Childs Nerv Syst. 2023 May 11. doi: 10.1007/s00381-023-05976-3. Online ahead of print.

ABSTRACT

Pontine gliomas represent difficult to treat entity due to the location and heterogeneous biology varying from indolent low-grade gliomas to aggressive diffuse intrinsic pontine glioma (DIPG). Making the correct tumor diagnosis in the pontine location is thus critical. Here, we report a case study of a 14-month-old patient initially diagnosed as histone H3 wild-type DIPG. Due to the low age of the patient, the MRI appearance of DIPG, and anaplastic astrocytoma histology, intensive chemotherapy based on the HIT-SKK protocol with vinblastine maintenance chemotherapy was administered. Rapid clinical improvement and radiological regression of the tumor were observed with nearly complete remission with durable effect and excellent clinical condition more than 6.5 years after diagnosis. Based on this unexpected therapeutic outcome, genome-wide DNA methylation array was employed and the sample was classified into the methylation class "Low-grade glioma, MYB(L1) altered." Additionally, RT-PCR revealed the presence of MYB::QKI fusion. Taken together, the histopathological classification, molecular-genetic and epigenetic features, clinical behavior, and pontine location have led us to reclassify the tumor as a pontine MYB-altered glioma. Our case demonstrates that more intensive chemotherapy can achieve long-term clinical effect in the treatment of MYB-altered pontine gliomas compared to previously used LGG-based regimens or radiotherapy. It also emphasizes the importance of a biopsy and a thorough molecular investigation of pontine lesions.

PMID:37165121 | DOI:10.1007/s00381-023-05976-3

Brain Tumor Res Treat. 2023 Apr;11(2):79-85. doi: 10.14791/btrt.2022.0041.

ABSTRACT

Diffuse intrinsic pontine gliomas (DIPGs) account for 10%-20% of all central nervous system tumors in children and are the leading cause of death in children with brain tumors. Although many clinical trials have been conducted over the past decades, the survival outcome has remained unchanged. Over 90% of children die within 2 years of the diagnosis, and radiotherapy remains the standard treatment to date. To improve the prognosis, hyperfractionated and hypofractionated radiotherapy and/or addition of radiosensitizers have been investigated. However, none of the radiotherapy approaches have shown a survival benefit, and the overall survival of patients with DIPG is approximately 11 months. Here, we comprehensively review the management of DIPG with focus on radiotherapy.

PMID:37151149 | PMC:PMC10172015 | DOI:10.14791/btrt.2022.0041

Brain Tumor Res Treat. 2023 Apr;11(2):86-93. doi: 10.14791/btrt.2023.0011.

ABSTRACT

Diffuse midline glioma (DMG), hitherto known as diffuse intrinsic pontine glioma (DIPG), is a rare and aggressive form of brain cancer that primarily affects children. Although the exact cause of DMG/DIPG is not known, a large proportion of DMG/DIPG tumors harbor mutations in the gene encoding the histone H3 protein, specifically the H3K27M mutation. This mutation decreases the level of H3K27me3, a histone modification that plays a vital role in regulating gene expression through epigenetic regulation. The mutation also alters the function of polycomb repressive complex 2 (PRC2), thereby preventing the repression of genes associated with cancer development. The decrease in H3K27me3 caused by the histone H3 mutation is accompanied by an increase in the level of H3K27ac, a post-translational modification related to active transcription. Dysregulation of histone modification markedly affects gene expression, contributing to cancer development and progression by promoting uncontrolled cell proliferation, tumor growth, and metabolism. DMG/DIPG alters the metabolism of methionine and the tricarboxylic acid cycle, as well as glucose and glutamine uptake. The role of epigenetic and metabolic changes in the development of DMG/DIPG has been studied extensively, and understanding these changes is critical to developing therapies targeting these pathways. Studies are currently underway to identify new therapeutic targets for DMG/DIPG, which may lead to the development of effective treatments for this devastating disease.

PMID:37151150 | PMC:PMC10172016 | DOI:10.14791/btrt.2023.0011

Neurooncol Adv. 2023 May 4;5(1):vdad024. doi: 10.1093/noajnl/vdad024. eCollection 2023 Jan-Dec.

