Implications of Concurrent IDH1 and IDH2 Mutations on Survival in Glioma-A Case Report and Systematic Review

Impact of IDH mutation and adjuvant chemo(radio)therapy on survival outcome in grade II/III astrocytoma: a retrospective cohort study based on SEER database

Background

Astrocytoma is a primary brain tumor arising from specific glial cells called astrocytes. Isocitrate dehydrogenase (IDH) mutations represent an early oncogenic event in glioma evolution. The 2-hydroxyglutarate builds up and is produced in grade II/III astrocytoma. Adjuvant chemo(radio)therapy is the standard treatment. Optimal treatment strategies are controversial due to the risk-benefit ratio. This study aimed to assess the effect of IDH mutation on the survival outcome with different treatment modalities for better understanding of the disease.

Methods

Data were obtained from the SEER program for patients with diffuse and anaplastic astrocytoma diagnosed from 2018 to 2020. Patients were divided into wild-type (wIDH) and mutant-type (mIDH) groups and subclassified based on the received adjuvant therapy (chemotherapy, radiotherapy, chemoradiotherapy). All patients had surgery (tumor destruction, local excision, partial, radial, and total gross resection). SPSS 27 was used for statistical analysis, Kaplan-Meier curve, and Long-Rank test for survival analysis.

Results

Out of 811 patients, 486 (59.9%) had mIDH, and 325 (40.1%) had wIDH. The 2-year relative survival for mIDH was 95% and 51% for wIDH, P < 0.001. The highest 2-year relative survival among the mIDH group was for patients who received adjuvant chemotherapy (100%), compared to adjuvant chemoradiotherapy (95.3%) and adjuvant radiotherapy (81.2%), P = 0.051. The 2-year survival for wIDH who received adjuvant chemotherapy, combined adjuvant chemoradiotherapy, and adjuvant radiotherapy were 66%, 51%, and 42%, respectively; P = 0.022.

Conclusions

The mIDH had better 2-year relative survival compared to wIDH across all treatment modalities. Adjuvant chemotherapy had more than 20% survival benefit compared to radiotherapy in mIDH and wIDH. These results highlight adjuvant chemotherapy as the modality of choice for mIDH to improve the survival outcome and avoid radiotherapy's unfavorable side effects. The study was registered at Clinicaltrial.gov with identification number of NCT06620926.

Development and Validation of a Prognostic Molecular Phenotype and Clinical Characterization in Grade III Diffuse Gliomas Treatment with Radio-Chemotherapy

Background

The relationship between molecular phenotype and prognosis in high-grade gliomas (WHO III and IV, HGG) treated with radiotherapy and chemotherapy is not fully understood and needs further exploration.

Methods

The HGG patients following surgery and treatment with radiotherapy and chemotherapy. Univariate and multivariate Cox analyses were used to assess the independent prognostic factors. The nomogram model was established, and its accuracy was determined via the calibration plots.

Results

A total of 215 and 88 patients had grade III glioma and grade IV glioma, respectively. Grade III oligodendroglioma (OG-G3) patients had the longest mPFS and mOS than other grade III pathology, while grade III astrocytoma (AA-G3) patients were close to IDH-1 wildtype glioblastoma (GBM) and had a poor prognosis. The IDH-1 mutant group had a better mPFS and mOS than the IDH-1 wildtype group in all grade III patients, OG-G3 and AA-G3 patients. Furthermore, 1p/19q co-deletion group had a longer mPFS and mOS than 1p/19q non-deletion group in all grade III patients. IDH-1 mutation and 1p/19q co-deletion patients had the best prognosis than other molecular types. Also, the MGMT methylation and IDH-1 mutation or 1p/19q co-deletion group had a longer mPFS and mOS than the MGMT unmethylation and IDH-1 wildtype or 1p/19q non-codeletion of grade III patients. In addition, the low Ki-67 expression group had a better prognosis than high Ki-67 expression group in grade III patients. Univariate and multivariate COX showed that 1p/19q co-deletion and MGMT methylation were the independent prognostic factors for mPFS and mOS. The calibration curve showed that the established nomogram could well predict the survival based on these covariates.

Conclusion

The AA-G3 with IDH-1 wildtype, MGMT unmethylation or 1p/19q non-codeletion patients was resistant to radiotherapy and chemotherapy, has a poor prognosis and needs a more active treatment.

