Iron oxide (E172)

Iron oxide (E172) is a chemically synthesised substance that is authorised as a medicine and is being investigated as a contrast agent for magnetic resonance imaging (MRI). In the BRONTOSAURUS trial, it is being studied in people with glioblastoma, a type of brain tumour.^[1] The substance is also known as ultrasmall superparamagnetic iron oxide particles, or USPIO, in this research context.

What is iron oxide (E172)?

Iron oxide (E172) is a chemical substance that is authorised as a medicine. In the BRONTOSAURUS trial, it is being used in the form of ultrasmall superparamagnetic iron oxide particles, a type of iron-based nanoparticle that can be detected with MRI. The substance is given by intravascular use, meaning it is injected into the bloodstream. The trial record lists it as the test substance, meaning it is the active substance being investigated.^[1]

How does iron oxide (E172) work?

Iron oxide (E172) is being studied as an MRI contrast agent. The ultrasmall superparamagnetic iron oxide particles are designed to be taken up by certain cells in the body, which can then be seen more clearly on MRI scans. In the BRONTOSAURUS trial, the aim is to use these particles to visualise infiltrating tumour cells in glioblastoma, helping researchers see how far the tumour has spread into healthy brain tissue.^[1]

Which conditions is iron oxide (E172) used or studied for?

• Glioblastoma — a type of aggressive brain tumour. The BRONTOSAURUS trial is studying whether iron oxide (E172) can help visualise how glioblastoma infiltrates healthy brain tissue and predict regions of tumour recurrence.^[1]

How is iron oxide (E172) given?

Iron oxide (E172) is given by intravascular use, which means it is injected into the bloodstream. In the BRONTOSAURUS trial, the planned dose is 1 milligram per kilogram of body weight. The substance is prepared as a solution for injection.^[1]

What do the clinical trials show?

There is one clinical trial of iron oxide (E172) in the registry: the BRONTOSAURUS trial. This is a Phase 3, interventional study in glioblastoma.^[1] Phase 3 trials are typically larger studies that compare a new approach against the current standard of care, though this particular trial has a planned enrollment of 15 participants.

The trial is currently authorised, meaning it has received approval to begin recruiting participants. The primary outcome is to investigate the dosage of USPIO administration needed for adequate neuro-imaging, such as optimising the signal-to-noise ratio. Six healthy participants will be included for this initial imaging quality assessment, and the obtained images will be reviewed by a panel of radiologists to assess quality and diagnostic performance.^[1]

The broader research question is to what extent glioblastomas infiltrate healthy brain tissue and whether ultrasmall superparamagnetic iron oxide particles can be used to visualise co-opting infiltrating tumour cells, in an attempt to predict regions of tumour recurrence.^[1]

What side effects are known?

The registry record for the BRONTOSAURUS trial does not list specific side effects for iron oxide (E172). As with any injected substance, side effects may occur, but no data on side effects from this trial are available in the provided sources.