Safety and efficacy of 177Lu-PSMA-617 therapy in metastatic castration-resistant prostate cancer

Objective To investigate the safety and efficacy of 177Lu-prostate specific membrane antigen (PSMA)-617 in the treatment of metastatic castration-resistant prostate cancer (mCRPC). Methods From August 2017 to September 2018, 11 patients(average age 70.6 years) with mCRPC who underwent 177Lu-PSMA-617 therapy in Nanjing First Hospital were studied. All patients underwent 68Ga-PSMA-11 PET/CT before therapy to assess the tumor radioactive uptake. Blood routine examination and renal function test results were documented before and after therapy to assess the safety. The efficacy was reflected by the changes of prostate specific antigen (PSA) levels and maximum standardized uptake value (SUVmax) on 68Ga-PSMA-11 PET/CT imaging. Paired t test and Wilcoxon′s sign rank test were used to analyze the data. Results No acute side effects were observed after therapy of 177Lu-PSMA-617. There were no statistically significant differences after therapy in WBC counts, RBC counts, and PLT, as well as Hb levels (t values: -0.28-1.11, all P>0.05). No kidney toxicity was found. The PSA level after 177Lu-PSMA-617 therapy was significantly lower than that before therapy (80.70(14.29, 1 538.00) μg/L vs 604.60(88.41, 3 980.00) μg/L; u=59, P=0.023). Of the 11 patients, only 2 had elevated PSA levels and disease progression, while the other 9 patients had varying decreases, of which 2/11 decreased by >30% and 7/11 decreased by >50%. After therapy, SUVmax of metastatic lesions and metastatic lymph nodes were decreased in 9 and 2 patients respectively. Conclusions 177Lu-PSMA-617 has a good therapeutic value for mCRPC. It is safe and has no obvious side effects. Key words: Prostatic neoplasms, castration-resistant; Prostate-specific membrane antigen; Isotope labeling; Lutetium; Radiotherapy; Treatment outcome