Peptide Receptor Radionuclide Therapy in Advanced Refractory Meningiomas: Efficacy and Toxicity in a Long Follow-up

Recurrence of meningiomas after surgery and radiotherapy deserves specific attention because of the lack of active third-line therapies. Somatostatin receptors are usually overexpressed on the cell membrane of meningiomas, and this has led the way to a radionuclide theranostic approach. Diagnoses with ⁶⁸Ga-DOTA-octreotide and peptide receptor radionuclide therapy (PRRT) with ⁹⁰Y/¹⁷⁷Lu-DOTA-octreotide are currently possible options within experimental protocols or as compassionate use in small patient groups. Methods: From October 2009 to October 2021, 42 meningioma patients with radiologic recurrence after standard therapies were treated with ⁹⁰Y-DOTATOC (dosage of 1.1 or 5.5 GBq) or with ¹⁷⁷Lu-DOTATATE (dosage of 3.7 or 5.5 GBq) in a mean of 4 cycles. All patients showed intense uptake at diagnostic ⁶⁸Ga-DOTATOC PET/CT or in an ¹¹¹In-octreotide scan. Results: Of 42 patients treated, 5 patients received ⁹⁰Y-DOTATOC with a cumulative activity of 11.1 GBq and 37 patients received ¹⁷⁷Lu-DOTATATE with a cumulative activity of 22 GBq. The disease control rate was 57%. With a median follow-up of 63 mo, median progression-free survival was 16 mo, and median overall survival was 36 mo. Retreatment ¹⁷⁷Lu-PRRT was performed in 6 patients with an administered median activity of 13 GBq in a mean of 5 cycles. With a 75.8-mo follow-up, median progression-free survival and overall survival were 6.5 and 17 mo, respectively. Only 1 patient discontinued the treatment because of grade 3 platelet toxicity. A rapidly transient grade 2 neutropenia was recorded in 1 retreated patient. Conclusion: PRRT in patients with advanced meningiomas overexpressing somatostatin receptor 2 was active and well tolerated, showing a 57% disease control rate. Furthermore, PRRT could represent a potential retreatment option. Further studies, also in combination with other treatments, are warranted.