PATH-52. MENINGIOMA MOLECULAR GROUPS PREDICT RESPONSE TO SURGERY AND RADIOTHERAPY

Abstract INTRODUCTION Aside from surgery, radiotherapy (RT) remains the only accepted treatment for meningiomas. However, patient selection for adjuvant RT remains controversial. We aimed to evaluate whether novel molecular and methylation groups could more accurately predict outcomes following surgery and adjuvant RT compared to WHO grade using a large clinical-molecular dataset. Method: We utilized publicly available, clinically annotated molecular datasets of meningiomas and generated de novo DNA-methylation and RNA-sequencing data. Meningiomas were classified into different molecular and methylation groups based on the methodologies of their original publications (Nassiri et al. [2021], Bayley et al.[2022], Choudhury et al.[2022], Sahm et al.[2017]) and progression-free survival (PFS) following surgery with and without adjuvant RT were analyzed. RESULTS A total of 2029 meningiomas from 11 different institutions with adjuvant RT data were included. Adjuvant RT was associated with improved PFS in WHO grade 1 meningiomas following subtotal resection(STR) and WHO grade 2 meningiomas following gross total resection(GTR) or STR. Multivariable analysis using Cox proportional hazards regression models showed that having a meningioma belonging to a hypermetabolic (MG3)(HR 3.63, 95%CI 1.47-8.99), or proliferative (MG4)(HR 7.24, 95%CI 2.84-18.49) molecular group were associated with worse PFS following surgery and adjuvant RT when controlling for age, gender, WHO grade, and extent of resection. Meningiomas belonging to DKFZ MC-intermediate, MC-malignant and UCSF hypermitotic methylation groups were also associated with worse outcomes. These relationships held true even in subgroup analysis with only WHO grade 2 meningiomas and following propensity score matching for the same clinical covariates above. Nearly all molecular and methylation classifications predicted 5-year PFS including following surgery and adjuvant RT (area under the curve [AUC] 0.61-0.72) better than WHO grade (AUC 0.51). CONCLUSIONS Molecular classification improves clinical outcome prediction for meningiomas following surgery and adjuvant radiotherapy, supporting the rationale for molecularly informed treatment decisions and potential clinical trial stratification.