Revision of the Histopathological Examination Following 68Ga-DOTA-FAPI-04 PET/CT of a Breast Tumor Diagnosed as Invasive Ductal Carcinomatosis.

Neuroendocrine tumors (NETs) of the breast represent 1% of breast carcinomas. Histopathological misinterpretation of breast NET is common. We present the case of a female patient who had a breast mass diagnosed as invasive ductal carcinoma initially by histopathological examination. Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) revealed 2 ametabolic hypodense liver lesions. Subsequently, the patient underwent fibroblast activation protein inhibitor (FAPI)-PET/CT, which did not reveal any FAP expression in the liver lesions, but increased FAP expression was observed in the soft tissue mass of the mesenteric root. Consequently, the pathology of the biopsy taken from the nodule in the right breast was revised, and a diagnosis of grade 2 NET was established. The benefit of FAPI-PET/CT on NETs has been previously investigated. Further prospective studies are required to establish the role of FAPI-PET/CT in NET management.

Prediction of clinically significant prostate cancer by [68 Ga]Ga-PSMA-11 PET/CT: a potential tool for selecting patients for active surveillance.

PURPOSE: In our study, our aim was to investigate the role of [68 Ga]Ga-PSMA-11 PET /CT imaging in the diagnosis of clinically significant prostate cancer (csPCa) (ISUP GG 2 and higher) in patients initially diagnosed with ISUP GG 1 and 2 after prostate biopsy. MATERIALS AND METHODS: We retrospectively reviewed 147 patient records in whom [68 Ga]Ga-PSMA-11 PET/CT imaging was performed preoperatively. All patients were initially diagnosed with ISUP GG 1 and 2 PCa by biopsy. Final pathology reports were obtained after radical prostatectomy. The [68 Ga]Ga-PSMA-11 PET/CT images were evaluated to determine the PRIMARY score. Patients' mpMRI-PIRADS scores were also recorded when available and analyzed in correlation with the pathology results. RESULTS: For the 114 patients scored using PRIMARY, 19 out of 37 patients with scores of 1 and 2 (51%) were diagnosed with csPCa. Of the 77 patients with PRIMARY scores between 3 and 5, 64 (83%) had csPCa. Notably, every patient with a PRIMARY score of 5 had csPCa. PRIMARY scoring had a sensitivity of 77% and specificity of 58%, with a positive predictive value of 83%. A moderate correlation was observed between PRIMARY scores and ISUP GG (Rho = 0.54, p < 0.001). In contrast, the PIRADS score displayed a sensitivity and specificity of 86% and 25% respectively, with a positive predictive value of 68%. No substantial correlation was found between PIRADS and ISUP GG. Statistical analysis revealed a significant correlation between PRIMARY and ISUP GG (p < 0.001), but not between PIRADS and ISUP GG (p = 0.281). Comparatively, PRIMARY scoring was significantly more reliable than PIRADS scoring in identifying csPCa. CONCLUSION: [68 Ga]Ga-PSMA-11 PET/CT imaging is promising for distinguishing high-risk prostate cancer patients from those apt for active surveillance, potentially aiding in the identification of csPCa.

Initial Findings on the Use of [225Ac]Ac-DOTATATE Therapy as a Theranostic Application in Patients with Neuroendocrine Tumors.

