Scientists are Developing a Pill to Diagnose Breast Cancer
Mammography is an imprecise tool — as many as one in three women treated for breast cancer undergo unnecessary procedures, and it’s no understatement to say that mammograms are notoriously uncomfortable.
A new method for diagnosing breast cancer involves a pill, which could do a better job distinguishing between benign and aggressive tumours.
Developed by researchers at the University of Michigan, the pill makes tumours light up when exposed to infrared light, and the concept has already been demonstrated to work in mice. Their work is published in Molecular Pharmaceutics.
“We overspend $4 billion per year on the diagnosis and treatment of cancers that women would never die from,” said Greg Thurber, University of Michigan assistant professor of chemical engineering and biomedical engineering, who led the team. “If we go to molecular imaging, we can see which tumours need to be treated.”
The move could also catch cancers that would have gone undetected. Thurber’s team uses a dye that responds to infrared light to tag a molecule commonly found on tumour cells, in the blood vessels that feed tumours and in inflamed tissue. By providing specific information on the types of molecules on the surface of the tumour cells, physicians can better distinguish a malignant cancer from a benign tumour.
Compared to visible light, infrared light penetrates the body easily — it can get to all depths of the breast without an X-ray’s tiny risk of disrupting DNA and seeding a new tumour. Using a dye delivered orally rather than directly into a vein also improves the safety of screening, as a few patients in 10,000 can have severe reactions to intravenous dyes. These small risks turn out to be significant when tens of millions of women are screened every year in the U.S. alone.
But it’s not easy to design a pill that can carry the dye to the tumour.
“To get a molecule absorbed into the bloodstream, it needs to be small and greasy. But an imaging agent needs to be larger and water-soluble. So you need exact opposite properties,” Thurber said.
Fortunately, they weren’t the only people looking for a molecule that could get from the digestive system to a tumour. The pharmaceutical company Merck was working on a new treatment for cancer and related diseases. They got as far as phase II clinical trials demonstrating its safety, but unfortunately, it wasn’t effective.
“It’s actually based on a failed drug,” Thurber said. “It binds to the target, but it doesn’t do anything, which makes it perfect for imaging.”
The targeting molecule has already been shown to make it through the stomach unscathed, and the liver also gives it a pass, so it can travel through the bloodstream. The team attached a molecule that fluoresces when it is struck with infrared light to this drug. Then, they gave the drug to mice that had breast cancer, and they saw the tumours light up.