Rare childhood central nervous system tumours have exposed one of the most stubborn weaknesses in modern oncology: science can move faster than the clinical-trial systems needed to test it. A new multi-stakeholder consensus published in the British Journal of Cancer proposes a strategic roadmap for making trials in these diseases more practical, more inclusive and more capable of producing meaningful answers. The paper, led by James Adamski, J. Robert Apps and S. Depani and developed with contributions from specialists across the research and care community, focuses on a problem that affects thousands of children worldwide but involves so many biologically distinct tumour types that conventional trial design often fails before recruitment even begins.
Childhood brain and spinal tumours are not a single disease. They include diffuse midline glioma, medulloblastoma, ependymoma, low-grade glioma and several rarer entities, each shaped by different genetic alterations, developmental origins and interactions with the surrounding nervous system. Even two tumours that look similar under a microscope may respond very differently to treatment because their molecular circuitry is distinct. Modern diagnosis increasingly depends on DNA methylation profiles, sequencing, copy-number changes and other molecular signatures, but this precision creates a statistical challenge: once patients are divided into biologically meaningful subgroups, each group may contain only a small number of children. Traditional randomised trials, designed for larger and more uniform populations, can therefore be slow, expensive and difficult to interpret.
The roadmap argues that the delivery of trials must be redesigned around the realities of rarity rather than forcing rare tumours into models created for common cancers. That means developing studies internationally from the beginning, using shared eligibility criteria, harmonised outcome measures and compatible laboratory methods. A child with a molecularly defined tumour may be eligible for only one specialised study anywhere in the world, making national recruitment strategies insufficient. Cross-border collaboration could enlarge the available patient population, reduce duplication and allow researchers to evaluate treatments across networks of specialist hospitals. The approach also requires early agreement among clinicians, scientists, regulators, funders and families about which questions matter most and what evidence will be considered strong enough to change practice.
One of the most important technical issues is the selection of trial endpoints. Overall survival remains essential, but it may take years to measure, particularly when children live with slow-growing tumours or when treatment can control disease without immediately eliminating it. Progression-free survival can be complicated by differences in imaging interpretation, treatment-related changes and the unique way paediatric tumours affect developing brains. The consensus therefore highlights the need for carefully validated measures that may include radiographic response, neurological function, cognitive development, quality of life and the ability to reduce long-term treatment damage. In children, a therapy that delays progression but causes severe learning, endocrine or neurological harm may not represent a meaningful success. A modern trial must measure the child’s future, not only the tumour’s present size.
The paper also reflects the growing influence of molecular classification on trial design. Instead of grouping patients solely by anatomical location or appearance, researchers can select participants according to alterations that drive tumour growth, such as changes in signalling pathways, chromatin regulation or DNA repair. This strategy can make a small trial more scientifically focused because every enrolled patient is selected for a biological reason. At the same time, it introduces the danger of creating extremely narrow studies that are impossible to complete. The proposed roadmap supports flexible designs capable of incorporating related molecular groups when they share a treatment vulnerability, while preserving enough biological precision to reveal who benefits and why. Such designs may be particularly valuable for targeted drugs, immunotherapies and combination treatments.
Adaptive and platform trials offer one possible solution. In a platform study, several therapies can be evaluated within a shared infrastructure, allowing ineffective options to be removed and promising ones to be added as evidence develops. Adaptive randomisation or pre-specified modifications can help researchers respond to emerging results without closing an entire programme and starting again. For rare paediatric tumours, this could reduce the time required to answer multiple questions and limit the number of children exposed to treatments that are unlikely to work. However, flexibility cannot replace rigorous statistics. Adaptive trials require strong data systems, transparent rules, independent oversight and agreement among regulators and participating institutions before recruitment begins. The consensus presents trial innovation as a practical necessity, but also stresses that methodological sophistication must serve reliability rather than simply produce faster headlines.
Access to high-quality biological material is another central challenge. Tumour tissue is difficult to obtain from children because surgery carries significant risks and because some lesions are located deep within the brain or spinal cord. Yet tissue may be needed to confirm a diagnosis, identify a treatment target and understand why a tumour becomes resistant. The roadmap points toward better coordination of tissue collection, processing and storage, alongside the use of less invasive technologies such as cerebrospinal-fluid analysis and circulating tumour DNA when scientifically validated. These liquid-biopsy approaches seek traces of tumour-derived genetic material in bodily fluids and could eventually allow clinicians to monitor molecular changes without repeated surgery. Their usefulness depends on sensitivity, standardisation and careful interpretation, because a negative sample does not necessarily mean that no tumour signal exists.
Families and young patients are positioned in the roadmap as partners in trial development rather than passive recipients of research. Travel to specialist centres, prolonged hospital stays, repeated scans, invasive procedures, financial pressure and disruption to schooling can determine whether participation is realistic. Consent and communication are also unusually complex when decisions involve parents, children and adolescents with different levels of understanding and autonomy. A trial that is technically elegant but inaccessible to families will fail to recruit the population it is intended to help. The consensus therefore supports earlier patient and public involvement, clearer explanations of risks and uncertainties, age-appropriate communication, and trial procedures designed around the daily lives of children. Patient-reported outcomes and family-reported outcomes can reveal benefits or harms that may not appear in laboratory data or scans.
The roadmap further addresses the infrastructure required after a trial has opened. Specialist paediatric centres need trained staff, molecular diagnostics, radiology expertise, pharmacy support and reliable coordination with laboratories and data teams. Funding must cover not only the experimental drug but also sequencing, sample shipping, imaging review, long-term follow-up and the coordination costs of international participation. Regulators and ethics committees may also need mechanisms for reviewing complex studies that involve multiple countries, changing treatment arms or rare molecular subgroups. Equally important is the creation of interoperable databases in which clinical, genomic, imaging and outcome data can be analysed together while protecting children’s privacy. Without sustained investment in this infrastructure, promising scientific discoveries may remain trapped in laboratories or be tested only in fragmented, underpowered studies.
The authors’ central message is that progress in rare childhood CNS tumours will depend on treating trial delivery as a scientific problem in its own right. Better drugs are essential, but they cannot transform care if studies recruit too slowly, measure the wrong outcomes or exclude the children most in need. A coordinated ecosystem linking families, hospitals, laboratories, charities, industry, regulators and international research groups could make small patient populations sufficient for decisive evidence. The new consensus does not offer a single therapy or promise an immediate cure; instead, it lays out how the field can become faster, fairer and more biologically precise. For children facing tumours that have long resisted conventional treatment, that organisational shift could be as important as the next breakthrough molecule.
Subject of Research: Delivery and design of clinical trials for rare childhood central nervous system tumours
Article Title: Strategic roadmap for delivery of clinical trials in rare childhood central nervous system (CNS) tumours: a multi-stakeholder consensus
Article References: Adamski, J., Apps, J.R., Depani, S. et al. Strategic roadmap for delivery of clinical trials in rare childhood central nervous system (CNS) tumours: a multi-stakeholder consensus. Br J Cancer (2026). https://doi.org/10.1038/s41416-026-03589-6
Image Credits: AI Generated
DOI: 10.1038/s41416-026-03589-6
Keywords: rare childhood tumours, central nervous system tumours, paediatric oncology, clinical trials, molecular classification, precision medicine, adaptive trials, brain tumours, patient involvement, international collaboration
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