefit in a disease where there is little or no alternative treatment. "Although the Leeds centre is not directly involved in these trials, we are nevertheless delighted that the benefits of PDT are spreading more widely," said Professor Brown.
Professor Stan Brown leads a 30-strong team developing photodynamic therapy, a pioneering method of treating certain cancers.
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Further information on the use of PDT in macular degeneration can be obtained by calling the special helpline: 0171 814 5100.
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