A comparative analysis of IDH-mutant glioma in pediatric, young adult, and older adult patients

Characteristics and Outcomes of Patients With IDH-Mutant Grade 2 and 3 Gliomas After Deferred or Adjuvant Radiotherapy

BACKGROUND AND OBJECTIVES

Current treatment guidelines for patients with isocitrate dehydrogenase (IDH)-mutant (IDHm) glioma recommend radiation (XRT) and chemotherapy after surgery in most cases based on studies in which XRT was compared with XRT plus chemotherapy. Although XRT has been shown to improve time to tumor progression, there has never been a controlled study in this population in which adjuvant XRT (aXRT) demonstrated superior overall survival (OS) over initial observation. The aim of this study was to evaluate the effect of timing of XRT on survival in IDHm-glioma.

METHODS

We performed a retrospective observational cohort study, comprising a cohort of adult patients with grade 2 or 3 IDHm-gliomas seen at 2 academic centers (University of Washington and Stanford University) between 2007 and 2022 (identified through research data registries). The main comparison of interest was patients who received XRT within 3 months of diagnosis and before progression, that is, as adjuvant treatment (aXRT), versus those who did not have aXRT (deferred XRT, dXRT). The primary outcome measures were median progression-free survival and OS. Survival analysis was performed through multivariable Cox proportional hazard modeling, propensity matching, and subset analysis.

RESULTS

A total of 450 eligible patients were identified (mean age 39.7 years; 41% female). The median survival of the combined cohort was 19.1 years (25th-75th percentiles 9.75-27.8 years). 47.1% of patients received aXRT. Patients with aXRT demonstrated similar time to next intervention (hazard ratio [HR] 0.83, 95% CI 0.65-1.07) but showed a markedly diminished OS compared with the dXRT cohort (HR of death 2.90, 95% CI 1.9-4.42, p < 0.001). This shorter OS with aXRT was appreciated in all assessed subgroups, including patients considered high risk by grade, age, and extent of resection. This shorter OS was also consistent in multivariable analysis and in propensity-matched cohorts.

DISCUSSION

Although retrospective, the marked OS difference between aXRT and dXRT groups suggests that aXRT may be not be as beneficial as what was once thought, especially regarding long-term survival. These results also offer justification for the use of a dXRT group in studies assessing adjuvant treatments, as well as a reconsideration of the current treatment paradigm for these patients, especially given the recent introduction of IDH inhibitors.

Characteristics, outcome, and prognostic factors of young patients with central nervous system World Health Organization grade 3 oligodendrogliomas IDH-mutant and 1p/19q codeleted: A French POLA network study

BACKGROUND

Brain tumors represent one of the main causes of cancer-related mortality in young patients. Among them, oligodendrogliomas (OG) are adult-type diffuse gliomas with the best prognosis. Nevertheless, characterization of these tumors in the young population remains poorly documented. Our objective was to characterize the population of young adults under 40 years of age with grade 3 OG in the POLA cohort.

METHODS

Clinical data prospectively collected for all patients registered with grade 3 OG between April 2009 and August 2021 were extracted from the national POLA database. This study compared the patient subgroup <40 years of age to the one >40 years of age.

RESULTS

The authors included 111 patients <40 years old and 363 patients ≥40 years old. Treatment received did not differ significantly between the two subgroups. Temporal location was more frequent in older patients (p = .009). Patients <40 years old presented more often seizure as initial symptom (p = .003). They had less frequent chromosome 9p loss (p < .001) and less CDKN2A homozygous deletion (p = .024). Median progression-free survival (PFS) was 123 months (range, 86-not reached [NR]) versus 88 months (range, 67-117) (p = .082) and median overall survival (OS) was not reached (range, 147-NR) versus 163 months (range, 137-NR) (p < .001) in younger and older subgroups, respectively. In multivariate analysis, complete or subtotal resection (p = .014) and seizure at diagnosis (p = .032) were associated with better OS.

