MRC1 and meningioma: A prior study of meningioma sequencing data found high mutation burden, defined as at least 10 mutations per megabase,13 in approximately 2.5% of meningiomas, with a small subgroup of meningiomas showing loss of function mutations in MMR pathway members.14 There are currently several ongoing clinical trials studying ICI in meningiomas alone (NCT03173950, NCT03279692, NCT03016091) or in combination with radiotherapy (NCT03604978, NCT02648997, NCT04659811, NCT03267836), all with inclusion criteria that are agnostic to MMR status.