US researchers have developed an enzyme could eliminate the damage that chemotherapy does to healthy tissue.

Treating cancer with chemotherapy can be as destructive to healthy cells as it is to tumour cells, causing notorious, debilitating side effects. US scientists have now developed an enzyme with the potential to eliminate the extreme fatigue, sickness and hair loss that result from this cell damage and strike fear into the hearts of cancer patients.

The researchers, led by Zaver Bhujwalla from Johns Hopkins University in Baltimore, developed a traceable enzyme to activate cancer prodrugs. The enzyme can be tracked on its journey within the body, to ensure that it has been cleared out of healthy tissue before the prodrug is introduced. 

’Blood vessels of tumour cells are much leakier than normal, healthy vasculature so the enzyme leaks into the tumour but is cleared out of healthy tissue by the bloodstream,’ Bhujwalla explained. 

The enzyme, cytosine deaminase was chemically tagged with two tracers, gadolinium, which is a contrast agent that can be visualised using magnetic resonance imaging (MRI); and rhodamine, which is an optically visible tracer. Using rhodamine allowed the researchers to view sections of tissue microscopically and verify that their MRI images were accurate. 

’This is the first time that a prodrug enzyme has been made visible with MRI,’ Bhujwalla told Chemistry World. ’It’s crucial because this type of imaging can be used in a clinical setting.’

Side-effect free chemotherapy is Bhujwalla’s ultimate aim and this research is a significant step towards that. Her team is continuing preclinical studies and their results have shown that none of the components of this prospective treatment regime are toxic to healthy cells. 

’This could allow scientists to work out exactly how effective different Enzyme/Prodrug techniques might be,’ said Henry Scowcroft from Cancer Research UK. ’As these methods are refined, they may one day be used to treat cancer patients with minimal side effects.

And, said lead researcher Bhujwalla, ’The same chemistry can also be applied to other enzymes for other prodrugs so this could be developed for many different types of anticancer drug.’

Victoria Gill