Genomic, epigenomic and transcriptomic landscape of glioblastoma

The mostly aggressive and extremely malignant type of central nervous system is Glioblastoma (GBM), which is characterized by an extremely short average survival time of lesser than 16 months. The primary cause of this phenomenon can be attributed to the extensively altered genome of GBM, which is characterized by the dysregulation of numerous critical signaling pathways and epigenetics regulations associated with proliferation, cellular growth, survival, and apoptosis. In light of this, different genetic alterations in critical signaling pathways and various epigenetics regulation mechanisms are associated with GBM and identified as distinguishing markers. Such GBM prognostic alterations are identified in PI3K/AKT, p53, RTK, RAS, RB, STAT3 and ZIP4 signaling pathways, metabolic pathway (IDH1/2), as well as alterations in epigenetic regulation genes (MGMT, CDKN2A-p16INK4aCDKN2B-p15INK4b). The exploration of innovative diagnostic and therapeutic approaches that specifically target these pathways is utmost importance to enhance the future medication for GBM. This study provides a comprehensive overview of dysregulated epigenetic mechanisms and signaling pathways due to mutations, methylation, and copy number alterations of in critical genes in GBM with prevalence and emphasizing their significance.

CDKN2A/B Homozygous Deletions in Astrocytomas: A Literature Review

Genomic alterations of CDKN2A and CDKN2B in astrocytomas have been an evolving area of study for decades. Most recently, there has been considerable interest in the effect of CDKN2A and/or CDKN2B (CDKN2A/B) homozygous deletions (HD) on the prognosis of isocitrate dehydrogenase (IDH)-mutant astrocytomas. This is highlighted by the adoption of CDKN2A/B HD as an essential criterion for astrocytoma and IDH-mutant central nervous system (CNS) WHO grade 4 in the fifth edition of the World Health Organisation (WHO) Classification of Central Nervous System Tumours (2021). The CDKN2A and CDKN2B genes are located on the short arm of chromosome 9. CDKN2A encodes for two proteins, p14 and p16, and CDKN2B encodes for p15. These proteins regulate cell growth and angiogenesis. Interpreting the impact of CDKN2A/B alterations on astrocytoma prognosis is complicated by recent changes in tumour classification and a lack of uniform standards for testing CDKN2A/B. While the prognostic impact of CDKN2A/B HD is established, the role of different CDKN2A/B alterations-heterozygous deletions (HeD), point mutations, and promoter methylation-is less clear. Consequently, how these alternations should be incorporated into patient management remains controversial. To this end, we reviewed the literature on different CDKN2A/B alterations in IDH-mutant astrocytomas and their impact on diagnosis and management. We also provided a historical review of the changing impact of CDKN2A/B alterations as glioma classification has evolved over time. Through this historical context, we demonstrate that CDKN2A/B HD is an important negative prognostic marker in IDH-mutant astrocytomas; however, the historical data is challenging to interpret given changes in tumour classification over time, variation in the quality of evidence, and variations in the techniques used to identify CDKN2A/B deletions. Therefore, future prospective studies using uniform classification and detection techniques are required to improve the clinical interpretation of this molecular marker.

RYK Gene Expression Associated with Drug Response Variation of Temozolomide and Clinical Outcomes in Glioma Patients

Temozolomide (TMZ) chemotherapy is an important tool in the treatment of glioma brain tumors. However, variable patient response and chemo-resistance remain exceptionally challenging. Our previous genome-wide association study (GWAS) identified a suggestively significant association of SNP rs4470517 in the RYK (receptor-like kinase) gene with TMZ drug response. Functional validation of RYK using lymphocytes and glioma cell lines resulted in gene expression analysis indicating differences in expression status between genotypes of the cell lines and TMZ dose response. We conducted univariate and multivariate Cox regression analyses using publicly available TCGA and GEO datasets to investigate the impact of RYK gene expression status on glioma patient overall (OS) and progression-free survival (PFS). Our results indicated that in IDH mutant gliomas, RYK expression and tumor grade were significant predictors of survival. In IDH wildtype glioblastomas (GBM), MGMT status was the only significant predictor. Despite this result, we revealed a potential benefit of RYK expression in IDH wildtype GBM patients. We found that a combination of RYK expression and MGMT status could serve as an additional biomarker for improved survival. Overall, our findings suggest that RYK expression may serve as an important prognostic or predictor of TMZ response and survival for glioma patients.

Concurrent IDH1 and IDH2 mutations in glioblastoma: A case report

Isocitrate dehydrogenase (IDH) mutations are cornerstone diagnostic features in glioma classification. IDH mutations are typically characterized by mutually exclusive amino acid substitutions in the genes encoding for the IDH1 and the IDH2 enzyme isoforms. We report our institutional case of a diffuse astrocytoma with progression to secondary glioblastoma and concurrent IDH1/IDH2 mutations. A 49-year-old male underwent a subtotal resection of a lobular lesion within the right insula in 2013, revealing a WHO grade 3 anaplastic oligoastrocytoma, IDH1 mutated, 1p19q intact. Symptomatic tumor progression was suspected in 2018, leading to a surgical tumor biopsy that demonstrated WHO grade 4 IDH1 and IDH2 mutant diffuse astrocytoma. The patient subsequently underwent surgical resection followed by medical management and finally died in 2021. Although concurrent IDH1/IDH2 mutations have been rarely reported in the current literature, further study is required to better define their impact on patients’ prognoses and their response to targeted therapies.