Chimeric antigen receptor adoptive immunotherapy in central nervous system tumors: state of the art on clinical trials, challenges, and emerging strategies to addressing them.

PURPOSE OF REVIEW: Central nervous system (CNS) tumors represent a significant unmet medical need due to their enduring burden of high mortality and morbidity. Chimeric antigen receptor (CAR) T-cell therapy emerges as a groundbreaking approach, offering hope for improved treatment outcomes. However, despite its successes in hematological malignancies, its efficacy in solid tumors, including CNS tumors, remains limited. Challenges such as the intricate tumor microenvironment (TME), antigenic heterogeneity, and CAR T-cell exhaustion hinder its effectiveness. This review aims to explore the current landscape of CAR T-cell therapy for CNS tumors, highlighting recent advancements and addressing challenges in achieving therapeutic efficacy. RECENT FINDINGS: Innovative strategies aim to overcome the barriers posed by the TME and antigen diversity, prevent CAR T-cell exhaustion through engineering approaches and combination therapies with immune checkpoint inhibitors to improving treatment outcomes. SUMMARY: Researchers have been actively working to address these challenges. Moreover, addressing the unique challenges associated with neurotoxicity in CNS tumors requires specialized management strategies. These may include the development of grading systems, monitoring devices, alternative cell platforms and incorporation of suicide genes. Continued research efforts and clinical advancements are paramount to overcoming the existing challenges and realizing the full potential of CAR T-cell therapy in treating CNS tumors.

The role of adjuvant chemotherapy in patients with H3K27 altered diffuse midline gliomas: a multicentric retrospective study.

PURPOSE: Adult Diffuse midline glioma (DMG) is a very rare disease. DMGs are currently treated with radiotherapy and chemotherapy even if only a few retrospective studies assessed the impact on overall survival (OS) of these approaches. METHODS: We carried out an Italian multicentric retrospective study of adult patients with H3K27-altered DMG to assess the effective role of systemic therapy in the treatment landscape of this rare tumor type. RESULTS: We evaluated 49 patients from 6 Institutions. The median age was 37.3 years (range 20.1-68.3). Most patients received biopsy as primary approach (n = 30, 61.2%) and radiation therapy after surgery (n = 39, 79.6%). 25 (51.0%) of patients received concurrent chemotherapy and 26 (53.1%) patients received adjuvant temozolomide. In univariate analysis, concurrent chemotherapy did not result in OS improvement while adjuvant temozolomide was associated with longer OS (21.2 vs. 9.0 months, HR 0.14, 0.05-0.41, p < 0.001). Multivariate analysis confirmed the role of adjuvant chemotherapy (HR 0.1, 95%CI: 0.03-0.34, p = 0.003). In patients who progressed after radiation and/or chemotherapy the administration of a second-line systemic treatment had a significantly favorable impact on survival (8.0 vs. 3.2 months, HR 0.2, 95%CI 0.1-0.65, p = 0.004). CONCLUSION: In our series, adjuvant treatment after radiotherapy can be useful in improving OS of patients with H3K27-altered DMG. When feasible another systemic treatment after treatment progression could be proposed.

Central nervous system tumours in neonates: what should the neonatologist know?

Central nervous system (CNS) tumours in neonates are relatively rare and present differently when compared with those occurring later in childhood in terms of aetiology, clinical features, location, histology and prognosis. The clinical presentation is extremely variable. Even if the most frequent clinical sign is a macrocephaly, there are many other non-specific symptoms associated. The prognosis is usually poor with overall survival of less than 30%. Surgery continues to be the primary treatment for neonatal CNS tumours, aiming for a gross total resection, directly correlated with prognosis and the overall outcome. The chemotherapy is the only adjuvant therapy whereas the radiotherapy is avoided under three years of age because of the severe sequelae. Hence the importance of molecular characterization of these neoplasms in order to improve the accuracy of the diagnosis and identify new therapeutic targets. The aim of this review is to describe the main characteristics of these tumours and the recent advances in their treatment in order to recognize these pathologies in the prenatal period and create a multidisciplinary team providing the best possible treatment while minimising the risk of long-term complications. Neonatologists play a key role in the early detection, diagnostic evaluation, management and supportive care of these neonates.  Conclusion: The aim of this review is to describe the main characteristics of these tumours and the recent advances in their treatment in order to ensure the essential knowledge that will help the neonatologist identify them and create a multidisciplinary team providing the best possible treatment while minimising the risk of long-term complications. What is Known: • Neonatal CNS tumours are relatively rare and their early identification is important to identify the best diagnostic-therapeutic management. • Surgery is the main treatment of neonatal CNS tumours. The extent of surgical resection directly correlates with prognosis and outcome. What is New: • Predisposing conditions such as Cancer Predisposition Syndromes must be considered. • Targeted drugs and other therapeutic strategies can be identified through molecular characterization.

