Diagnostic value of retrospectively fused 64CuCl2 PET/MRI in biochemical relapse of prostate cancer: comparison with fused 18F-Choline PET/MRI, 64CuCl2 PET/CT, 18F-Choline PET/CT, and mpMRI

Role of 64CuCl2 PET/CT in Detecting and Staging Muscle-Invasive Bladder Cancer: Comparison with Contrast-Enhanced CT and 18F-FDG PET/CT

Molecular imaging of muscle-invasive bladder cancer (MBC) is restricted to its locoregional and distant metastases, since most radiopharmaceuticals have a urinary excretion that limits the visualization of the primary tumor. 64CuCl2 , a positron-emitting radiotracer with nearly exclusive biliary elimination, could be well suited to exploring urinary tract neoplasms. In this study, we evaluated the feasibility of 64CuCl2-based staging of patients with MBC; furthermore, we compared the diagnostic capability of this method with those of the current gold standards, that is, contrast-enhanced CT (ceCT) and 18F-FDG PET/CT. Methods: We prospectively enrolled patients referred to our institution for pathology-confirmed MBC staging/restaging between September 2021 and January 2023. All patients underwent ceCT, 18F-FDG, and 64CuCl2 PET/CT within 2 wk. Patient-based analysis and lesion-based analysis were performed for all of the potentially affected districts (overall, bladder wall, lymph nodes, skeleton, liver, lung, and pelvic soft tissue). Results: Forty-two patients (9 women) were enrolled. Thirty-six (86%) had evidence of disease, with a total of 353 disease sites. On patient-based analysis, ceCT and 64CuCl2 PET/CT showed higher sensitivity than 18F-FDG PET/CT in detecting the primary tumor (P < 0.001); moreover, 64CuCl2 PET/CT was slightly more sensitive than 18F-FDG PET/CT in disclosing soft-tissue lesions (P < 0.05). Both PET methods were more specific and accurate than ceCT in classifying nodal lesions (P < 0.05). On lesion-based analysis, 64CuCl2 PET/CT outperformed 18F-FDG PET/CT and ceCT in detecting disease localizations overall (P < 0.001), in the lymph nodes (P < 0.01), in the skeleton (P < 0.001), and in the soft tissue (P < 0.05). Conclusion: 64CuCl2 PET/CT appears to be a sensitive modality for staging/restaging of MBC and might represent a "one-stop shop" diagnostic method in these scenarios.

Unveiling the promising anticancer effect of copper-based compounds: a comprehensive review

Copper is a necessary micronutrient for maintaining the well-being of the human body. The biological activity of organic ligands, especially their anticancer activity, is often enhanced when they coordinate with copper(I) and (II) ions. Copper and its compounds are capable of inducing tumor cell death through various mechanisms of action, including activation of apoptosis signaling pathways by reactive oxygen species (ROS), inhibition of angiogenesis, induction of cuproptosis, and paraptosis. Some of the copper complexes are currently being evaluated in clinical trials for their ability to map tumor hypoxia in various cancers, including locally advanced rectal cancer and bulky tumors. Several studies have shown that copper nanoparticles can be used as effective agents in chemodynamic therapy, phototherapy, hyperthermia, and immunotherapy. Despite the promising anticancer activity of copper-based compounds, their use in clinical trials is subject to certain limitations. Elevated copper concentrations may promote tumor growth, angiogenesis, and metastasis by affecting cellular processes.

Targeting Copper in Cancer Imaging and Therapy: A New Theragnostic Agent

Copper is required for cancer cell proliferation and tumor angiogenesis. Copper-64 radionuclide (⁶⁴Cu), a form of copper chloride (⁶⁴CuCl₂), is rapidly emerging as a diagnostic PET/CT tracer in oncology. It may also represent an interesting alternative to gallium-68 (⁶⁸Ga) as a radionuclide precursor for labelling radiopharmaceuticals used to investigate neuroendocrine tumors and prostate cancer. This emerging interest is also related to the nuclear properties of ⁶⁴CuCl₂ that make it an ideal theragnostic nuclide. Indeed, ⁶⁴CuCl₂ emits β⁺ and β^- particles together with high-linear-energy-transfer Auger electrons, suggesting the therapeutic potential of ⁶⁴CuCl₂ for the radionuclide cancer therapy of copper-avid tumors. Recently, ⁶⁴CuCl₂ was successfully used to image prostate cancer, bladder cancer, glioblastoma multiforme (GBM), and non-small cell lung carcinoma in humans. Copper cancer uptake was related to the expression of human copper transport 1 (hCTR1) on the cancer cell surface. Biodistribution, toxicology and radiation safety studies showed its radiation and toxicology safety. Based on the findings from the preclinical research studies, ⁶⁴CuCl₂ PET/CT also holds potential for the diagnostic imaging of human hepatocellular carcinoma (HCC), malignant melanoma, and the detection of the intracranial metastasis of copper-avid tumors based on the low physiological background of radioactive copper uptake in the brain.