Objectives: This study aimed to evaluate the stability, safety, and efficacy of alpha-targeted therapy with [225Ac]Ac-DOTATATE in patients with grade 1/2 metastatic neuroendocrine tumors (NETs). Methods: This retrospective cohort included patients (n=11) with metastatic NETs from different primary sites (bronchial, pancreatic, nonpancreatic gastroenteropancreatic NETs, paraganglioma, and unknown primary site) treated with [225Ac]Ac-DOTATATE with a mean activity of 8.2±0.6 MBq (range: 7.5-10.0 MBq) at our institution between November 2019 and March 2022. The in vivo and in vitro stability of [225Ac]Ac-DOTATATE was calculated. The safety profile was evaluated according to the CTCAE-v5.0. Treatment efficacy was evaluated according to [68Ga] Ga-DOTATATE positron emission tomography/computed tomography (PET/CT) images and the RECIST 1.1 criteria. Results: Patients had 73% (n=8) lymph node metastases, 91% (n=10) liver metastases, 36% (n=4) lung metastases, and 73% (n=8) bone metastases. All but one patient was refractory to treatment with [177Lu]Lu-DOTATATE. [225Ac]Ac-DOTATATE was stable for at least 5 h in vitro (in saline) and 3 h in vivo (urine and blood samples). Grade 2 renal toxicity and grade 2 hematotoxicity were observed in one patient. No grade 3-4 toxicities were reported. According to post-treatment [68Ga]Ga-DOTATATE PET/CT (n=9), 11% (n=1) had progressive disease, 44.4% (n=4) had stable disease, and 44.4% (n=4) had a partial response. The disease control rate was 89% (n=8). The median progression-free survival estimated according to Kaplan-Meier analysis was 12 months. Conclusion: The preliminary results of this study suggest that [225Ac]Ac-DOTATATE is stable, safe, and effective for treating advanced and [177Lu] Lu-DOTATATE-refractory NETs. However, prospective studies are needed to determine the impact of treatment on overall survival and to uncover potential side effects.

Clinical Experience with [225Ac]Ac-PSMA Treatment in Patients with [177Lu]Lu-PSMA-Refractory Metastatic Castration-Resistant Prostate Cancer.

For patients with advanced-stage metastatic castration-resistant prostate cancer (mCRPC) who do not respond to [177Lu]Lu-PSMA therapy, there are limited treatment options. Clinical results obtained with [225Ac]Ac-PSMA are promising. We retrospectively analyzed the outcomes of patients treated with [225Ac]Ac-PSMA between December 2018 and October 2022. Methods: We evaluated the treatment results of 23 patients (mean age, 70.3 ± 8.8 y) with mCRPC who were refractory to treatment with [177Lu]Lu-PSMA (2-9 cycles). The safety profile was assessed according to Common Technology Criteria for Adverse Events version 5.0. Treatment efficacy was assessed using prostate-specific membrane antigen PET progression criteria and prostate-specific antigen (PSA) response according to Prostate Cancer Working Group 2 criteria after the first cycle of [225Ac]Ac-PSMA treatment. Results: All patients received androgen-deprivation therapy, whereas 22 (96%) and 19 (83%) patients received chemotherapy and second-generation antiandrogen therapy, respectively. One patient received 4 cycles, 2 received 3 cycles, 8 received 2 cycles, and 12 received 1 cycle of [225Ac]Ac-PSMA. The median interval between cycles was 13 wk (range, 8-28 wk). [225Ac]Ac-PSMA was administered with a mean activity of 7.6 MBq (range, 6.2-10.0 MBq) in each cycle. Patients were at an advanced stage of disease, and tumor burden was very high. Although the best PSA response was observed in 5 patients (26%) after [225Ac]Ac-PSMA treatment, there was at least some level of decline in PSA observed in 11 patients (58%; n = 19). Treatment response was assessed in patients who underwent [68Ga]Ga-PSMA PET/CT imaging. After the first cycle of treatment (n = 18), 50% of patients (n = 9) showed disease progression according to prostate-specific membrane antigen PET progression criteria, and the disease control rate was calculated to be 50%. Median progression-free survival was 3.1 mo, and median overall survival was 7.7 mo. Grade 3 hematologic toxicity occurred in 1 patient, and grade 3 nephrotoxicity was observed in another patient. Parotid SUVmax decreased by 33%, although all patients complained of dry mouth before treatment. Conclusion: We observed that [225Ac]Ac-PSMA therapy was safe and showed potential even in cases with advanced-stage mCRPC in which all other treatment options were completed.