Intracerebellar administration of the chemokine Cxcl3 reduces the volume of medulloblastoma lesions at an advanced stage by promoting the migration and differentiation of preneoplastic precursor cells.

The prognosis for many pediatric brain tumors, including cerebellar medulloblastoma (MB), remains dismal but there is promise in new therapies. We have previously generated a mouse model developing spontaneous MB at high frequency, Ptch1+/-/Tis21-/-. In this model, reproducing human tumorigenesis, we identified the decline of the Cxcl3 chemokine in cerebellar granule cell precursors (GCPs) as responsible for a migration defect, which causes GCPs to stay longer in the proliferative area rather than differentiate and migrate internally, making them targets of transforming insults. We demonstrated that 4-week Cxcl3 infusion in cerebella of 1-month-old mice, at the initial stage of MB formation, forces preneoplastic GCPs (pGCPs) to leave lesions and differentiate, with a complete suppression of MB development. In this study, we sought to verify the effect of 4-week Cxcl3 treatment in 3-month-old Ptch1+/-/Tis21-/- mice, when MB lesions are at an advanced, irreversible stage. We found that Cxcl3 treatment reduces tumor volumes by sevenfold and stimulates the migration and differentiation of pGCPs from the lesion to the internal cerebellar layers. We also tested whether the pro-migratory action of Cxcl3 favors metastases formation, by xenografting DAOY human MB cells in the cerebellum of immunosuppressed mice. We showed that DAOY cells express the Cxcl3 receptor, Cxcr2, and that Cxcl3 triggers their migration. However, Cxcl3 did not significantly affect the frequency of metastases or the growth of DAOY-generated MBs. Finally, we mapped the expression of the Cxcr2 receptor in human MBs, by evaluating a well-characterized series of 52 human MBs belonging to different MB molecular subgroups. We found that Cxcr2 was variably expressed in all MB subgroups, suggesting that Cxcl3 could be used for therapy of different MBs.

Machine Learning Analysis in Diffusion Kurtosis Imaging for Discriminating Pediatric Posterior Fossa Tumors: A Repeatability and Accuracy Pilot Study.

Background and purpose: Differentiating pediatric posterior fossa (PF) tumors such as medulloblastoma (MB), ependymoma (EP), and pilocytic astrocytoma (PA) remains relevant, because of important treatment and prognostic implications. Diffusion kurtosis imaging (DKI) has not yet been investigated for discrimination of pediatric PF tumors. Estimating diffusion values from whole-tumor-based (VOI) segmentations may improve diffusion measurement repeatability compared to conventional region-of-interest (ROI) approaches. Our purpose was to compare repeatability between ROI and VOI DKI-derived diffusion measurements and assess DKI accuracy in discriminating among pediatric PF tumors. Materials and methods: We retrospectively analyzed 34 children (M, F, mean age 7.48 years) with PF tumors who underwent preoperative examination on a 3 Tesla magnet, including DKI. For each patient, two neuroradiologists independently segmented the whole solid tumor, the ROI of the area of maximum tumor diameter, and a small 5 mm ROI. The automated analysis pipeline included inter-observer variability, statistical, and machine learning (ML) analyses. We evaluated inter-observer variability with coefficient of variation (COV) and Bland-Altman plots. We estimated DKI metrics accuracy in discriminating among tumor histology with MANOVA analysis. In order to account for class imbalances, we applied SMOTE to balance the dataset. Finally, we performed a Random Forest (RF) machine learning classification analysis based on all DKI metrics from the SMOTE dataset by partitioning 70/30 the training and testing cohort. Results: Tumor histology included medulloblastoma (15), pilocytic astrocytoma (14), and ependymoma (5). VOI-based measurements presented lower variability than ROI-based measurements across all DKI metrics and were used for the analysis. DKI-derived metrics could accurately discriminate between tumor subtypes (Pillai's trace: p < 0.001). SMOTE generated 11 synthetic observations (10 EP and 1 PA), resulting in a balanced dataset with 45 instances (34 original and 11 synthetic). ML analysis yielded an accuracy of 0.928, which correctly predicted all but one lesion in the testing set. Conclusions: VOI-based measurements presented improved repeatability compared to ROI-based measurements across all diffusion metrics. An ML classification algorithm resulted accurate in discriminating PF tumors on a SMOTE-generated dataset. ML techniques based on DKI-derived metrics are useful for the discrimination of pediatric PF tumors.

