Purpose: With the increasing detection rate of early prostate cancer (PCa), the proportion of surgical treatment is increasing. Surgery is the most effective treatment for PCa. Precise targeting of tumors during surgery can reduce the incidence of positive surgical margins (PSMs) and preserve the neurovascular bundles (NVBs) as much as possible. The objective of this study was to synthesize a PSMA fluorescent probe (PSMA-Cy5) and verify the targeting specificity of the probe for prostate cancer, thereby providing a theoretical basis for the development of PSMA fluorescent probes for clinical application in the future. Methods: In this study, a novel water-soluble 3H-indocyanine-type bioluminescent dye-Cy5-labeled prostate-specific membrane antigen (PSMA) ligand (PSMA-Cy5) was synthesized by liquid phase synthesis. The PSMA ligand was developed based on the glutamine-urea-lysine (Glu-urea-Lys) structure. The new fluorescent probe was evaluated in vitro and in vivo, and its safety was evaluated. Confocal microscopy was used to observe the binding uptake of PSMA-Cy5 with PSMA (+) LNCaP cells, PSMA (-) PC3 cells and blocked LNCaP cells. In in vivo optical imaging studies, the targeting specificity of PSMA (+) 22Rv1 tumors to probe binding was validated by tail vein injection of PSMA-Cy5. The safety of the PSMA-Cy5 probe was evaluated by histopathological analysis of mouse organs by a single high-dose tail vein injection of PSMA-Cy5. Results: In vitro fluorescence cell uptake experiments showed that the binding of PSMA-Cy5 to LNCaP cells has targeting specificity. PC3 cells and blocked LNCaP cells showed almost no uptake. The results of in vivo optical imaging studies showed that the tumor-to-background ratio in the 22Rv1 group was 3.39 ± 0.47; in the 22Rv1 blocking group it was 0.78 ± 0.15, and in the PC3 group it was 0.94 ± 0.09, consistent with the in vitro results. After a high-dose injection of PSMA-Cy5, there were no abnormalities in the tissues or organs of the mice. The probe showed good safety. Conclusions: PSMA-Cy5 is a probe with good targeting specificity and low toxicity that can accurately visualize tumors in vivo. This study has an important reference value for the development of PSMA fluorescent probes. In the future, it can be applied to precise tumor imaging during radical prostatectomy to reduce the incidence of postoperative PSM.

This study aims to investigate the efficacy and safety of prostate-specific membrane antigen (PSMA) radiolabeled with copper-64 (⁶⁴Cu) using the bifunctional chelating agents (BFCAs) NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid) and DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid). As widely utilized BFCAs in the development of radiopharmaceuticals, NOTA and DOTA play a critical role in ensuring stable chelation with ⁶⁴Cu. This study evaluates the stability, bioavailability, and therapeutic potential of these radiolabeled compounds in preclinical models and initial clinical trials. ⁶⁴Cu-DOTA-PSMA-3Q and ⁶⁴Cu-NOTA-PSMA-3Q were synthesized by manual labeling. The radiochemical purity, stability, specificity and biological distribution of the product were evaluated by preclinical studies. In 23 patients with suspected prostate cancer, PET/CT imaging was used to evaluate the potential and differences in biological distribution of ⁶⁴Cu-DOTA-PSMA-3Q and ⁶⁴Cu-NOTA-PSMA-3Q in clinical diagnosis. The radiochemical purities of ⁶⁴Cu-DOTA-PSMA-3Q and ⁶⁴Cu-NOTA-PSMA-3Q are more than 98% and have good stability in vitro. Biodistribution studies in healthy mice revealed that both tracers primarily underwent renal excretion post-injection. Liver uptake of ⁶⁴Cu-DOTA-PSMA-3Q was significantly higher than that of ⁶⁴Cu-NOTA-PSMA-3Q at 1 h after injection (P0.05). However, after 24 h, ⁶⁴Cu-DOTA-PSMA-3Q exhibited significantly better tumor retention compared to ⁶⁴Cu-NOTA-PSMA-3Q (P<0.05). In clinical PET/CT imaging involving 23 patients with suspected prostate cancer, no adverse reactions or significant changes in vital signs were observed, underscoring the safety of both tracers. Notably, ⁶⁴Cu-NOTA-PSMA-3Q demonstrated higher uptake in the lacrimal glands (17.73 vs. 10.84), parotid glands (20.98 vs. 16.30), and submandibular glands (20.26 vs. 17.28) compared to ⁶⁴Cu-DOTA-PSMA-3Q. Conversely, uptake in the sublingual glands was lower for ⁶⁴Cu-NOTA-PSMA-3Q (7.10 vs. 7.49). Of particular clinical relevance, liver uptake of ⁶⁴Cu-NOTA-PSMA-3Q was significantly lower than that of ⁶⁴Cu-DOTA-PSMA-3Q (4.04 vs. 8.18), highlighting a key difference in their biodistribution profiles. Both NOTA and DOTA are suitable chelators for the development of ⁶⁴Cu-labeled PSMA-3Q tracers for PET/CT imaging. DOTA showed better tumor retention 24 h after injection, while NOTA showed lower uptake in the liver, in addition, NOTA was higher uptake in the salivary glands, while DOTA was lower uptake in these tissues. Overall, these findings highlight the importance of selecting the right chelating agent to optimize clinical imaging outcomes. Chinese Clinical Trial Registry ChiCTR2300072655, Registered 20 June 2023.

