A Magnetic Breakthrough: Revolutionising Brain Tumour Treatment

Using Magnetic Drug Targeting to Overcome the Blood-Brain Barrier

Gliomas are a type of brain tumour that originates in glial cells. The most common treatment option for gliomas is surgery, which is invasive and cannot always remove the entire tumour. Consequently, surgery is often followed by additional treatments.

Chemotherapy is a potential alternative to invasive surgery for brain tumours, but most chemotherapy drugs struggle to penetrate the blood-brain barrier. This protective barrier allows oxygen, nutrients, and other essential substances to pass through while blocking harmful substances like bacteria or viruses. It also prevents most chemotherapy drugs from reaching the brain. Only a few chemotherapy drugs can cross the blood-brain barrier, so invasive surgery remains the primary treatment for brain tumours.

To make chemotherapy a more viable option for treating brain tumours, researchers must find a way to help the drugs penetrate the blood-brain barrier. One promising approach involves the use of magnets.

The Early Days of Magnetic Drug Targeting

Although the concept of using magnets to deliver treatments to specific sites in the body may sound futuristic, the idea was first proposed in the 1960s and explored for cancer treatment in the late 1970s. The technique, known as magnetic drug targeting, involves attaching a drug to a magnetic nanoparticle (MNP) and using a magnet to guide the particles to a specific location in the body.

This method ensures that the drug delivery is focused, maximising the amount of drug that reaches the tumour while minimising off-target effects. Early-phase clinical trials of magnetic drug targeting have shown promising results, but they have been limited to cancers with tumours close to the body's surface, such as liver cancer.

Brain tumours pose a more significant challenge, as their deeper location within the body makes it difficult for magnetic fields to reach them. Stronger magnets, like those used in MRI scanners, are needed to create stronger magnetic fields.

However, MRI scanners are bulky, noisy, and uncomfortable, making them unsuitable for regular chemotherapy sessions lasting several hours. To address this issue, researchers at the University of Sheffield have designed a more suitable device for magnetic drug targeting.

A Magnetic Helmet for Brain Tumour Treatment

Researchers at 英国谢菲尔德大学 , partly funded by Cancer Research UK (CRUK) , have developed a small, portable device for mice with brain tumours. The device uses neodymium magnets, which are stronger than those used in previous trials but much smaller and more portable than MRI magnets.

The researchers built a helmet-like device containing these magnets and encased them to create a focused and stable magnetic field. After administering iron oxide MNPs intravenously to the mice and placing the helmets on them for 30 minutes, the researchers found that the MNPs had successfully entered the brain and concentrated in the tumour.

Next, the researchers attached the MNPs to temozolomide, a chemotherapy drug for brain tumours. They administered it to the mice intravenously three times over four days, placing the helmet on the mice each time. The results showed that the magnetised temozolomide significantly reduced the size of the mice's tumours and extended their survival.

Importantly, the mice treated with magnetised temozolomide survived longer than those treated with temozolomide alone, indicating that the magnet made the same dose of drug more effective against the tumour. Furthermore, no MNPs were found in any of the mice's liver, spleen, or lungs, suggesting that the body can safely break down and excrete the particles without damaging other organs.

Scaling Up and Future Possibilities

This study demonstrates the potential of magnetic drug targeting as a viable treatment option for brain tumours. The next steps for the researchers are to test other drugs that are currently not used for brain tumour treatment, potentially expanding the range of available treatment options.

Dr Faith Howard, a Cancer Research UK-funded postdoctoral research associate in the team, explains that the ultimate goal is to make these treatments less invasive. Directly injecting chemotherapies into the brain can be risky and is limited in the number of times it can be performed. A delivery system like magnetic drug targeting could enable multiple administrations over time, providing more drug options, better patient recovery, and shorter hospital stays.

Before this device can be used to improve human treatment, it must be tested on larger animals with similarly sized brains. To prepare for this, the researchers have already demonstrated that the magnetic device can be scaled up to human size. These larger magnets can penetrate approximately 10 centimetres into the brain, potentially targeting even deep-seated tumours.

In a trial with brain cancer patients, the research team fitted helmets containing the scaled-up magnets and asked for feedback on their comfort and functionality. While the device may not be ready for immediate use in humans, magnetic drug delivery can transform brain tumour treatment, sparing more patients from invasive surgery and offering more flexible treatment options.

In conclusion, the breakthrough research on magnetic drug targeting conducted by the University of Sheffield team has shown significant promise in revolutionising how brain tumours are treated. By using magnets to help chemotherapy drugs cross the blood-brain barrier, a new range of treatment options could become available to patients. With further research and development, magnetic drug targeting could change the face of brain tumour treatment, making it less invasive and more effective for patients.