What is Diffuse Midline Glioma?
Diffuse Midline Glioma is a rare but highly aggressive tumour classified as World Health Organisation (WHO) grade 4. It usually affects children, though adults can develop it too. Because this tumour grows quickly and resists treatment, doctors focus on helping patients live as well as possible. Care often involves a team of specialists who work together to ease symptoms and support quality of life.
Diffuse Midline Glioma or DMG arises from glial cells, mainly astrocytes, in the central nervous system (CNS). Glial cells normally support the brain and spinal cord, but when they mutate, they may form tumours. As the name suggests, DMGs grow in midline structures of the CNS, including the thalamus, brain stem, and spinal cord. Because these tumours spread diffusely and infiltrate critical regions rather than forming a single mass, doctors rarely treat them with surgery. Since these tumours are aggressive in nature and classified as WHO grade 4 glioma, they are called Diffuse Midline Glioma.
Is DMG the same as DIPG?
Diffuse intrinsic pontine glioma (DIPG) is an aggressive tumour of the brainstem and accounts for approximately 70–80% of brainstem tumours in children. The median survival for DIPG remains less than one year despite decades of clinical trials. The H3K27M mutation is identified in around 80% of cases.
DIPG is now considered part of a broader category classified as DMG, H3 K27-altered, according to the World Health Organization reclassification. As the name suggests, DIPG is an infiltrative tumour that arises from glial cells and grows within the pons. While DIPG and DMG are closely related and often discussed together, DIPG refers specifically to the tumour’s anatomical location in the pons, whereas DMG is defined by its molecular characteristics.
Who does DMG affect
DMG most commonly occurs in children between 3 and 10 years of age, while DIPG, (now classified under DMG, H3 K27-altered) typically occurs in children aged 6–7 years.
These tumours typically arise in midline structures of the brain, most commonly the pons. While the exact reason for this age distribution is not fully understood, it is thought to be related to developmental and cellular processes that occurs in the brain during early childhood. As a result, DMG is less common in older children and adults.
Diffuse Midline Glioma Symptoms
Symptoms of diffuse midline glioma (DMG) are largely determined by the location of tumour growth. Because DMG typically arises in midline structures of the brain, symptoms are related to the functions controlled by the affected region. For example, brainstem gliomas, particularly those in the pons, may disrupt vital functions such as breathing, swallowing, and motor coordination. Tumours in the thalamus may affect memory, attention, and sensory processing, while spinal cord involvement may lead to weakness and bladder dysfunction.
Common symptoms to look out for include:
- Headache and nausea, often due to increased intracranial pressure
- Seizures, which may be focal or generalised
- Poor motor control, including difficulty walking, muscle weakness or paralysis on one side of the body
- Speech and swallowing difficulties, including trouble finding the right words
- Neurocognitive changes, such as memory impairment, attention deficits, and behavioural changes
- Visual disturbances, including blurred or loss of vision; hearing difficulties may also occur depending on tumour location
Diffuse Midline Glioma Treatment Options
Due to the aggressive nature of DMG, treatment options remain limited. The tumour’s delicate location and highly infiltrative behaviour make surgery difficult. When DMG grows in the pons, a region that controls breathing, swallowing, and blood pressure, surgery carries a high risk of damaging critical structures.
Chemotherapy and targeted therapies also show limited effectiveness. The blood–brain barrier restricts drug penetration, and efflux pumps actively remove many agents from the brain, reducing their therapeutic impact. In addition, tumour cells may develop resistance over time, which further limits the benefit of these treatments.
As a result, radiotherapy remains the main treatment option, although its effectiveness is limited. It is considered the standard of care but is largely palliative, as it helps slow tumour progression and prolong survival rather than cure the disease. Clinicians carefully plan radiation fields to target the tumour while minimising damage to surrounding critical brain structures. However, tumour cells can develop resistance to radiotherapy over time, and recurrence is common.
Despite these challenges, radiotherapy still provides meaningful, though temporary, tumour control. To improve outcomes, researchers continue to explore ways to enhance its effectiveness. Some patients may receive hypofractionated radiotherapy, which shortens treatment duration and may benefit younger patients.
Diffuse Midline Glioma Prognosis and Outlook
The prognosis for DMG depends on several factors, including the patient’s age, the extent of surgical resection (if surgery is performed), the tumour’s genetic profile and mutations, how well the tumour responds to treatment, and the degree of infiltration into nearby structures or spread from the primary site. DMGs that carry the H3K27M mutation typically have a poorer prognosis compared to other subtypes.
Younger patients may sometimes have a slightly better prognosis; however, outcomes still depend largely on the tumour’s molecular characteristics.
