'Sniper' technique exterminates cancer cells

Military technology has been used to develop a new cellular "sniping" tool at the University. But this is a weapon which will do far more good than harm. Research led by Dr Paul Campbell, of the Division of Electronic Engineering and Physics, and Professor Sir Alfred Cuschieri (Surgery and Molecular Oncology) has demonstrated that cancer cells can be targeted and destroyed by a single blast of ultrasound.

This has led to a groundbreaking technique that will hopefully end the need for traumatic surgery and extensive drug therapy for cancer patients. It is hoped that the treatment, which has worked on several different cancer lines cultured in-house, could be available to cancer patients within 5 years.

Previous research had shown that microscopic gas bubbles injected intravenously will naturally cluster around a tumour site. What the team from Dundee has demonstrated for the first time is that, when those bubbles are stimulated by a microsecond range burst of high intensity ultrasound energy, the bubbles respond in such a violent fashion that they can puncture the cancer cells and kill them.

In a report published in the November edition of the journal Nature-Physics, they were able to establish this process beyond doubt using an ultra-fast imaging system, photographing at a rate of a million frames per second, and previously developed by the army specifically to observe the impact of ballistic shells and bullets with armour plates.

Advanced optics involving lasers and holography to hold the gas bubbles close to the tissue plane using only the force of light itself were developed by Paul Prentice, a PhD student with Dr Campbell's group, in collaboration with Professor Kishan Dholakia at the University of St Andrews.

Commenting on the research, Dr Paul Campbell said, "Conventional cancer treatment often requires surgery to cut out the diseased tissues, which by itself introduces significant trauma, pain and discomfort to the patient, often delaying recovery for extended periods. Because this kind of ultrasound treatment holds the promise of effectively focusing energy directly to a deep seated tumour site without the need for an incision, it is hoped that the level of collateral damage to the patient can be kept to the absolute minimum".

Under favourable circumstances, it is hoped that the ultrasound treatment could eventually make systemic chemotherapy treatments unnecessary. The gas bubbles injected into the patient can be coated with anti-cancer drugs that then enter the punctured cancer cells only at the tiny focused region of the ultrasound field. The drugs are therefore targeted to flood only the cancer cells in a one shot process, rather than repeatedly flooding the patient's entire body with the chemotherapy drugs. Such coated bubbles have already been developed in the United States. This should dramatically reduce the patient's recovery time and the associated pain and suffering of surgery and chemotherapy.

"It would effectively be a sniper treatment for cancer" said Dr Campbell. "The ultrasound activated bubbles target with single cell precision, so that the technique overall is a little like sniping at specific cancer cells, whilst ensuring that healthy tissues remain untouched."

"Our research has proved that the injected gas bubbles react to the ultrasound by instantaneously inflating just like a party balloon. Then they do something quite incredible. The shell of the inflated bubble deforms to develop a fast moving spike directed back into the nearby cancerous cell. When the spike hits the cell membrane it punches through it like a bullet, creating a tiny 'entrance wound' and allowing passage of molecules, which have included drugs, directly into those cells."

The research, which represents the culmination of a three-year project funded by an award of £630,000 from the UK Engineering and Physical Sciences Research Council (EPSRC), has also involved direct collaboration with a world-leading molecular delivery group at the Georgia Institute of Technology in Atlanta, USA.

"What we have achieved here is an important step forward in our understanding of the processes at large. In order to fully capitalise on this new knowledge however, it is critical that we achieve further funding to push the boundaries of this technology into fullscale clinical trials on humans.

"The possible benefits to patients are clear: no incisions, no scars, less trauma and a much reduced chance of infection from anti-biotic resistant species. This approach could represent a tremendous future adjunct to conventional surgery, and we certainly have the drive and indeed expertise to see this through given the opportunity."

Dr Campbell believes this is a win win situation for everyone concerned: "Not only could this benefit the patient but the NHS as a whole by reducing the cost in the long term of treating cancer patients. It is hoped that hospitals would be able to perform the treatment by undertaking minor modifications to their existing ultrasound equipment and we are already moving on discussions with the instrument manufacturers to accelerate this process at source."