Radioligand therapy with <sup>177</sup>Lu-DOTA-PSMA in metastatic castration-resistant prostate cancer. Pharmacokinetics, safety, antitumour efficacy

INTRODUCTION: The results of studies of clinical potential of a new domestic radiopharmaceutical 177Lu-DOTA-PSMA in patients with metastatic castration-resistant prostate cancer are presented in this article.OBJECTIVE: The pharmacokinetics, safety and tolerability of radiopharmaceutical were studied. Tolerability of increasing activities — 5.0, 7.5 and 10.0 GBq was investigated.MATERIALS AND METHODS: The study included 12 patients with metastatic castration-resistant prostate cancer, who progressed after previous treatment. The first 4 patients was treated by 5 GBq of 177Lu DOTA-PSMA, the next 4 patients of the second group was treated by 7.5 GBq, and the 4 patients of the third group was treated by 10 GBq. Radiopharmacokinetics was studied by whole-body scintigraphy, SPECT/CT, blood and urine radiometry. The radiation-absorbed dose (RAD) of metastases and organs at risk was studied by clinical dosimetry. Safety assessment also was studied by hematological status. All patients was taken a complete blood count, a biochemical blood test before course of therapy treatable and during the case study.RESULTS: Study data showed high accumulation of 177Lu-DOTA-PSMA the in pathological focus, the distribution in the body conformed to the previous data of PET/CT study. Blood radiometry showed that 177Lu-DOTA-PSMA rapidly excreted from the bloodstream (during the first hours after injection). Urine radiometry showed that, more than half of the injected dose was excreted during 2 days (from 34.4% to 88.8%).DISCUSSION: During the study was solicited increasing of pain syndrome, dry mouth. Most patients had moderate myelosuppression. Changes in hematological parameters had a transistor character, the adverse event resolved without consequences in 5 week. 4th grade of NCI CTCAE hematological toxicity criteria wasn’t identified. Serious adverse events weren’t identified too.CONCLUSIONS: Radiopharmaceutical demonstrated high affinity for tumor tissue and safety in the clinical use. Data, which demonstrating a high potential anti-tumor efficacy of radiopharmaceutical, were obtained. Dosimetric studies showed radiation safety of work with radiopharmaceutical for the personnel.