Abstract
Radio-ligand therapy (RLT) with177Lu-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.
Highlights
The most frequent cancer in adult males is prostate cancer (PCa)
Dosimetry evaluation was performed on 9 patients (6 during the first cycle and 3 during the second)
Three acquisitions were only performed for patient no. 7, while red marrow dosimetry was performed in
Summary
Prognosis is dependent on the tumor stage and is poor in patients with metastatic disease (mPC) as it has a five-year survival of only 29% [1]. Limited treatment options are available for the subgroup of metastatic patients with castration-resistant disease (mCRPC). The currently available treatment options are taxane-based chemotherapies (e.g., docetaxel, cabazitaxel) and novel second-line hormone therapies (e.g., enzalutamide, abiterone), which are all associated with moderate survival and poor quality of life [2,3]. Radioligand therapy (RLT), which is based on a combination of a short-range energy radionuclide and a substrate with high specificity for cancer cell receptors, enables lesions to be treated with targeted radiation. Prostate-specific membrane antigen (PSMA) is a protein overexpressed in 90–100% of local PCa lesions and metastatic disease (lymph node and bone). Different RLT radiopharmaceuticals exploiting PSMA-targeting radioligands have been developed, among which the novel theragnostic
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