ABSTRACT

BACKGROUND: Diffuse intrinsic pontine glioma (DIPG) and other diffuse midline gliomas (DMG) of the thalamus and spinal cord are rare but devastating high-grade glial tumors of childhood with no curative treatment. Despite aggressive treatment attempts the prognosis has remained poor. Chimeric antigen receptor (CAR) T cell therapy has been identified as a promising new approach in the treatment of DMG tumors; however, additional targets are urgently required given known tumor heterogeneity and the prospect of antigen escape of this cancer.

METHODS: Using cell surface mass spectrometry, we detected high HER2 cell surface protein across a panel of patient-derived DIPG cells, thereby identifying an existing CAR T cell therapy for use in DIPG. Primary human T cells were transduced to express a second-generation HER2 CAR and interrogated for efficacy against patient-derived DIPG cells.

RESULTS: HER2 CAR T cells demonstrated potent and antigen-specific cytotoxicity and cytokine secretion when co-cultured with patient-derived DIPG cells. Furthermore, HER2 CAR T cells provided a significant regression in intracranial DIPG xenograft tumors.

CONCLUSIONS: HER2 CAR T cells are already in clinic development and are well tolerated in pediatric patients. Here we provide strong preclinical evidence for the inclusion of DIPG patients in future pediatric CNS tumor HER2 CAR T cell clinical trials.

PMID:37152812 | PMC:PMC10158089 | DOI:10.1093/noajnl/vdad024

Cancer Res. 2023 May 5:CAN-23-0186. doi: 10.1158/0008-5472.CAN-23-0186. Online ahead of print.

ABSTRACT

Diffuse midline gliomas (DMG), including diffuse intrinsic pontine gliomas (DIPGs), are the most lethal of childhood cancers. Palliative radiotherapy is the only established treatment, with median patient survival of 9-11 months. ONC201 is a DRD2 antagonist and ClpP agonist that has shown preclinical and emerging clinical efficacy in DMG. However, further work is needed to identify the mechanisms of response of DIPGs to ONC201 treatment and to determine whether recurring genomic features influence response. Using a systems-biological approach, we showed that ONC201 elicits potent agonism of the mitochondrial protease ClpP to drive proteolysis of electron transport chain and tricarboxylic acid cycle proteins. DIPGs harboring PIK3CA-mutations showed increased sensitivity to ONC201, while those harboring TP53-mutations were more resistant. Metabolic adaptation and reduced sensitivity to ONC201 was promoted by redox-activated PI3K/Akt signaling, which could be counteracted using the brain penetrant PI3K/Akt inhibitor, paxalisib. Together, these discoveries coupled with the powerful anti-DIPG/DMG pharmacokinetic and pharmacodynamic properties of ONC201 and paxalisib have provided the rationale for the ongoing DIPG/DMG phase II combination clinical trial NCT05009992.

PMID:37145169 | DOI:10.1158/0008-5472.CAN-23-0186

Cancer Metastasis Rev. 2023 Apr 29. doi: 10.1007/s10555-023-10105-2. Online ahead of print.

ABSTRACT

Recurrent, clonal somatic mutations in histone H3 are molecular hallmarks that distinguish the genetic mechanisms underlying pediatric and adult high-grade glioma (HGG), define biological subgroups of diffuse glioma, and highlight connections between cancer, development, and epigenetics. These oncogenic mutations in histones, now termed "oncohistones", were discovered through genome-wide sequencing of pediatric diffuse high-grade glioma. Up to 80% of diffuse midline glioma (DMG), including diffuse intrinsic pontine glioma (DIPG) and diffuse glioma arising in other midline structures including thalamus or spinal cord, contain histone H3 lysine 27 to methionine (K27M) mutations or, rarely, other alterations that result in a depletion of H3K27me3 similar to that induced by H3 K27M. This subgroup of glioma is now defined as diffuse midline glioma, H3K27-altered. In contrast, histone H3 Gly34Arg/Val (G34R/V) mutations are found in approximately 30% of diffuse glioma arising in the cerebral hemispheres of older adolescents and young adults, now classified as diffuse hemispheric glioma, H3G34-mutant. Here, we review how oncohistones modulate the epigenome and discuss the mutational landscape and invasive properties of histone mutant HGGs of childhood. The distinct mechanisms through which oncohistones and other mutations rewrite the epigenetic landscape provide novel insights into development and tumorigenesis and may present unique vulnerabilities for pHGGs. Lessons learned from these rare incurable brain tumors of childhood may have broader implications for cancer, as additional high- and low-frequency oncohistone mutations have been identified in other tumor types.

PMID:37119408 | DOI:10.1007/s10555-023-10105-2