[177Lu]Lu-DOTATATE for refractory meningiomas: factors associated with the therapeutic response and initial tumor dosimetric data.

PURPOSE: This study aimed to reveal the factors affecting the therapeutic response of refractory meningiomas treated with [177Lu]Lu-DOTATATE and to collect initial tumor absorbed doses.

METHODS

Patients with refractory and progressive meningiomas treated with [177Lu]Lu-DOTATATE from 2021 to 2024 were retrospectively included. Association analyses of clinical factors, WHO grade, prior therapy (surgery, radiation, systemic therapy: bevacizumab or a combination of octreotide/everolimus), 3D-MRI volume and pretreatment PET parameters with 6-month progression-free survival (PFS-6), as defined by the 3D-RANO criteria, were performed. Growth rates obtained via MRI and tumor absorbed doses (TAD) were also calculated.

RESULTS

Sixteen patients (60 [55;68] years old) underwent 4 [2;4] cycles of [177Lu]Lu-DOTATATE, with a TAD/cycle of 0.45 [0.30;0.83] Gy/GBq/cycle. Only prior systemic therapy was found as a risk factor for PFS-6 (p ≤ 0.05), with an impact on tumor growth rate (TGR) (4 vs. 12 patients, + 125% vs. -107%, p < 0.01). For the 12 patients without any prior systemic therapy, the PFS-6 was 67% (8/12 patients) whereas it was 0% in the other group, those with prior systemic therapy. No associations between the TAD and difference in the TGR before/after SSTR-RT were observed in the overall population (p = 0.10) or in the population of patients without any prior therapy (p = 0.72).

CONCLUSION

[177Lu]Lu-DOTATATE appears effective in refractory meningiomas with no prior systemic therapy, even if the TADs are relatively low. [177Lu]Lu-DOTATATE should be proposed as early as possible in the treatment course of refractory meningiomas.