CONCLUSION

Young patients with grade 3 OG have distinct clinical presentation, molecular features, and outcomes compared to the older patients.

Longitudinal profiling of IDH-mutant astrocytomas reveals acquired RAS-MAPK pathway mutations associated with inferior survival

Background

Isocitrate dehydrogenase (IDH)-mutant astrocytomas represent the most frequent primary intraparenchymal brain tumor in young adults, which typically arise as low-grade neoplasms that often progress and transform to higher grade despite current therapeutic approaches. However, the genetic alterations underlying high-grade transformation and disease progression of IDH-mutant astrocytomas remain inadequately defined.

Methods

Genomic profiling was performed on 205 IDH-mutant astrocytomas from 172 patients from both initial treatment-naive and recurrent post-treatment tumor specimens. Molecular findings were integrated with clinical outcomes and pathologic features to define the associations of novel genetic alterations in the RAS-MAPK signaling pathway.

Results

Likely oncogenic alterations within the RAS-MAPK mitogenic signaling pathway were identified in 13% of IDH-mutant astrocytomas, which involved the KRAS, NRAS, BRAF, NF1, SPRED1, and LZTR1 genes. These included focal amplifications and known activating mutations in oncogenic components (e.g. KRAS, BRAF), as well as deletions and truncating mutations in negative regulatory components (e.g. NF1, SPRED1). These RAS-MAPK pathway alterations were enriched in recurrent tumors and occurred nearly always in high-grade tumors, often co-occurring with CDKN2A homozygous deletion. Patients whose IDH-mutant astrocytomas harbored these oncogenic RAS-MAPK pathway alterations had inferior survival compared to those with RAS-MAPK wild-type tumors.

Conclusions

These findings highlight novel genetic perturbations in the RAS-MAPK pathway as a likely mechanism contributing to the high-grade transformation and treatment resistance of IDH-mutant astrocytomas that may be a potential therapeutic target for affected patients and used for future risk stratification.

The Clinical and Molecular Landscape of Rosette-Forming Glioneuronal Tumors

BACKGROUND

Rosette-Forming Glioneuronal Tumors (RGNTs) are rare, typically benign central nervous system tumors primarily located in the fourth ventricle and pineal region. Despite being classified as WHO grade I with generally favorable prognoses, RGNTs present complexities in their molecular mechanisms, occasional malignant transformation, and epidemiological characteristics that require further investigation.

METHOD

This study systematically reviews the existing literature to analyze the epidemiological patterns, MRI characteristics, pathological features, diagnostic challenges, and molecular mechanisms associated with RGNTs, aiming to provide a comprehensive theoretical foundation for clinical practice and future research.

RESULTS

Through an in-depth review of recent studies, key molecular mechanisms, including mutations in FGFR1, PIK3CA, TERT, and IDH1/2, are highlighted. Additionally, the challenges in accurate diagnosis and the potential for misdiagnosis are discussed, emphasizing the importance of thorough molecular analysis in clinical settings. The literature indicates that RGNTs predominantly affect young adults and adolescents, with a slight female predominance. MRI typically reveals mixed cystic-solid lesions, often accompanied by hydrocephalus. Pathologically, RGNTs are characterized by a combination of neuronal and glial components, with immunohistochemical staining showing positivity for Synaptophysin and GFAP. High frequencies of FGFR1 and PIK3CA mutations underscore the significance of these pathways in RGNT pathogenesis and progression. Although RGNTs generally exhibit low malignancy, the TERT mutations identified in some cases suggest a risk of malignant transformation.

CONCLUSIONS

This study concludes that while current treatment strategies focus on surgical resection, integrating molecular diagnostics and targeted therapies may be essential for managing recurrent or refractory RGNTs. Future research should explore the impact of various gene mutations on tumor behavior and their correlation with clinical outcomes, to optimize individualized therapeutic strategies and improve patient survival and quality of life.