[177Lu]Lu-PSMA Therapy as an Individual Treatment Approach for Patients with High-Grade Glioma: Dosimetry Results and Critical Statement

Abstract

The theranostic use of prostate-specific membrane antigen (PSMA) appears to be promising in patients with high-grade glioma. This study investigated [177Lu]Lu-PSMA therapy as an individual treatment approach with a focus on intratherapeutic dosimetry. Methods: Three patients were treated with a median of 6.03 GBq (interquartile range [IQR], 5.74–6.10) of [177Lu]Lu-PSMA. Intratherapeutic dosimetry was performed using a hybrid scenario with planar whole-body scintigraphy at 2, 24, and 48 h after treatment injection and SPECT/CT at 48 h after injection. Additive whole-body scintigraphy at 8 d after injection was performed on 1 patient. Results: The median doses were 0.56 Gy (IQR, 0.36–1.25 Gy) to tumor, 0.27 Gy (IQR, 0.16–0.57 Gy) to risk organs, 2.13 Gy (IQR, 1.55–2.89 Gy) to kidneys, and 0.76 Gy (IQR, 0.70–1.20 Gy) to salivary glands. Whole-body exposure was 0.11 Gy (IQR, 0.06–0.18 Gy). Conclusion: Because the intratherapeutic tumor dose is lower than that used in external radiation oncology, the effectiveness of treatment is questionable.