Recent Advances in Cancer Imaging with 64CuCl2 PET/CT

Copper is required for cancer cell proliferation and tumor angiogenesis. Radioactive copper-64 chloride (⁶⁴CuCl₂) is a useful radiotracer for cancer imaging with position emission tomography (PET) based on increased cellular uptake of copper mediated by human copper transporter 1 (hCtr1) expressed on cancer cell membrane. Significant progress has been made in research of using ⁶⁴CuCl₂ as a radiotracer for cancer imaging with PET. Radiation dosimetry study in humans demonstrated radiation safety of ⁶⁴CuCl₂. Recently, ⁶⁴CuCl₂ was successfully used for PET imaging of prostate cancer, bladder cancer, glioblastoma multiforme (GBM), and non-small cell lung carcinoma in humans. Based on the findings from the preclinical research studies, ⁶⁴CuCl₂ PET/CT also holds potential for diagnostic imaging of human hepatocellular carcinoma (HCC), malignant melanoma, and detection of intracranial metastasis of copper-avid tumors based on low physiological background of radioactive copper uptake in the brain. Copper-64 radionuclide emits both β⁺ and β^- particles, suggesting therapeutic potential of ⁶⁴CuCl₂ for radionuclide cancer therapy of copper-avid tumors. Recent progress in production of therapeutic copper-67 radionuclide invites clinical research in use of theranostic pair of ⁶⁴CuCl₂ and ⁶⁷CuCl₂ for cancer imaging and radionuclide therapy.

A Prospective Study Assessing the Post-Prostatectomy Detection Rate of a Presumed Local Failure at mpMR with Either 64CuCl2 or 64CuPSMA PET/CT

Simple Summary

The role of PET/CT with two novel tracers was investigated in prostate cancer patients with both a biochemical failure after surgery and a presumed local failure at multiparametric MR. Overall, both PET tracers detected only about 50% of local failures. Therefore, multiparametric MR remains the exam of choice to investigate the prostatic fossa in patients who fail surgery.

Abstract

Background: We aimed assess the detection rate (DR) of positron emission tomography/computed tomography with two novel tracers in patients referred for salvage radiotherapy (sRT) with a presumed local recurrence at multiparametric magnetic resonance (mpMR) after radical prostatectomy (RP). Methods: The present prospective study was conducted at a single institution between August 2017 and June 2020. Eligibility criteria were undetectable PSA after RP; subsequent biochemical recurrence (two consecutive PSA rises to 0.2 ng/mL or greater); a presumed local failure at mpMR; no distant metastases at ¹⁸F-fluorocholine PET/CT (CH/PET); no previous history of androgen deprivation therapy. Patients were offered both ⁶⁴CuCl₂ PET/CT (CU/PET) and ⁶⁴Cu-PSMA PET/CT (PSMA/PET) before sRT. After image co-registration, PET findings were compared to mpMR ones in terms of DR and independent predictors of DR investigated at logistic regression. Results: A total of 62 patients with 72 nodules at mpMR were accrued. Compared to mpMR (DR = 100%, 95%CI: 94.9–100%), DRs were 47.2% (95%CI: 36.1–58.6%) and 54.4% (95%CI: 42.7–65.7%) for CU/PET and PSMA/PET, respectively (p < 0.001 for both). Both experimental PET/CT performed particularly poorly at PSA levels consistent with early sRT. Conclusions: The two novel radiotracers are inferior to mpMR in restaging the prostatic fossa for sRT planning purposes, particularly in the context of early salvage radiotherapy.