Evaluating cell culture reliability in pediatric brain tumor primary cells through DNA methylation profiling.

In vitro models of pediatric brain tumors (pBT) are instrumental for better understanding the mechanisms contributing to oncogenesis and testing new therapies; thus, ideally, they should recapitulate the original tumor. We applied DNA methylation (DNAm) and copy number variation (CNV) profiling to characterize 241 pBT samples, including 155 tumors and 86 pBT-derived cell cultures, considering serum vs serum-free conditions, late vs early passages, and dimensionality (2D vs 3D cultures). We performed a t-SNE classification and identified differentially methylated regions in tumors compared to cell models. Early cell cultures recapitulate the original tumor, but serum media and 2D culturing were demonstrated to significantly contribute to the divergence of DNAm profiles from the parental ones. All divergent cells clustered together acquiring a common deregulated epigenetic signature suggesting a shared selective pressure. We identified a set of hypomethylated genes shared among unfaithful cells converging on response to growth factors and migration pathways, such as signaling cascade activation, tissue organization, and cellular migration. In conclusion, DNAm and CNV are informative tools that should be used to assess the recapitulation of pBT-cells from parental tumors.

Malignant peripheral nerve sheath tumor (MPNST) and MPNST-like entities are defined by a specific DNA methylation profile in pediatric and juvenile population.

BACKGROUND: Malignant peripheral nerve sheath tumors (MPNSTs) account for 3-10% of pediatric sarcomas, 50% of which occur in neurofibromatosis type 1 (NF1). Sporadic MPNSTs diagnosis may be challenging due to the absence of specific markers, apart from immunohistochemical H3K27me3 loss. DNA methylation (DNAm) profiling is a useful tool for brain and mesenchymal neoplasms categorization, and MPNSTs exhibit a specific DNAm signature. An MPNST-like group has recently been recognized, including pediatric tumors with retained H3K27me3 mark and clinical/histological features not yet well explored. This study aims to characterize the DNAm profile of pediatric/juvenile MPNSTs/MPNST-like entities and its diagnostic/prognostic relevance. RESULTS: We studied 42 tumors from two groups. Group 1 included 32 tumors histologically diagnosed as atypical neurofibroma (ANF) (N = 5) or MPNST (N = 27); group 2 comprised 10 tumors classified as MPNST-like according to Heidelberg sarcoma classifier. We performed further immunohistochemical and molecular tests to reach an integrated diagnosis. In group 1, DNAm profiling was inconclusive for ANF; while, it confirmed the original diagnosis in 12/27 MPNSTs, all occurring in NF1 patients. Five/27 MPNSTs were classified as MPNST-like: Integrated diagnosis confirmed MPNST identity for 3 cases; while, the immunophenotype supported the change to high-grade undifferentiated spindle cell sarcoma in 2 samples. The remaining 10/27 MPNSTs variably classified as schwannoma, osteosarcoma, BCOR-altered sarcoma, rhabdomyosarcoma (RMS)-MYOD1 mutant, RMS-like, and embryonal RMS or did not match with any defined entity. Molecular analysis and histologic review confirmed the diagnoses of BCOR, RMS-MYOD1 mutant, DICER1-syndrome and ERMS. Group 2 samples included 5 high-grade undifferentiated sarcomas/MPNSTs and 5 low-grade mesenchymal neoplasms. Two high-grade and 4 low-grade lesions harbored tyrosine kinase (TRK) gene fusions. By HDBSCAN clustering analysis of the whole cohort we identified two clusters mainly distinguished by H3K27me3 epigenetic signature. Exploring the copy number variation, high-grade tumors showed frequent chromosomal aberrations and CDKN2A/B loss significantly impacted on survival in the MPNSTs cohort. CONCLUSION: DNAm profiling is a useful tool in diagnostic work-up of MPNSTs. Its application in a retrospective series collected during pre-molecular era contributed to classify morphologic mimics. The methylation group MPNST-like is a 'hybrid' category in pediatrics including high-grade and low-grade tumors mainly characterized by TRK alterations.

