The geneticists from Trinity College Dublin have found how a specific genetic mutation called H3K27M causes the cancer, known as diffuse midline glioma (DMG).
In lab studies they have been able to successfully reverse its effects to slow cancer cell growth with a targeted drug.
Their far-reaching work, published in leading international journal Nature Genetics and supported by Worldwide Cancer Research and The Brain Tumour Charity, provides key insight into the genetics of DMG progression.
It holds out the chance of a highly promising, targeted therapeutic approach and offers hope of improved treatments in the future.
The scientists now call for clinical trials to begin imminently, in which an already approved class of drugs called 'EZH2 inhibitors' can be assessed.
These drugs target the same key biological pathway involved in DMG as they do successfully in lymphomas and sarcomas - two cancers which are common in adults.
Adrian Bracken, Professor in Trinity's School of Genetics and Microbiology who led the research, said: "We've taken a huge step forward in our study of DMG tumours and hope that the insights will help us design and implement precision oncology-based treatment approaches in DMG patients in the future.
"Crucially, EZH2 inhibitor drugs have already received approval from the United States Food and Drug Administration for the treatment of two types of adult cancer.
"We propose these drugs could be impactful for children with DMG and, as a result, call for clinical trials to begin next.
"Ultimately, we hope that our work - together with that of others focused in this area - will lead to curative clinical approaches for what is a truly terrible disease that can devastate families and for which there are currently no therapeutic options."
Dr Jane Pears, paediatric consultant oncologist at Our Lady's Children's Hospital, Crumlin, who treats children with this disease, said that "despite combined best efforts, these tumours remain a devastating diagnosis for children and their families".
"The best treatment we can currently offer may extend survival for a few months, but is not curative," she added.
"We are now entering an exciting era of expansion of our knowledge of this disease at a molecular level, which in turn will lead us towards more targeted treatments.
"Thanks to collaborative translational efforts between scientists such as Prof Bracken and his team and doctors in the clinical setting, this will hopefully lead to the improved outcomes that we all so dearly wish to see."