Author/Authors :
Kabasakal, Levent İstanbul University Cerrahpaşa Faculty of Medicine - Department of Nuclear Medicine - İstanbul, Turkey , Yeyin, Nami İstanbul University Cerrahpaşa Faculty of Medicine - Department of Nuclear Medicine - İstanbul, Turkey , Abuqbeitah, Mohammad İstanbul University Cerrahpaşa Faculty of Medicine - Department of Nuclear Medicine - İstanbul, Turkey , Aygün, Aslan İstanbul University Cerrahpaşa Faculty of Medicine - Department of Nuclear Medicine - İstanbul, Turkey , Karayel, Emre İstanbul University Cerrahpaşa Faculty of Medicine - Department of Nuclear Medicine - İstanbul, Turkey , Pehlivanoğlu, Hüseyin İstanbul University Cerrahpaşa Faculty of Medicine - Department of Nuclear Medicine - İstanbul, Turkey , Toklu, Türkay Yeditepe University Faculty of Medicine - Department of Nuclear Medicine - İstanbul, Turkey , Selçuk, Nalan Alan Yeditepe University Faculty of Medicine - Department of Nuclear Medicine - İstanbul, Turkey , Demirci, Emre Şişli Etfal Training and Research Hospital - Clinic of Nuclear Medicine - İstanbul, Turkey , Ocak, Meltem İstanbul University Faculty of Pharmacy - Department of Pharmaceutical Technology - İstanbul, Turkey
Abstract :
The aim of the study was to estimate the radiation-absorbed doses and to study the in vivo and in vitro stability as well as pharmacokinetic characteristics of lutetium-177 (Lu-177) prostate-specific membrane antigen (PSMA)-617.Methods: For this purpose, 7 patients who underwent Lu-177-PSMA therapy were included into the study. The injected Lu-177-PSMA-617 activity ranged from 3.6 to 7.4 GBq with a mean of 5.2±1.8 GBq. The stability of radiotracer in saline was calculated up to 48 h. The stability was also calculated in blood and urine samples. Post-therapeutic dosimetry was performed based on whole body and single photon emission computed tomography/computed tomography (SPECT/CT) scans on dual-headed SPECT/CT system.Results: The radiochemical yield of Lu-177-PSMA-617 was >99%. It remained stable in saline up to 48 h. Analyses of the blood and urine samples showed a single radioactivity peak even at 24 hours after injection. Half-life of the distribution and elimination phases were calculated to be 0.16±0.09 and 10.8±2.5 hours, respectively. The mean excretion rate was 56.5±8.8% ranging from 41.5% to 65.4% at 24 h. Highest radiation estimated doses were calculated for parotid glands and kidneys (1.90±1.19 and 0.82±0.25 Gy/GBq respectively). Radiation dose given to the bone marrow was significantly lower than those of kidney and parotid glands (p<0.05) (0.030±0.008 Gy/GBq).Conclusion: Lu-177-PSMA-617 is a highly stable compound both in vitro and in vivo. Lu-177-PSMA-617 therapy seems to be a safe method for the treatment of castration-resistant prostate cancer patients. The fractionation regime that enables the longest duration of tumor control and/or survival will have to be developed in further studies.
Keywords :
radionuclide therapy , Lu-177-PSMA , prostate-specific membrane antigen , castration-resistant prostate cancer , PSMA , prostate cancer