Australasian Science: Australia's authority on science since 1938

Anti-Nausea Drug Fights Tumours

By Stephen Luntz

A drug used to fight nausea associated with chemotherapy also reduces brain tumours, both in vitro and in mouse models.

Dr Elizabeth Harford-Wright of the University of Adelaide’s Centre for Neuroscience Research is investigating the link between the peptide substance P and brain tumours. Substance P is released by the nervous system and has a role in tissue swelling after injury, as well as a connection to depression and anxiety.

“Researchers have known for some time that levels of substance P are also greatly increased in different tumour types around the body,” says Harford-Wright. “We wanted to know if these elevated levels of the peptide were also present in brain tumour cells and, if so, whether or not they were affecting tumour growth. Importantly, we wanted to see if we could stop tumour growth by blocking substance P.”

Substance P is also involved in the emetic pathway that leads to vomiting, for which the drug Emend® is prescribed. In both tumours and nausea, substance P binds to the NK1 receptor but by binding to the same receptor Emend® prevents substance P from finding a spot to dock.

Harford-Wright tried applying Emend® to tumours. “We were successful in blocking substance P from binding to the NK1 receptor, which resulted in a reduction in brain tumour growth – and it also caused cell death in the tumour cells,” Harford-Wright says. “So preventing the actions of substance P from carrying out its role in brain tumours actually halted the growth of brain cancer.”

Substance P was elevated in all primary and secondary brain cancers Harford-Wright investigated, but the mouse studies were only conducted on melanoma tumours.

Substance P has so many roles in the body that some side-effects are likely if it is blocked. However, Harford-Wright says the levels in tumours are greatly elevated compared with the concentrations in most cases. She is not aware of any studies investigating whether chemotherapy patients taking Emend® have a better prognosis for brain cancers or other tumours.

Since Emend® already has regulatory approval for nausea treatment it should be easier to demonstrate its safety as a drug for brain cancer. Nevertheless Harford-Wright says “we’re not in discussion with anyone” about trials. Astonishingly Merck, which manufactures Emend®, has made no contact with Harford-Wright.