Medicines often prescribed for diabetes, inflammation and even one that treats osteoporosis in dogs, can also kill cancer cells in the laboratory, according to an exciting new study.
US researchers tested the cancer-fighting properties of more than 4500 non-cancer drugs and found that nearly 50 drugs typically used for other conditions also had some cancer-killing abilities.
Existing drugs were systematically analysed for anti-cancer capability – and the researchers discovered 49 medicines that not only neutralised cancer cells but left healthy cells unharmed.
“We found that a surprising number of non-oncology drugs are able to kill cancer cell lines in the lab,” said Dr Steven Corsello of Dana-Farber Cancer Institute and the Broad Institute of MIT and Harvard University.
Dr Corsello co-founded the MIT Broad Institute’s Drug Repurposing Hub. The ‘Hub’ is a repository for more than 6000 compounds – many of which are already approved by the US Federal Food & Drug Administration (FDA) and are available to consumers. It tests these drugs to see if some may prove to be effective in treating conditions not originally targeted by researchers and developers.
It can take a decade of lab work and clinical trials for a new drug to come on the market. The hub investigates whether drugs already shown to be safe for human consumption can be repurposed to treat other conditions.
The latest experiment used molecular barcoding technology called PRISM (profiling relative inhibition simultaneously in mixtures) to screen more than 4500 existing compounds against 578 different types of cancer cell lines.
It was the first time researchers screened the entire collection of mostly non-cancer drugs for their anti-cancer capabilities. The results were published in Nature Cancer.
“We tested 4518 compounds in this experiment in total,” said Dr Corsello. “We found 49 non-oncology drugs that were able to selectively kill cancer cell lines – killing some but not other cancers, which is an ideal property.
“We thought we’d be lucky if we found even a single compound with anti-cancer properties, but we were surprised to find so many,” said director of the Cancer Program at the Broad Institute Dr Todd Golub.
They found that some of the compounds killed cancer cells in unexpected ways.
“Most existing cancer drugs work by blocking proteins, but we’re finding that compounds can act through other mechanisms,” said Dr Corsello.
“We created the Repurposing Hub to enable researchers to make these kinds of serendipitous discoveries in a more deliberate way.
“In general, though, these kinds of discoveries are accidental.”
One of these ‘accidents’ involved the drug tepoxalin, originally developed for use in people but later approved for treating osteoarthritis in dogs, which also attacks a target called MDR1 which is expressed on the surface of cells and protects them from chemotherapy.
Patients who develop resistance to chemotherapy often have high levels of this protein.
Antabuse, a drug approved to treat alcohol dependence, may also attack a protein that commonly occurs in some breast cancers, while a compound originally developed to treat diabetes called vanadium, and levonorgestrel, a hormone used in contraceptives, also showed anti-cancer properties.
These drugs will now undergo further testing to better understand how they attacked and killed cancer cells.
“Our understanding of how these drugs kill cancer cells gives us a starting point for developing new therapies,” said Dr Corsello.
Does this study excite you? Do you think it’s possible that we could soon see more affordable cancer fighting medicines?
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