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High-grade gliomas in infants
Source: Childhood Cancer Genomics (PDQ®)–Health Professional Version, National Cancer Institute.
Source updated: April 30, 2025 · Captured 2026-09-09.
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Infants and young children with high-grade gliomas appear to have tumors with distinctive molecular characteristics [19,20] when compared with tumors of older children and adults with high-grade gliomas. An indication of this difference was noted with the application of DNA methylation analysis to pediatric high-grade tumors, which found that approximately 7% of pediatric patients with a histological diagnosis of high-grade glioma had tumors with methylation patterns more closely resembling those of low-grade gliomas.[10] Ten of 16 infants (younger than 1 year) with a high-grade glioma diagnosis were in this methylation array–defined group.[10] The 5-year survival rate for patients in this report diagnosed at younger than 1 year exceeded 60%, while the 5-year survival rate for patients aged 1 to 3 years and older was less than 20%.
Two studies of the molecular characteristics of high-grade gliomas in infants and young children have further defined the distinctive nature of tumors arising in children younger than 1 year. A key finding from both studies is the importance of gene fusions involving tyrosine kinases (e.g., ALK, NTRK1, NTRK2, NTRK3, and ROS1) in patients in this age group. Both studies also found that infants with high-grade gliomas whose tumors have these gene fusions have survival rates much higher than those of older children with high-grade gliomas.[19,20]
The first study presented data for 118 children younger than 1 year with a low-grade or high-grade glioma diagnosis who had tumor tissue available for genomic characterization.[19] Approximately 75% of the cases were classified as low grade, but the diminished utility of histological classification in this age group was illustrated by the relatively low OS rate for the low-grade cohort (71%) and the relatively favorable survival for the high-grade cohort (55%). Rates of surgical resection were higher for patients with high-grade tumors, a result of many of the low-grade tumors occurring in midline locations while the high-grade tumors were found in supratentorial locations. This finding may also help to explain the relative outcomes for the two groups. Genomic characterization divided the infant glioma population into the following three groups, the first of which included patients with high-grade gliomas:
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Group 1 tumors were receptor tyrosine kinase driven and primarily high grade (83%). These tumors harbored lesions in ALK, ROS1, NTRK, and MET. The median age at diagnosis was 3 months, and OS rates were approximately 60%.
Group 2 tumors were RAS/MAPK driven and were all hemispheric low-grade gliomas, representing one-fourth of hemispheric gliomas in infants. BRAF V600E was the most common alteration, followed by FGFR1 alterations and BRAF fusions. This group had a median age at presentation of 8 months and had the most favorable outcome (10-year OS rate, 93%).
Group 3 tumors were RAS/MAPK driven with low-grade histology and midline presentation (approximately 80% optic pathway/hypothalamic gliomas). Most group 3 tumors showed either BRAF fusions or BRAF V600E. Median age at diagnosis was 7.5 months. The 5-year progression-free survival (PFS) rate was approximately 20%, and the 10-year OS rate was approximately 50% (far inferior to that of optic pathway/hypothalamic gliomas in children aged >1 year).
The second study focused on tumors from children younger than 4 years with a pathological diagnosis of WHO grades 2, 3, and 4 gliomas, astrocytomas, or glioneuronal tumors. Among the 191 tumors studied that met inclusion criteria, 61 had methylation profiles consistent with glioma subtypes that occur in older children (e.g., IDH1, diffuse midline glioma H3 K27-altered, SEGA, pleomorphic xanthoastrocytoma, etc.). The remaining 130 cases were called the intrinsic set and were the focus of additional molecular characterization:[20]
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The intrinsic set contained most of the patients diagnosed before age 1 year (49 of 63 patients, 78%) and had a median age of 7.2 months. Tumors were frequently in a superficial hemispheric location, often involving the meninges, and had a well-defined border with adjacent normal brain.
The methylation classifier placed most of these cases in either the desmoplastic infantile ganglioglioma/astrocytoma (DIG/DIA) subgroup or in the infantile hemispheric glioma subgroup.
For 41 tumors from the intrinsic set in which tissue was available for gene panel and RNA sequencing, 25 tumors had fusions involving either ALK (n = 10), NTRK1 (n = 2), NTRK2 (n = 2), NTRK3 (n = 8), ROS1 (n = 2), or MET (n = 1). BRAF variants (n = 3) were observed in cases that were high scoring by methylation array for the DIG/DIA or DIG/DIA-like subgroups.
For patients in the intrinsic set, the 5-year survival rate was higher for patients whose tumors had gene fusions when compared with patients whose tumors lacked fusions (approximately 80% vs. 60%, respectively). However, both of these groups of patients had much higher survival rates than other children with high-grade gliomas.
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