Every year, around 25 children in the Netherlands are diagnosed with acute myeloid leukemia (AML), a form of blood cancer. Survival rates have improved in the last decades, and more than 70% of children now survive their disease. But the chemotherapy treatment can lead to long-term side effects, and smarter, kinder treatments are needed.
A type of DNA change that often occurs in childhood leukemia is a so-called fusion gene, which originates from two genes that are normally separate. Fusion genes drive the uncontrolled cell growth in many forms of childhood cancer. Such fusion genes do not occur in healthy cells, making them an excellent target for new, targeted treatment. But there is not yet a good way to reach fusion genes with medicines.
In a new study, scientists at the Princess Máxima Center for pediatric oncology and Newcastle University in the United Kingdom developed a way to successfully switch off an AML fusion gene by delivering a piece of biological code called siRNA into the bone marrow – the place where blood cells are made – in mice. Their study was published in the journal Leukaemia in February and supported by KiKa.
The team, led by research group leader prof. dr. Olaf Heidenreich, used an siRNA – which stops a gene from being turned into a protein – to target RUNX1/ETO, a fusion gene that occurs in the blood cells of children with leukemia. To make sure that the siRNA would get to its target, the scientists packaged it into tiny spheres called liquid nanoparticles.
By injecting the liquid nanoparticles with their siRNA cargo into mice with leukemia, the scientists were able to confirm that they arrived at their destination in the bone marrow. Importantly, they found that RUNX1/ETO was indeed switched off as intended. As a result, the growth of the leukemia cells in the mice was stopped, and the mice survived for longer.
‘While these are early results, I’m excited to see the promise of this targeted treatment approach,’ says Olaf Heidenreich, who led the study. ‘So far, we have seen liquid nanoparticles mainly being used in vaccines. But our new study shows that it could be an important drug delivery principle for targeted cancer treatment.
‘We found that we could deliver siRNA code into the bone marrow, where it could stop the growth of leukemia cells. But liquid nanoparticles can be applied more widely in childhood cancer. In future, they could be used in CAR-T immunotherapy for children with leukemia, tumor vaccination or for targeted treatment in solid tumors.’
The team is currently refining the particles and is testing them in leukemia cells obtained from children with AML, stored in the Máxima’s Biobank. Their work has also been expanded into a joint project with prof. dr. Irmela Jeremias within the Twinning Program with KiTZ in Heidelberg, Germany. If the particles also show promise in these studies, their benefit could in future be tested in a clinical trial.