A newly discovered enzyme may help better distinguish leukaemia patients responding to therapy from those that are not. 

Researchers from Goethe-University Frankfurt discovered the levels of a new biomarker, SAMHD1, would fluctuate in response to cell exposure to chemotherapy.

The study made use of cytarabine-resistant acut myeloid leukaemia (AML) cells from the Resistant Cancer Cell Line collection, run by both Prof Jindrich Cinatl, Goethe-University, and Prof Martin Michaelis, University of Canterbury, Kent.

The cells were exposed to cytarabine – a common first-line drug used to treat AML – whilst researchers kept an eye out for any particular proteins being affected.

The team discovered that the levels of the enzyme SAMHD1 would change dependent on the amount of cytarabine administered.

After initial findings, a consortium led by Cinatl found that SAMHD1 removes phosphate residues from the active form of cytarabine, reversing it into its inactive state and rendering the drug ineffective.

Further studies, led by Prof Hubert Serve of Goethe-University found that SAMHD1 was a highly accurate biomarker for predicting how well AML patients would respond to cytarabine-based therapies.

The team also found that inhibiting SAMHD1 would re-sensitise cytarabine-resistant AML cells to cytarabine-based chemotherapies, effectively reversing their resistance to the drug.

The findings could lead to screening methods using SAMHD1 as an indicator of whether cytarabine-based chemotherapy could be effective in AML patients, sparing those that are unlikely to respond any side effects.