Biotechnology is a hot area for investment at present and advances in cancer drugs continue, yet cancer remains one of the world’s biggest killers.
In many instances relating to treatment, the drugs are effective, but the targeting of them to a tumour is difficult. With regular healthy tissue, blood vessels hold a structure supplying oxygen and nutrients to cells which perform normally in how they divide and grow. Where cancerous tumours exist, this regular process turns to chaos, where growth is unregulated and vessels get starved of blood.
The problem this creates is when drugs are administered they don’t reach all of the areas that need to be reached, which allows the chances of a cancer returning to be that much greater. In addition to this, tumours contain quite allot of pressure which prevents drugs being absorbed via blood, which then get circulated around the rest of the body causing terrible side effects.
The Oxford Institute of Biomedical Engineering has been exploring ways by which these barriers to treatment can be taken away. The core challenge is two fold, one to contain the drug until it reaches its target area and the second, to ensure the tumour gets the optimum dosage.
There are also other challenges:
- How the drug can be released on demand after it has built up in the tumour
- Ensuring even release of the drug across the tumour
- Deliver an opportunity to be able to monitor progress of the treatment from outside the body.
The team at the Oxford Institute of Biomedical Engineering have created a way by which they can create tiny particles loaded with the drug, that can achieve very precise targeting. A number of ways to encourage the particles to release the drugs have been tested, including use of materials that react to a pH charge within the tumour and materials that deconstruct through heating.
Release of the drug
One of the most effective ways of ensuring the drugs are released from the particles is to target a beam of ultrasonic vibration at the particle. Ultrasound has obviously been used for some time to take images from the outside, of the inside of the body, and can also be tightly targeted for localised effect.
Particles that will react to ultrasound have to include gas and liquid which will vaporise. What happens to the liquid or gas is, when it is exposed to ultrasound it rapidly expands and then pushes the drug out of the particle.
Performing this routine results in a pulsating gas or vapour bubble that also delivers other useful routes to delivering drugs. The bubbles produced and resulting pressure by the ultrasound helps to drive the drug out of the blood and further into the tumour. The tests have shown that the drugs can be pushed in by up to 4x the depth and achieve a uniform spread within the tumour.
Research is also being undertaken using ultrasound and microbubbles which encourage tumours to be more permeable to drugs. This means that drug treatment can be sped up, leading to faster cancer cell death. There is a further benefit from the process whereby the motion of the microbubbles delivers another ultrasound signal that can be detected outside the body, enabling external monitoring of the status in real time.
The aim is to develop these processes in order to put them into clinical service within 5 years and help make cancer drugs more effective.