Pediatric diffuse hemispheric glioma H3 G34-mutant with gains of the BRAF locus: An illustrative case

Myeloid cells as potential targets for immunotherapy in pediatric gliomas

Pediatric high-grade glioma (pHGG) including pediatric glioblastoma (pGBM) are highly aggressive pediatric central nervous system (CNS) malignancies. pGBM comprises approximately 3% of all pediatric CNS malignancies and has a 5-year survival rate of approximately 20%. Surgical resection and chemoradiation are often the standard of care for pGBM and pHGG, however, even with these interventions, survival for children diagnosed with pGBM and pHGG remains poor. Due to shortcomings associated with the standard of care, many efforts have been made to create novel immunotherapeutic approaches targeted to these malignancies. These efforts include the use of vaccines, cell-based therapies, and immune-checkpoint inhibitors. However, it is believed that in many pediatric glioma patients an immunosuppressive tumor microenvironment (TME) possess barriers that limit the efficacy of immune-based therapies. One of these barriers includes the presence of immunosuppressive myeloid cells. In this review we will discuss the various types of myeloid cells present in the glioma TME, including macrophages and microglia, myeloid-derived suppressor cells, and dendritic cells, as well as the specific mechanisms these cells can employ to enable immunosuppression. Finally, we will highlight therapeutic strategies targeted to these cells that are aimed at impeding myeloid-cell derived immunosuppression.

A scoping review of diffuse hemispheric glioma, H3 G34-mutant: Epigenetic and molecular profiles, clinicopathology, and treatment avenues

Background

Survival of pediatric and young adults with malignant glioma remains poor despite progress in treatment. This is especially true for diffuse hemispheric glioma (DHG), H3 G34-mutant, which is often present in adolescent and young adult patients. This scoping review consolidates existing knowledge of DHG H3 G34-mutant and identifies future targets and therapeutic options. By streamlining this information, we aim to elucidate knowledge gaps in the field to better inform the community and motivate future research efforts.

Methods

In October 2024, MEDLINE, Embase, Cochrane Library, and Web of Science Core Collection were searched. Two reviewers screened all articles by title and abstract review and 3 independent reviewers extracted all studies meeting inclusion criteria relevant to H3G34R/V tumors (preclinical and clinical studies).

Results

Of the 2203 articles screened, 220 were deemed eligible (79 literature reviews, 7 systematic reviews, 63 preclinical studies, and 71 clinically oriented studies). We found that the United States and Acta Neuropathologica were the top country and journal contributors, respectively.

Conclusion

For this disease, it is critical to the field to conduct further research related to complexities of the tumor microenvironment, translation of preclinical studies to therapeutic early phase trials, and determining the role of targeted central nervous system drug delivery, so as to improve disease prognosis and survival.

Review on neuroimaging in pediatric-type diffuse low-grade gliomas

The fifth edition of the World Health Organization Classification of Tumors of the Central Nervous System (WHO CNS5) has identified a new classification system for tumors of the brain and spinal cord, highlighting the pivotal role of molecular diagnosis in accurately categorizing neoplasms. In addition to previous classifications, one of the key distinctions lies in categorizing pediatric-type diffuse low-grade gliomas (pDLGGs) and pediatric-type diffuse high-grade gliomas (pDHGGs) as distinct tumor types. Although similar in histology and morphology, pediatric diffuse gliomas are completely different from the adult type with respect to the molecular genetic characteristics, prognosis, and treatment strategies. pDLGG includes four tumor types, namely, diffuse astrocytoma, MYB- or MYBL1-altered; angiocentric glioma; polymorphous low-grade neuroepithelial tumor of the young (PLNTY); and diffuse low-grade glioma, MAPK pathway-altered, three types of which are newly recognized tumor types. Herein, we review the clinical characteristics, histopathological and molecular genetic characteristics, neuroimaging features, and prognosis of pDLGG and summarize the neuroimaging key points in diagnosing different tumor types. This review aims to evaluate and update the relevant pDLGG features and advances in neuroimaging that may assist in differential diagnosis, surgery planning, and prognostic determination of these tumor types and provide accurate diagnostic information for clinical colleagues.