Researchers from the University of Texas at Austin found that thiabendazole, an FDA-approved, generic drug destroys newly established blood vessels, making it a vascular disrupting agent.
Inhibiting blood vessel, or vascular, growth can be an important chemotherapeutic tool because it starves tumours.
Tumours induce new blood vessel formation to feed their out-of-control growth.
In trials using mice, the researchers found that thiabendazole decreased blood vessel growth in fibrosarcoma tumours by more than a half.
Fibrosarcomas are cancers of the connective tissue, and they are generally heavily vascularised with blood vessels.
The drug also slowed tumour growth.
"This is very exciting to us, because in a way we stumbled into discovering the first human-approved vascular disrupting agent," Edward Marcotte, professor of chemistry, said.
"Our research suggests that thiabendazole could probably be used clinically in combination with other chemotherapies," Marcotte said in a statement.
Hye Ji Cha, another researcher tested thiabendazole in developing frog embryos. These are fast growing vertebrates in which scientists can watch blood vessel growth in living animals.
Cha found that frog embryos grown in water with the drug either didn't grow blood vessels or grew blood vessels that were then dissolved away by the drug.
When the drug was removed, the embryos' blood vessels grew back.
The drug was then tested on human blood vessel cells growing in Petri dishes, the study found that the drug also inhibited their growth.
Finally, it was tested on fibrosarcoma tumours in mice and it reduced blood vessel growth in the tumours as well as slowed the tumours' growth.
"We hope the clinical trials will be easier because it is already approved by the FDA for human use," Marcotte said.
The study was published in the journal PLOS Biology.