Long Non-Coding RNA (lncRNA) RAMS11 Promotes Metastatis and Cell Growth of Prostate Cancer by CBX4 Complex Binding to Top2α

Introduction

Studies have confirmed that parts of the non-coding genes in the human genome play an important role in the pathogenesis and metastasis of prostate cancer. Among them, long non-coding RNAs (lncRNAs) are vitally involved in the biological regulation of prostate cancer. In addition, lncRNAs are closely associated with the recurrence, metastasis and prognosis of prostate cancer. However, the molecular pathogenesis of lncRNAs in regulating cell growth and metastasis of prostate cancer remains unclear. Therefore, this study was designed to explore the function and mechanism of lncRNA RAMS11 in cell growth and metastasis of prostate cancer.

Methods

Prostate cancer and para-carcinoma tissue samples were obtained from 42 patients who were diagnosed from March 2013 to September 2014 at Quanzhou First Hospital Affiliated to Fujian Medical University. Microarray experiments and real-time polymerase chain reaction (PCR) measured the expression of lncRNA. RWPE-2, LNCap, PC3 and DU145 cells were used for an in vitro model.

Results

The expression of lncRNA RAMS11 was up-regulated in prostate cancer tissue samples. LncRNA RAMS11 promoted cell growth and metastasis of prostate cancer cells. Down-regulation of lncRNA RAMS11 attenuated cell growth and metastasis of prostate cancer cells. We also demonstrated that lncRNA RAMS11 bound to CBX4 to activate expression of Top2α. LncRNA RAMS11 promoted tumor growth of prostate cancer in the mouse model. The inhibition of CBX4 attenuated the pro-cancer effects of lncRNA AMS11 in prostate cancer cells, while the activation of Top2α attenuated the anti-cancer effects of si-lncRNA RAMS11 in prostate cancer cells.

Discussion

Our results indicated that lncRNA RAMS11 promoted cell growth and metastasis of prostate cancer by CBX4 complex via binding to Top2α, and might be developed for the treatment of prostate cancer.

Copper-64 Chloride Exhibits Therapeutic Potential in Three-Dimensional Cellular Models of Prostate Cancer

Prostate cancer (PCa) is the second most common cancer type in men, and in advanced metastatic stages is considerable incurable. This justifies the need for efficient early diagnostic methods and novel therapies, particularly radiopharmaceuticals with the potential for simultaneous diagnosis and therapy (theranostics). We have previously demonstrated, using monolayer-cultured cells, that copper-64 chloride, a promising theranostic agent for PCa, has the potential to induce significant damage in cancer cells while having minimal side effects in healthy tissues. Here, we further explored this compound for its theranostic applications using more advanced PCa cellular models, specifically multicellular spheroids. Namely, we evaluated the cellular uptake of ⁶⁴CuCl₂ in three human PCa spheroids (derived from 22RV1, DU145, and LNCaP cells), and characterized the growth profile and viability of those spheroids as well as the clonogenic capacity of spheroid-derived cells after exposure to ⁶⁴CuCl₂. Furthermore, the populations of cancer stem cells (CSCs), known to be important for cancer resistance and recurrence, present in the spheroid models were also evaluated using two different markers (CD44 and CD117). ⁶⁴CuCl₂ was found to have significant detrimental effects in spheroids and spheroid-derived cells, being able to reduce their growth and impair the viability and reproductive ability of spheroids from both castration-resistant (22RV1 and DU145) and hormone-naïve PCa (LNCaP). Interestingly, resistance to ⁶⁴CuCl₂ treatment seemed to be related with the presence of a CSC population, since the most resistant spheroids, derived from the DU145 cell line, had the highest initial percentage of CSCs among the three cell lines under study. Altogether, these results clearly highlight the theranostic potential of ⁶⁴CuCl₂.

Copper, PET/CT and prostate cancer: a systematic review of the literature

Copper is an essential element that plays an important role in both cancer development and growth. Indeed, high levels of copper have been found in prostate cancer (PCa), and this finding have paved the way for the use of this element as a target for positron emission tomography (PET) imaging. Copper64 (64Cu) can be used alone, as 64CuCl2, and also as a precursor for the in-vitro radio-labelling of specific carriers for PET imaging in PCa, (e.g. associated to prostate-specific membrane antigen: PSMA). The use of 64Cu-PSMA can yield late acquisitions in which PET images are characterized by a higher target-to-background ratio. At the same time, the shorter positron range of 64Cu provides high spatial resolution, which leads to better detection of small lesions. In this context, the aim of this review was to systematically review studies evaluating the identification of PCa in humans by means of 64CuCl2 and other PET tracers radio-labelled with 64Cu.