DMG, or diffuse midline glioma, is a rare and aggressive brain tumor that grows on the brain’s thalamus, pons, brainstem, cerebellum and spinal cord. Every year, between 200 to 400 children are diagnosed with DMG, and survival rate beyond five years is less than one percent. That is, until the Food and Drug Administration’s recent approval for the drug, Modeyso.
On Aug. 6, 2025, the FDA approved Jazz Pharmaceutical’s drug, Modeyso, which targets cancer cells directly to kill them. Modeyso helps to extend a patient’s life span, mitigate their symptoms and slowly eliminate the tumor.
What is DMG?
This fast-spreading tumor falls under the umbrella of diffuse intrinsic pontine glioma (DIPG), with glioma signaling a tumor that originates from the glial cells that support the central nervous system (CNS). The tumor is characterized by its ability to diffuse into surrounding healthy brain tissue through cerebrospinal fluid.
Most common in children and young adults, there is no known cause of DMG yet. However, scientists believe that since children ages 5 to 10 experience rapid brain development, their genes are most susceptible to errors in coding, as their genes are writing several instructions at a rapid pace. Genetic errors can lead to mutations, then to the development of tumors.
Researchers identified the mutation driving these tumors between 2012-2014, and the World Health Organization classified DMG in 2016. Having already been noted as an aggressive tumor prior to the official classification, researchers have been developing Modeyso, originally called ONC201, for years.
Symptoms of DMG
The tumor spreads very quickly, and is often only observed when it is too late. Some symptoms include fatigue, double vision, nausea, dizziness, seizures, trouble balancing, difficulty swallowing or speaking, tingling or numbness in the limbs and face, and loss of hearing and sight, as well as headaches, especially in the morning.
More severe symptoms, such as loss of hearing and ability to walk, tend to appear later on.
Upon identifying the symptoms, the next steps are using MRI and CT scans to identify the tumor. Then, targeted radiation therapy, and now, Modeyso, can be used to mitigate and remove the tumor from the CNS without requiring an operation.
About Modeyso
Modeyso targets the mitochondria of the cancer cell, since cancer cells have very high metabolic demands and rely heavily on the mitochondria for energy.
The drug stimulates the mitochondrial caseinolytic protease P enzyme to help break down critical mitochondrial proteins and leads to mitochondrial dysfunction, thus inducing the death of the tumor cells without harming the surrounding healthy cells.
The most popular form of the drug is a once-a-day pill, which can be prescribed to patients 1 year and older.
With developing Modeyso over the course of roughly 10-11 years, and since its FDA approval, Jazz Pharmaceuticals has begun its Phase III Action Trial to confirm clinical benefits. Modeyso is still being updated and is now being tested to see if it responds well to brain tumors outside of DMG.
Sandhya Kannan is an editorial assistant at CityScene Media Group. Feedback welcome at feedback@cityscenemediagroup.com
