a-whole-body-dosimetry-protocol-for-peptide-receptor-radionuclide

A Whole Body Dosimetry Protocol for Peptide-Receptor Radionuclide Therapy (PRRT): 2D Planar Image and Hybrid 2D+3D SPECT/CT Image Methods

Peptide-receptor-radionuclide-therapy (PPRT) is a targeted therapy that combines a short-range energy radionuclide with a substrate with high specificity ...

Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy

Peptide receptor radionuclide therapy (PRRT) is a valid therapy for grade 1/2 gastroenteropancreatic (GEP) neuroendocrine neoplasms (NENs). Although a median progression-free survival (PFS) of more than 20 months is frequently observed, the majority of patients relapse after 2 - 3 years. In the present study, we investigated the use of low dosage re-treatment with (177)Lu-DOTATATE (Lu-PRRT) in patients with GEP-NENs who relapsed after treatment with (90)Y-DOTATOC (Y-PRRT).

Feasibility and utility of re-treatment with (177)Lu-DOTATATE in GEP-NENs relapsed after treatment with (90)Y-DOTATOC.

Radio-ligand therapy (RLT) withLu-PSMA-617 is a promising option for patients with metastatic castration-resistant prostate-cancer (mCRPC). A prospective phase-II study (EUDRACT/RSO,2016-002732-32) on mCRPC is ongoing at IRST (Meldola, Italy). A total of 9 patients (median age: 68 y, range: 53⁻85) were enrolled for dosimetry evaluation of parotid glands (PGs), kidneys, red marrow (RM) and whole body (WB). Folic polyglutamate tablets were orally administered as PGs protectors and 500 mL of a 10% mannitol solution was intravenously infused to reduce kidney uptake. The whole body planar image (WBI) and blood samples were acquired at different times post infusion (1 h, 16⁻24 h, 36⁻48 h and 120 h). Dose calculation was performed with MIRD formalism (OLINDA/EXM software). The median effective half-life was 33.0 h (range: 25.6⁻60.7) for PGs, 31.4 h (12.2⁻80.6) for kidneys, 8.2 h (2.5⁻14.7) for RM and 40.1 h (31.6⁻79.7) for WB. The median doses were 0.48 mGy/MBq (range: 0.33⁻2.63) for PGs, 0.70 mGy/MBq (0.26⁻1.07) for kidneys, 0.044 mGy/MBq (0.023⁻0.067) for RM and 0.04 mGy/MBq (0.02⁻0.11) for WB. A comparison with previously published dosimetric data was performed and a significant difference was found for PGs while no significant difference was observed for the kidneys. For PGs, the possibility of reducing uptake by administering glutamate tablets during RLT seems feasible while further research is warranted for a more focused evaluation of the reduction in kidney uptake.

Stefano Severi

Nuclear Medicine Unit

Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy

A Whole Body Dosimetry Protocol for Peptide-Receptor Radionuclide Therapy (PRRT): 2D Planar Image and Hybrid 2D+3D SPECT/CT Image Methods