Because of the tumour’s critical location, surgery rarely achieves complete removal, which contributes to poorer outcomes and limits the effectiveness of other treatments such as radiotherapy.
As a result, treatment for DMG focuses on prolonging survival and relieving symptoms rather than achieving a cure. Patients who receive treatment may experience a modest improvement in survival, often measured in months, although outcomes vary depending on the factors mentioned above. The primary goal of the healthcare team is to maintain quality of life and provide supportive care throughout the disease course.
Research, Clinical Trials, and Hope for the Future
Due to the poor response of DMG to current treatments, and the limited role of surgery and chemotherapy in the standard of care, research exploring more effective therapies has become critically important in the DMG field. Chemotherapy is rarely effective against DMG, making radiotherapy the current standard of care. Therefore, efforts to optimise radiotherapy and combine it with other treatment approaches are actively being investigated. Re-irradiation combined with immune checkpoint inhibitors has shown a survival benefit in patients with recurrent DIPG.
The BIOMEDE 1.0 trial, a major international study in paediatric DIPG, aims to perform molecular profiling of tumour biopsies to guide targeted therapies. In this trial, a 6-year-old boy has remained tumour free for over six years, despite the disease typically being fatal within a year. The study introduced the targeted therapy everolimus in combination with radiotherapy and demonstrated its potential effectiveness, highlighting the importance of biopsy in guiding personalised treatment for DMG. Following this, the BIOMEDE 2.0 trial is currently underway to evaluate the efficacy of ONC201 in comparison with everolimus.
Tumour Treating Fields (TTFields) is a non-invasive anti-cancer treatment that uses alternating electric fields to disrupt the proliferative ability of cancer cells. TTFields have also been shown to enhance chemotherapy sensitivity. Combining temozolomide with TTFields has demonstrated a significant prolongation of overall survival in a patient with DMG.
In 2025, the FDA granted accelerated approval to dordaviprone (ONC201, also known as Modeyso) for the treatment of recurrent DMG in adults and children aged one year and older, making it the first systemic therapy approved specifically for DMG.
Safer biopsy techniques, including liquid biopsies, are emerging as a promising approach for identifying H3K27M mutations in DMG. It can also be used to monitor treatment response over time.
Immunotherapy approaches, including CAR T-cell therapy, vaccine therapy, oncolytic viral therapy, and cytokine-based treatments, have shown promising results in clinical trials involving patients with H3K27M-mutant DMG.
Support for families and carers
A diagnosis of diffuse midline glioma (DMG) affects the whole family, not just the person diagnosed. Parents, carers and siblings often find themselves navigating complex medical decisions while coping with fear, uncertainty and grief.
Support may include help understanding treatment options, coordinating care, managing practical challenges, and finding emotional support for the months ahead. Many families also need guidance in accessing second opinions, clinical trials, or palliative care services — and in knowing when to ask for help.
You do not have to manage this alone. Connecting with experienced support services like the National Advocacy Service can help connect you with information, resources and support tailored to your situation.
Visit our Support Hub for more information.
Disclaimer: All Cure Brain Cancer Foundation website content is created and published online for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. You should seek your own medical advice from your doctor or other qualified health professionals.
References
- https://www.cancer.gov/rare-brain-spine-tumor/tumors/diffuse-midline-gliomas
- Al Sharie, S., Abu Laban, D., & Al-Hussaini, M. (2023, Oct 6). Decoding Diffuse Midline Gliomas: A Comprehensive Review of Pathogenesis, Diagnosis and Treatment. Cancers (Basel), 15(19). https://doi.org/10.3390/cancers15194869
- Jovanovich, N., Habib, A., Head, J., Hameed, F., Agnihotri, S., & Zinn, P. O. (2023). Pediatric diffuse midline glioma: Understanding the mechanisms and assessing the next generation of personalized therapeutics. Neuro-Oncology Advances, 5(1), vdad040. https://doi.org/10.1093/noajnl/vdad040
- Noon, A., & Galban, S. (2023, 2023/06/01/). Therapeutic avenues for targeting treatment challenges of diffuse midline gliomas. Neoplasia, 40, 100899. https://doi.org/https://doi.org/10.1016/j.neo.2023.100899
- Tosi, U., & Souweidane, M. (2024, Jan 2). Diffuse Midline Gliomas: Challenges and New Strategies in a Changing Clinical Landscape. Cancers (Basel), 16(1). https://doi.org/10.3390/cancers16010219
- Yang, Z., Sun, L., Chen, H., Sun, C., & Xia, L. (2024, 2024/01/30/). New progress in the treatment of diffuse midline glioma with H3K27M alteration. Heliyon, 10(2), e24877. https://doi.org/https://doi.org/10.1016/j.heliyon.2024.e24877