NF2 mutations are associated with resistance to radiation therapy for grade 2 and grade 3 recurrent meningiomas

A four-hit mechanism is sufficient for meningioma development

PURPOSE

Meningiomas are central nervous system tumors whose incidence increases with age. Benign meningioma pathogenesis involves germline or somatic mutation of target genes, such as NF2, leading to clonal expansion. We used an established cancer epidemiology model to investigate the number of rate-limiting steps sufficient for benign meningioma development.

METHODS

Incidence data was obtained from the Surveillance, Epidemiology and End Results Program (SEER) for nonmalignant meningioma from 2004 to 2020. Age-adjusted incidence rates per 100,000 person-years were divided into 5-year bands. This was repeated for vestibular schwannomas as a negative control. The Armitage-Doll methodology was applied. Mathematical solutions correcting for volatile tumor microenvironments were applied to fit higher-order models using polynomial regression when appropriate. A 75:25 training:test split was utilized for validation.

RESULTS

222,509 cases of benign meningiomas were identified. We noted strong linear relationships between log-transformed incidence and age across the cohort and multiple subpopulations: male, white, black, Hispanic, Asian/Pacific Islander, and American Indian subpopulations all demonstrated R2 = 0.99. Slopes were between 3.1 and 3.4, suggesting a four-step process for benign meningioma development. Female patients exhibited nonlinear deviations, but the corrected model demonstrated R2 = 0.99 with a four-hit pathway. This model performed robustly on test data with R2 = 0.99. Vestibular schwannomas demonstrated a slope of 2.1 with R2 = 0.99, suggesting a separate three-step process.

CONCLUSION

Four mutations are uniquely required for the development of benign meningiomas. Correcting for volatile tumor microenvironments reliably accounted for nonlinear deviations in behavior. Further studies are warranted to elucidate genomic findings suggestive of key mutations in this pathway.

NF2 mutation associated with accelerated time to recurrence for older patients with atypical meningiomas

PURPOSE

Meningiomas occur more frequently in older adults, with the incidence rates increasing from 5.8/100,000 for adults 35-44 years old to 55.2/100,000 for those 85+. Due to the increased risk of surgical management in older adults, there is a need to characterize the risk factors for aggressive disease course to inform management decisions in this population. We therefore sought to determine age-stratified relationships between tumour genomics and recurrence after resection of atypical meningiomas.

METHODS

We identified 137 primary and recurrent Grade 2 meningiomas from our existing meningioma genomic sequencing database. We examined the differential distribution of genomic alterations in those older than 65 compared to younger. We then performed an age stratified survival analysis to model recurrence for a mutation identified as differentially present.

RESULTS

In our cohort of 137 patients with grade 2 meningiomas, alterations in NF2 were present at a higher rate in older adults compared to younger (37.8% in < 65 vs. 55.3% in > 65; recurrence adjusted p-value =0.04). There was no association between the presence of NF2 and recurrence in the whole cohort. In the age-stratified model for those less than 65 years old, there was again no relationship. For patients in the older age stratum, there is a relationship between NF2 and worsened recurrence outcomes (HR = 3.64 (1.125 - 11.811); p = 0.031).

CONCLUSIONS

We found that mutations in NF2 were more common in older adults. Further, the presence of mutant NF2 was associated with an increased risk of recurrence in older adults.

Association between tumor mutations and meningioma recurrence in Grade I/II disease

BACKGROUND

Meningiomas are common intracranial tumors with variable prognoses not entirely captured by commonly used classification schemes. We sought to determine the relationship between meningioma mutations and oncologic outcomes using a targeted next-generation sequencing panel.

MATERIALS AND METHODS

We identified 184 grade I and II meningiomas with both >90 days of post-surgical follow-up and linked targeted next-generation sequencing. For mutated genes in greater than 5% of the sample, we computed progression-free survival Cox-regression models stratified by gene. We then built a multi-gene model by including all gene predictors with a p-value of less than 0.20. Starting with that model, we performed backward selection to identify the most predictive factors.

RESULTS

ATM (HR = 4.448; 95% CI: 1.517-13.046), CREBBP (HR = 2.727; 95% CI = 1.163-6.396), and POLE (HR = 0.544; HR = 0.311-0.952) were significantly associated with alterations in disease progression after adjusting for clinical and pathologic factors. In the multi-gene model, only POLE remained a significant predictor of recurrence after adjusting for the same clinical covariates. Backwards selection identified recurrence status, resection extent, and mutations in ATM (HR = 7.333; 95% CI = 2.318-23.195) and POLE (HR = 0.413; 95% CI = 0.229-0.743) as predictive of recurrence.

CONCLUSIONS

Mutations in ATM and CREBBP were associated with accelerated meningioma recurrence, and mutations in POLE were protective of recurrence. Each mutation has potential implications for treatment. The effect of these mutations on oncologic outcomes and as potential targets for intervention warrants future study.