Castleman’s disease (CD) is a primary lymphoproliferative disorder of the lymph nodes with rare extra-nodal primary affection. Solid organ involvement is rare, and isolated liver involvement is extremely rare. Here we presented a case of a 59-year-old woman with a hepatic lesion accidentally found by ultrasound. The MRI result indicated primary liver malignancy or liver metastases. ¹⁸F-FDG PET/CT could not exclude hepatic malignant tumor due to its high metabolism. Finally, the hepatic CD was confirmed by postoperative pathology.

Primary prostatic stromal sarcoma is extremely rare. Serum PSA is usually normal. Here, we report a case of primary prostatic stromal sarcoma in a 23-year-old man. ¹⁸F–prostate-specific membrane antigen (PSMA) PET/CT showed prostate mass and multiple low-density lesions in the liver with high PSMA expression. However, after chemotherapy, the level of PSMA expression in the prostate mass decreased, and PSMA expression lesions in the liver disappeared.

Desmoplastic small round cell tumor (DSRCT) as a subtype of sarcoma is rare and aggressive. We present the case of a 23-year-old man with a histologically confirmed DSRCT who underwent ¹⁸F-PSMA PET/CT before prostate biopsy and surgical resection of the tumor. It is well known that PSMA PET has a high accuracy for detecting clinically significant prostate adenocarcinoma and is useful in guiding prostate biopsy. This case signifies DSRCT can also exhibit intermediate PSMA expression on ¹⁸F-PSMA PET/CT.

Background/Objectives: During prostate cancer progression, downregulation or loss of prostate-specific membrane antigen (PSMA) expression, together with interlesional heterogeneity, may limit the efficacy of PSMA-targeted radioligand therapy. Fibroblast activation protein (FAP), expressed mainly by activated cancer-associated fibroblasts in the tumor microenvironment, represents a potential complementary target. We developed the PSMA/FAP bispecific radioligand with a biphenyl scaffold and evaluated its feasibility and therapeutic potential. Methods: The radiochemical purity and in vitro stability were evaluated by Radio-HPLC. Cellular uptake was evaluated in 22Rv1 (PSMA+), U87MG (FAP+), and PC-3 (PSMA−/FAP−) cells. SPECT/CT imaging and biodistribution studies were performed using mice bearing separate 22Rv1 (PSMA+) and U87MG (FAP+) xenografts. Therapeutic efficacy was assessed after a single administration of 30 or 60 MBq [¹⁷⁷Lu]Lu-PSFA-1, together with an acute toxicity evaluation. Results: [¹⁷⁷Lu]Lu-PSFA-1 showed PSMA- and FAP-associated uptake. SPECT/CT imaging and biodistribution studies showed persistent uptake in both tumor types, with higher uptake in U87MG tumors and increasing tumor-to-background ratios over time. A single administration of 30 or 60 MBq delayed tumor growth and prolonged survival, with more durable tumor control at 60 MBq. No evident acute toxicity was observed. Conclusions: [¹⁷⁷Lu]Lu-PSFA-1 specifically targeted both PSMA- and FAP-positive tumors, with sustained tumor retention and antitumor activity. These findings support further evaluation of [¹⁷⁷Lu]Lu-PSFA-1 as a PSMA/FAP bispecific radioligand, although its potential benefit in heterogeneous prostate cancer requires further validation.