Comparing the Radiopharmaceutical Drug, [177Lu]Lu-DOTATATE, to Standard of Care Treatment for Patients With Meningioma That Has Come Back After Prior Treatment

Inclusion Criteria: STEP 1 REGISTRATION * Aged \>= 18 years * Histologically confirmed diagnosis of WHO grade 1-3 meningioma * Presence of measurable contrast-enhancing disease on gadolinium-enhanced MRI brain scan defined as at least one lesion with two perpendicular diameters measuring ≥10 mm on two or more axial slices (≤ 5 mm interslice thickness, ≤ 1 mm interslice gap) per current RANO meningioma criteria * Progression of disease determined by local radiology review per current RANO meningioma criteria, defined as * ≥ 15% increase in sum of product of perpendicular measurements of up to 5 measurable target lesions within the last 6 months, or * ≥ 25% increase in sum of product of perpendicular measurements of up to 5 measurable target lesions within the last 12 months, or * Development of a new measurable lesion * The following scans must be available for submission for central radiology review: * Pre-progression gadolinium-enhanced MRI brain scan * Progression gadolinium-enhanced MRI brain scan STEP 2 REGISTRATION * Progression of disease determined by central radiology review per current RANO meningioma criteria, defined as * ≥ 15% increase in sum of product of perpendicular measurements of up to 5 measurable target lesions within the last 6 months, or * ≥ 25% increase in sum of product of perpendicular measurements of up to 5 measurable target lesions within the last 12 months, or * Development of a new measurable lesion. * \[68Ga\]Ga-DOTATATE u…