Corrigendum: Pediatric CNS tumors and 2021 WHO classification: what do oncologists need from pathologists?

[This corrects the article DOI: 10.3389/fnmol.2024.1268038.].

Pediatric CNS tumors and 2021 WHO classification: what do oncologists need from pathologists?

The fifth edition of the WHO Classification of Tumors of the Central Nervous System (CNS), published in 2021, established new approaches to both CNS tumor nomenclature and grading, emphasizing the importance of integrated diagnoses and layered reports. This edition increased the role of molecular diagnostics in CNS tumor classification while still relying on other established approaches such as histology and immunohistochemistry. Moreover, it introduced new tumor types and subtypes based on novel diagnostic technologies such as DNA methylome profiling. Over the past decade, molecular techniques identified numerous key genetic alterations in CSN tumors, with important implications regarding the understanding of pathogenesis but also for prognosis and the development and application of effective molecularly targeted therapies. This review summarizes the major changes in the 2021 fifth edition classification of pediatric CNS tumors, highlighting for each entity the molecular alterations and other information that are relevant for diagnostic, prognostic, or therapeutic purposes and that patients' and oncologists' need from a pathology report.

Clinicopathological and molecular landscape of 5-year IDH-wild-type glioblastoma survivors: A multicentric retrospective study.

Five-year glioblastoma (GBM) survivors (LTS) are the minority of the isocitrate dehydrogenase (IDH)-wild-type GBM patients, and their molecular fingerprint is still largely unexplored. This multicenter retrospective study analyzed a large LTS-GBM cohort from nine Italian institutions and molecularly characterized a subgroup of patients by mutation, DNA methylation (DNAm) and copy number variation (CNV) profiling, comparing it to standard survival GBM. Mutation scan allowed the identification of pathogenic variants in most cases, showing a similar mutational spectrum in both groups, and highlighted TP53 as the most commonly mutated gene in the LTS group. We confirmed DNAm as a valuable tool for GBM classification with a diagnostic refinement by using brain tumor classifier v12.5. LTS were more heterogeneous with more cases classified as diffuse pediatric high-grade glioma subtypes and having peculiar CNVs. We observed a global higher methylation in CpG islands and in gene promoters of LTS with methylation levels of distinct gene promoters correlating with prognosis.

GD2-Targeting CAR T-cell Therapy for Patients with GD2+ Medulloblastoma.

PURPOSE: Medulloblastoma (MB), the most common childhood malignant brain tumor, has a poor prognosis in about 30% of patients. The current standard of care, which includes surgery, radiation, and chemotherapy, is often responsible for cognitive, neurologic, and endocrine side effects. We investigated whether chimeric antigen receptor (CAR) T cells directed toward the disialoganglioside GD2 can represent a potentially more effective treatment with reduced long-term side effects. EXPERIMENTAL DESIGN: GD2 expression was evaluated on primary tumor biopsies of MB children by flow cytometry. GD2 expression in MB cells was also evaluated in response to an EZH2 inhibitor (tazemetostat). In in vitro and in vivo models, GD2+ MB cells were targeted by a CAR-GD2.CD28.4-1BBζ (CAR.GD2)-T construct, including the suicide gene inducible caspase-9. RESULTS: GD2 was expressed in 82.68% of MB tumors. The SHH and G3-G4 subtypes expressed the highest levels of GD2, whereas the WNT subtype expressed the lowest. In in vitro coculture assays, CAR.GD2 T cells were able to kill GD2+ MB cells. Pretreatment with tazemetostat upregulated GD2 expression, sensitizing GD2dimMB cells to CAR.GD2 T cells cytotoxic activity. In orthotopic mouse models of MB, intravenously injected CAR.GD2 T cells significantly controlled tumor growth, prolonging the overall survival of treated mice. Moreover, the dimerizing drug AP1903 was able to cross the murine blood-brain barrier and to eliminate both blood-circulating and tumor-infiltrating CAR.GD2 T cells. CONCLUSIONS: Our experimental data indicate the potential efficacy of CAR.GD2 T-cell therapy. A phase I/II clinical trial is ongoing in our center (NCT05298995) to evaluate the safety and therapeutic efficacy of CAR.GD2 therapy in high-risk MB patients.

