cns

ACTION is the first placebo-controlled phase 3 trial ever run in diffuse midline glioma, the childhood brain-stem tumour that radiotherapy alone has never cured. It asks whether taking dordaviprone after radiotherapy lengthens life.

IDH-mutant astrocytoma is the slow-growing form of adult glioma, defined by a mutation in the IDH1 or IDH2 gene that makes the tumour produce a chemical which rewires its own cells. Surgery first, and then either watchful waiting, the new pill vorasidenib, or radiotherapy with chemotherapy, depending on grade and how much tumour is left.

ATRT is an aggressive brain tumour of babies and toddlers caused by loss of a single gene, SMARCB1, part of the machinery that opens and closes DNA. Intensive chemotherapy with stem-cell rescue, and radiotherapy where age allows, now cure a meaningful share of children who once had little chance, and drugs aimed at the epigenetic consequence of SMARCB1 loss (EZH2 inhibitors) are in trials.

Brain metastases are cancers that have spread to the brain from elsewhere, most often from the lung, breast or skin. Focused radiation aimed at each spot (radiosurgery) has largely replaced radiation to the whole brain, and for some cancers modern targeted drugs and immunotherapy reach the brain well enough to shrink the deposits on their own.

Germ cell tumours of the brain grow near the pineal gland or above the pituitary in teenagers. The commonest kind, germinoma, is so sensitive to radiation and chemotherapy that most patients are cured; the other kinds need stronger chemotherapy and radiotherapy, and doctors measure two proteins in the blood and spinal fluid to tell them apart and to follow treatment.

This trial asked whether children with average-risk medulloblastoma could safely receive less radiation. Shrinking the boost to the tumour bed was safe; cutting the dose to the whole brain and spine in young children was not, so 23.4 Gy remains the floor for most.

Craniopharyngioma is a benign but destructive brain tumour growing from embryonic remnants beside the pituitary gland and hypothalamus. Surgery, or limited surgery plus radiotherapy, cures most people, but the price can be lifelong hormone deficiency and severe obesity. The adult (papillary) form carries a BRAF mutation and shrinks markedly with BRAF and MEK inhibitors, its first drug treatment.

Diffuse midline glioma grows through the brainstem and cannot be removed surgically. A single change in a histone protein (H3 K27M) rewires how the tumour reads its DNA. Radiotherapy was long the only help; in 2025 the first drug aimed at this tumour, dordaviprone (ONC201), was approved after durable shrinkage in some patients, and GD2 CAR-T cells have produced striking early responses.

Ependymomas grow from the cells lining the fluid spaces of the brain and spinal cord, mostly in children under five. Removing the whole tumour followed by focused radiotherapy controls most cases; molecular groups defined in 2021 behave differently, with posterior fossa group A relapsing often, and there is no approved drug.

FIREFLY-1 showed that a once-weekly pill, tovorafenib, shrinks most relapsed childhood low-grade gliomas driven by BRAF changes, including the common KIAA1549-BRAF fusion that older BRAF drugs could not treat safely. It led to the first approval of a drug for this disease.

Gliomas are now diagnosed by molecular class, and three classes got their first targeted drugs in 2024-25 (vorasidenib for IDH-mutant glioma, tovorafenib for BRAF-altered paediatric glioma, dordaviprone for H3 K27M). Glioblastoma itself is the hardest to treat and has kept the same standard since 2005; CAR-T delivered into the brain and focused-ultrasound drug delivery are the live directions.

Group 3 and group 4 medulloblastoma are the two commonest forms of this cerebellar brain tumour and the ones without a druggable driver. Group 3 strikes young children, often with extra copies of MYC and spread through the spinal fluid; group 4 affects older boys. Both get surgery, craniospinal radiotherapy and chemotherapy; trials showed the radiation dose cannot be cut for young children.

Medulloblastoma is the most common malignant childhood brain tumour, arising in the cerebellum. Surgery, radiation to the whole brain and spine, and chemotherapy cure about 70%, at a heavy cost to thinking and growth; treatment is now being tailored to four molecular subgroups so that the low-risk children get less.

Meningiomas grow from the membranes covering the brain and spinal cord rather than from the brain itself. Most are slow and benign and are either watched or removed; radiotherapy or radiosurgery treats what surgery cannot reach or what grows back, and no drug has yet been approved for them.

Oligodendroglioma is the adult brain tumour most responsive to chemotherapy. It is recognised by an IDH mutation together with loss of parts of chromosomes 1 and 19, and after surgery it is treated with radiotherapy plus the PCV drug combination, or, for small grade 2 tumours, with vorasidenib or watchful waiting.

High-grade gliomas in children look like adult glioblastoma under the microscope but are driven by different genes, so they are now classified separately. Surgery and radiotherapy remain the mainstay and chemotherapy adds little; the real gains are in small subsets with a targetable gene change, such as BRAF V600E tumours and the fusion-driven tumours of infants.

Paediatric low-grade gliomas are slow-growing brain tumours driven almost always by a single overactive signal, the MAPK pathway, most often through a BRAF gene change. Because the switch is known, pills that block it (dabrafenib with trametinib, and tovorafenib) now shrink tumours far more often than chemotherapy, and children are increasingly spared radiation to the developing brain.

Pituitary tumours are usually benign growths of the hormone gland at the base of the brain that cause trouble by overproducing hormones or pressing on the optic nerves. Prolactin-producing tumours melt away with a tablet, most others are cured by surgery through the nose, and the rare aggressive ones respond to the chemotherapy drug temozolomide.

Primary CNS lymphoma is a lymphoma confined to the brain, eyes and spinal fluid. Unlike most brain tumours it is chemo-sensitive: high-dose methotrexate-based treatment cures a substantial minority, and consolidation with a stem-cell transplant has replaced whole-brain radiation for the fit.

SHH-activated medulloblastoma is driven by the sonic hedgehog growth pathway, the signal that normally tells the developing cerebellum to grow. In infants it is often cured with chemotherapy alone and no radiotherapy; in adults it responds for a time to hedgehog-blocking pills such as vismodegib; and when it carries a TP53 mutation in an older child, often inherited, it resists everything.

Tumours inside or around the spinal cord are rare and usually slow growing, but they press on the cord and threaten walking and bladder control. Most are removed by a surgeon watching nerve signals during the operation; radiotherapy is used when a tumour cannot be fully removed or is high grade, and there are few drugs.

The first randomised trial to show that a targeted drug pair beats chemotherapy in children with a brain tumour. Children whose low-grade glioma carries a BRAF V600 mutation had far more tumour shrinkage and a much longer time before progression on dabrafenib plus trametinib than on standard carboplatin and vincristine.

A vestibular schwannoma is a benign brain tumour, a growth on the balance and hearing nerve, deep in the skull. It is rarely dangerous, so many are simply watched with scans; growing tumours are treated with either an operation or a single precisely focused dose of radiation, and people with the inherited condition NF2, who develop tumours on both sides, can be helped by the drug bevacizumab.

WNT-activated medulloblastoma is the rarest and most curable of the four molecular groups of medulloblastoma, a brain tumour of the cerebellum. It is driven by a mutation in the beta-catenin gene that switches the WNT growth pathway on. Almost every child is cured with standard therapy, so current trials are asking how much radiotherapy and chemotherapy can be taken away.