E4999. Theranostics in Meningiomas: The Evolving Role of Somatostatin Receptor Imaging in Recurrent Meningioma
  1. Johnny Yang; University of Mississippi Medical Center
  2. Logan Ryals; University of Mississippi Medical Center
  3. Bryson Brister; University of Mississippi Medical Center
  4. Clayton Rowell; University of Mississippi Medical Center
  5. Vani Vijayakumar; University of Mississippi Medical Center
Meningiomas are the most common primary intracranial tumor worldwide. More commonly presenting in elderly patients, these tumors are more likely to be malignant and recurrent in patients with an NF-2 gene mutation than patients lacking NF-2 mutation. While meningiomas are usually treated with surgical intervention, adjuvant radiation may be employed in cases of subtotal resection and/or high histopathologic grade of the tumor. Contrast-enhanced MRI is the gold standard for postoperative assessment and adjuvant treatment planning. However, MRI may have limited accuracy, particularly in the presence of posttreatment changes to surrounding structures. Somatostatin receptor imaging (SSRI) with the Octreoscan or, more recently, with 68Ga-DOTATATE has shown promise in the evaluation of meningiomas postoperatively. Gallium-68-DOTATATE is a PET radiotracer that targets somatostatin receptor 2A (SSTR2A). SSTR2A is a reliable biomarker that is found in meningiomas. Gallium-68-DOTATATE PET/MRI is an additional tool that may be used in the assessment of both treatment naïve meningiomas and meningiomas that have been resected and/or irradiated. This modality allows for improved diagnosis and evaluation of residual disease.

Educational Goals / Teaching Points
Highlight somatostatin receptor imaging avidity in detecting meningiomas. Discuss the role of Octreoscan and 68Ga-DOTA imaging in the diagnosis and management of recurrent meningioma. – Discuss the use of theranostics with 177Lu-DOTA peptide receptor radioligand therapy (PRRT).

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
To date, there exists no standard treatment for progressive meningiomas beyond surgery and radiation. Outcomes in patients with tumors refractory to surgery and stereotactic radiosurgery are poor. In a meta-analysis of 47 studies, these patients were found to have 6-month progression free survival (PFS) of 26–29%, including patients with WHO-I meningiomas. Efforts to improve PFS in meningiomas refractory to surgery and radiation have focused on chemotherapy, immunotherapy, and antiangiogenic agents, but have had limited success.

An important implication of 68Ga-DOTATATE-PET/MRI in meningioma is the emergence of SSTR2-targeted radionuclide therapy PRRT with the use of 177Lu-DOTA. In a pilot cohort of 20 patients, there was significant improvement in PFS compared to historic controls. This finding underlies the potential importance of SSRI and somatostatin-targeted theranostic therapy for the treatment of progressive meningioma.