Nicola Cosgrove ¹ Orla M Fitzpatrick ² Liam Grogan ² Bryan T Hennessy ² Simon J Furney ^1* Sinead Toomey ^1*

• ¹ Royal College of Surgeons in Ireland, Dublin, County Dublin, Ireland
• ² Beaumont Hospital, Dublin, Ireland

Metastatic meningioma is rare occurring in less than 1% of patients and very few case studies have been reported, in particular for those that have spread to the lung. Here we describe a rare case of metastatic meningioma to the lung. Following discussion at a medical oncology multi-disciplinary team meeting, whole genome sequencing was requested in November 2021 and discussed at a neurosurgical molecular tumour board in June 2022. Sequencing was performed on matched longitudinal collected samples of the primary tumour resection; the re-excised recurrent tumour after adjuvant radiation therapy; the lung metastases before treatment with Sunitinib and one paired blood sample for tumour-normal analysis.Whole genome characterisation and clonal evolution analysis confirmed NF2 gene loss as the main driver of this cancer. In the same cancer clone as NF2, we identified a BRCA2 (p.E51K) mutation present in all tumours, which may represent a potential driver event, though evidence supporting this is currently limited.Although this mutation is predicted to potentially influence homologous recombination, its clinical relevance as a biomarker for PARP inhibition remains speculative and requires further investigation. We also noted a SETD2 (p.S1885N) mutation that was present only in the recurrence which was identified as a predicted biomarker of response to WEE1 inhibition. There was a stepwise increase in tumour mutational burden (TMB) from the primary meningioma to lung metastases, suggesting this patient may have been a candidate for immunotherapy.