Purpose The aim of this study was to evaluate the efficacy and safety of 177Lu-PSMA-617 radioligand therapy in metastatic castration-resistant prostate cancer (mCRPC). Methods In this prospective, single-arm, single-institutional study, 90 mCRPC patients with progressive disease (PD) on second-line hormonal therapy and/or docetaxel chemotherapy were recruited for the study. All patients underwent diagnostic 68Ga-PSMA-HBED-CC PET/CT, prior to inclusion for therapy. Included patients underwent 177Lu-PSMA-617 therapy at 8- to 12-weekly intervals. The primary end point was to assess the overall survival. The secondary and cosecondary end points included biochemical response assessment as per the Prostate Cancer Working Group 3 criteria, progression-free survival, radiological and molecular response criteria, clinical response, safety profile, and disease control rates. All the outcome parameters were evaluated in 90 patients except for the radiographic and molecular response, which was evaluated in 69 patients. Results The median age of patients was 66.5 years (range, 30–88 years). The median activity administered per cycle was 3.7 to 8 GBq ranging from 1 to 7 cycles, and patients were followed up over a median duration of 28 months. At 2- to 3-month interval after the first therapy and the end of the assessment, greater than 50% decline in prostate-specific antigen was observed in 32.2% and 45.5%, respectively. Univariate analysis did not reveal any variables such as prior therapies, laboratory parameters, concomitant hormonal therapy, and SUV patient parameters associated with prostate-specific antigen decline. Radiographic response by diagnostic CT revealed partial remission in 23% (16/69), stable disease in 54% (37/69), and PD in 23% (16/69) of patients. Molecular tumor response by PET Response Criteria in Solid Tumor 1 criteria revealed 19 (27.5%) of 69 patients with partial remission, 30 (43.5%) of 69 with stable disease, and 20 (29%) of 69 with PD. The disease control rates according to the radiographic and molecular response were 77% and 71%, respectively. The median overall survival and median progression-free survivals were 14 and 11.8 months, respectively. Toxicities related to radioligand therapy were low and transient with no serious adverse effects. Conclusions 177Lu-PSMA-617 radionuclide therapy is a safe and effective approach to the treatment of mCRPC patients.

The aim of this study was to compare the grading and prognostic value of L-[methyl-11 C]-methionine ( 11 C-MET) PET in glioma patients with 18 F-FDG PET and contrast-enhanced MRI. Methods: Patients (n 5 102) with histopathologically confirmed gliomas were followed up for an average of 34.6 6 3.8 mo after PET. The median survival was 18 6 4.7 mo in the high-grade glioma group and 58 6 27 mo in the low-grade glioma group. Patients underwent 18 F-FDG PET, 11 C-MET PET, and MRI in the diagnostic and preoperative stage. The ratio of the mean standardized uptake value in the tumor to mean standardized uptake value in contralateral normal cortex (T/N ratio) was calculated. Kaplan-Meier survival analysis and ANOVA were performed. Results: T/N ratios for 11 C-MET PET and 18 F-FDG PET were significantly higher in high-grade gliomas than in low-grade gliomas (2.15 6 0.77 vs. 1.56 6 0.74, P , 0.001, and 0.85 6 0.61 vs. 0.63 6 0.37, P , 0.01, respectively). Median survival was 19 6 5.4 mo in patients with a T/N ratio greater than 1.51 for 11 C-MET PET and 58 6 26.7 mo in those with a T/N ratio less than 1.51 (P 5 0.03). Among the LGGs, median survival was lower in patients with a mean T/N ratio greater than 1.51 for 11 C-MET PET (16 6 10 mo; 95% confidence interval, 1-36 mo) than in those with a T/N ratio less than 1.51 (P 5 0.04). No significant difference in survival in LGGs was based on 18 F-FDG uptake and MRI contrast enhancement. Conclusion: 11 C-MET PET can predict prognosis in gliomas and is better than 18 F-FDG PET and MRI in predicting survival in LGGs.

Gallium-68-DOTA-NOC PET/CT appears to be a highly sensitive and specific modality for the detection of gastroenteropancreatic NET. It is better than conventional imaging for the evaluation of gastroenteropancreatic NETs and can have a significant impact on patient management.