Gliomatosis cerebri in children: A poor prognostic phenotype of diffuse gliomas with a distinct molecular profile.

BACKGROUND: The term Gliomatosis cerebri (GC), a radiology-defined highly infiltrating diffuse glioma, has been abandoned since molecular GC-associated features have not been established yet. METHODS: We conducted a multinational retrospective study of 104 children and adolescents with GC providing comprehensive clinical and (epi-)genetic characterization. RESULTS: Median overall survival (OS) was 15.5 months (interquartile range, 10.9-27.7) with a 2-years survival rate of 28%. Histopathological grading correlated significantly with median OS: CNS WHO grade II: 47.8 months (25.2-55.7); grade III: 15.9 months (11.4-26.3); grade IV: 10.4 months (8.8-14.4). By DNA methylation profiling (n=49), most tumors were classified as pediatric-type diffuse high-grade glioma (pedHGG), H3-/IDH-wildtype (n=31/49, 63.3%) with enriched subclasses pedHGG_RTK2 (n=19), pedHGG_A/B (n=6), and pedHGG_MYCN (n=5), but only one pedHGG_RTK1 case. Within the pedHGG, H3-/IDH-wildtype subgroup, recurrent alterations in EGFR (n=10) and BCOR (n=9) were identified. Additionally, we observed structural aberrations in chromosome 6 in 16/49 tumors (32.7%) across tumor types. In the pedHGG, H3-/IDH-wildtype subgroup TP53 alterations had a significant negative effect on OS. CONCLUSION: Contrary to previous studies, our representative pediatric GC study provides evidence that GC has a strong predilection to arise on the background of specific molecular features (especially pedHGG_RTK2, pedHGG_A/B, EGFR and BCOR mutations, chromosome 6 rearrangements).

Targeted therapy for pediatric central nervous system tumors harboring mutagenic tropomyosin receptor kinases.

The family of the neurotrophic tyrosine kinase receptor (NTRK) gene encodes for members of the tropomyosin receptor kinase (TRK) family. Rearrangements involving NTRK1/2/3 are rare oncogenic factors reported with variable frequencies in an extensive range of cancers in pediatrics and adult populations, although they are more common in the former than in the latter. The alterations in these genes are causative of the constitutive activation of TRKs that drive carcinogenesis. In 2017, first-generation TRK inhibitor (TRKi) larotrectinib was granted accelerated approval from the FDA, having demonstrated histologic-agnostic activity against NTRKs fusions tumors. Since this new era has begun, resistance to first-generation TRKi has been described and has opened the development of second-generation molecules, such as selitrectinib and repotrectinib. In this review, we provide a brief overview of the studies on NTRK alterations found in pediatric central nervous system tumors and first and second-generation TRKi useful in clinical practice.

Case report: A safeguard in the sea of variants of uncertain significance: a case study on child with high risk neuroblastoma and acute myeloid leukemia.

The increased availability of genetic technologies has significantly improved the detection of novel germline variants conferring a predisposition to tumor development in patients with malignant disease. The identification of variants of uncertain significance (VUS) represents a challenge for the clinician, leading to difficulties in decision-making regarding medical management, the surveillance program, and genetic counseling. Moreover, it can generate confusion and anxiety for patients and their family members. Herein, we report a 5-year-old girl carrying a VUS in the Succinate Dehydrogenase Complex Subunit C (SHDC) gene who had been previously treated for high-risk neuroblastoma and subsequently followed by the development of secondary acute myeloid leukemia. In this context, we describe how functional studies can provide additional insight on gene function determining whether the variant interferes with normal protein function or stability.