Magnets made by soil bacteria offer hope for breast and prostate cancer

Scientists are developing guided projectiles that can be injected into patients' blood to attack their tumours.

The project builds on progress in two key medical fields. The first involves Viruses that attack tumours. The second focuses on soilbacteria that manufacture magnets which they use to align themselves in the Earth's magnetic field.

One of the project's leaders said that the approach was straightforward: we were using bugs as drugs. It has a lot of promise and is a twin approach.

Oncolytic viruses are the anti-cancer viruses that are being exploited by theSheffield group, who have been funded by Cancer Research UK. They can be modified to improve their efficacy and limit the chances of them infecting healthy cells.

A cancer cell will die after being exposed to an oncolytic virus. The US Food and Drug Administration has approved the use of T-Vec, a modified herpes simplex virus, to treat people with certain types of melanoma, a skin cancer.

The team that won the Roger Griffin prize for cancer drug discovery wants to expand the range of tumours that can be tackled this way. They want to focus on breast and prostrate cancers.

The problem is that oncolytic viruses attract the attention of the body's immune defences and only skin-deep tumours can be tackled this way.

Scientists say that a solution is to coat the viruses with magnetic particles. Magnets placed over a patient's body could be used to direct the projectiles to the tumours.

It is like having a coat of armour or a shield. A magnet is placed over a tumours and it will draw the virus quickly and directly to it.

An oncolytic virus had a diameter of about 180 nanometres, while the magnets needed to be about 50. The tiny magnets could be made in the laboratory, but we have found thatbacteria do a better job of manufacturing them than we could.

Some soilbacteria synthesise iron oxide nanoparticles. Microbial magnets are used as compasses that allow the microbes to navigate in Earth's magnetic field and help them find optimum conditions for their growth and survival.

Clinical trials on humans can begin soon if sufficient supplies are made. We need to take the next steps to bring this technique to a state where it can be administered to humans in a few years.