Tau induces inflammasome activation and microgliosis through acetylating NLRP3.

BACKGROUND: Alzheimer's disease (AD) and related Tauopathies are characterised by the pathologically hyperphosphorylated and aggregated microtubule-associated protein Tau, which is accompanied by neuroinflammation mediated by activated microglia. However, the role of Tau pathology in microglia activation or their causal relationship remains largely elusive. METHODS: The levels of nucleotide-binding oligomerisation domain (NOD)-like receptor pyrin domain containing 3 (NLRP3) acetylation and inflammasome activation in multiple cell models with Tau proteins treatment, transgenic mice with Tauopathy, and AD patients were measured by Western blotting and enzyme-linked immunosorbent assay. In addition, the acetyltransferase activity of Tau and NLRP3 acetylation sites were confirmed using the test-tube acetylation assay, co-immunoprecipitation, immunofluorescence (IF) staining, mass spectrometry and molecular docking. The Tau-overexpressing mouse model was established by overexpression of human Tau proteins in mouse hippocampal CA1 neurons through the adeno-associated virus injection. The cognitive functions of Tau-overexpressing mice were assessed in various behavioural tests, and microglia activation was analysed by Iba-1 IF staining and [18F]-DPA-714 positron emission tomography/computed tomography imaging. A peptide that blocks the interaction between Tau and NLRP3 was synthesised to determine the in vitro and in vivo effects of Tau-NLRP3 interaction blockade on NLRP3 acetylation, inflammasome activation, microglia activation and cognitive function. RESULTS: Excessively elevated NLRP3 acetylation and inflammasome activation were observed in 3xTg-AD mice, microtubule-associated protein Tau P301S (PS19) mice and AD patients. It was further confirmed that mimics of 'early' phosphorylated-Tau proteins which increase at the initial stage of diseases with Tauopathy, including TauT181E, TauS199E, TauT217E and TauS262E, significantly promoted Tau-K18 domain acetyltransferase activity-dependent NLRP3 acetylation and inflammasome activation in HEK293T and BV-2 microglial cells. In addition, Tau protein could directly acetylate NLRP3 at the K21, K22 and K24 sites at its PYD domain and thereby induce inflammasome activation in vitro. Overexpression of human Tau proteins in mouse hippocampal CA1 neurons resulted in impaired cognitive function, Tau transmission to microglia and microgliosis with NLRP3 acetylation and inflammasome activation. As a targeted intervention, competitive binding of a designed Tau-NLRP3-binding blocking (TNB) peptide to block the interaction of Tau protein with NLRP3 inhibited the NLRP3 acetylation and downstream inflammasome activation in microglia, thereby alleviating microglia activation and cognitive impairment in mice. CONCLUSIONS: In conclusion, our findings provide evidence for a novel role of Tau in the regulation of microglia activation through acetylating NLRP3, which has potential implications for early intervention and personalised treatment of AD and related Tauopathies.

Noninvasive longitudinal PET/CT imaging of CAR T cells using PSMA reporter gene.

PURPOSE: Chimeric antigen receptor (CAR) T cell therapy has achieved great success in treating hematologic malignancies. However, it is yet to prove effective in the treatment of solid tumors. Thus, it is necessary to develop appropriate methodology for the long-term, accurate, and quantitative evaluation of the distribution and activities of CAR T cells in solid tumors. In the present study, we engineered TfR ΔPSMA CAR (CAR-ΔPSMA) T cells, which targeted the transferrin receptor (TfR) expressed by tumor cells and could be tracked in vivo via a reporter gene encoding the truncated prostate specific membrane antigen (ΔPSMA). We then quantitatively monitored these CAR T cells in vitro and in vivo using [68Ga]Ga-PSMA-617 positron emission tomography (PET)/computed tomography (CT). METHODS: The CAR-ΔPSMA T cells were genetically engineered by transducing T cells with a lentiviral vector encoding TfR41BBζ-T2A-ΔPSMA. Firstly, the target expression, activation, and cytotoxicity of CAR-ΔPSMA T cells were validated in vitro. Secondly, the minimum thresholds of CAR-ΔPSMA T cells detection for [68Ga]Ga-PSMA-617 PET/CT were also determined in vitro and in vivo respectively. Lastly, the feasibility of monitoring the biodistribution and infiltration of CAR-ΔPSMA T cells after systematic administration was evaluated in the breast cancer subcutaneous xenograft model. RESULTS: The CAR-ΔPSMA T cells retained activation and tumor killing capacity after transduction of the ΔPSMA-encoding reporter gene. Next, the CAR-ΔPSMA T cells could be reliably tracked by [68Ga]Ga-PSMA-617 PET/CT, the detection sensitivity of which was 250 cells/mm3 in vitro and 100 cells/mm3 in vivo. Next, the sequential imaging assays revealed that [68Ga]Ga-PSMA-617 PET/CT could be used to specifically visualize ΔPSMA+ CAR T cells at the tumor site. The increase in the [68Ga]Ga-PSMA-617 signal intensity over time allowed us to effectively detect CAR T cells in vivo. CONCLUSION: Our findings preliminarily confirmed that [68Ga]Ga-PSMA-617 PET/CT could reliably detect CAR-ΔPSMA T cells in vitro and in vivo in solid tumors, laying the foundation for the monitoring CAR T cell therapy in the future.

Melanin-targeted [18F]-PFPN PET imaging may shed light for clear cell sarcoma.

PURPOSE: Intracytoplasmic melanin pigment is a characteristic of clear cell sarcoma (CCS), which is a particularly deadly type of soft-tissue sarcoma. [18F]-N-(2-(diethylamino)ethyl)-5-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy)picolinamide ([18F]-PFPN) is a positron emission tomography (PET) probe characterized by high melanin affinity. Therefore, this study aimed to investigate the feasibility of melanin-targeted [18F]-PFPN PET in patients with CCS. METHODS: This prospective single-centre study recruited patients with pathologically confirmed CCS. [18F]-FDG PET/computed tomography and [18F]-PFPN PET/magnetic resonance imaging scans were performed within 1 week of each other. The lesion numbers and [18F]-FDG and [18F]-PFPN PET parameters (maximum standardized uptake value [SUVmax], mean standardized uptake value [SUVmean], metabolic/melanotic tumour volume [MTV/MLTV], and total lesion glycolysis/melanin [TLG/TLM]) were collected. RESULTS: Three patients with CCS were recruited and received PET imaging. A total of 56 lesions were detected on [18F]-PFPN PET, including primary tumour and distant metastases. Identical lesions were not detected on [18F]-PFPN and [18F]-FDG PET. Twelve lesions (12/39, 30.77%) on [18F]-FDG imaging were missed on [18F]-PFPN, and 20 lesions (20/47, 42.55%) on [18F]-PFPN imaging were missed on [18F]-FDG. In quantitative analysis, the [18F]-FDG SUVmean (4.60 ± 3.24) was higher than the [18F]-PFPN SUVmean (3.0 ± 2.63) in all lesions (P = 0.01). No significant correlations were found between the SUVmax, SUVmean, MLTV/MTV, and TLM/TLG values of [18F]-PFPN and [18F]-FDG (P > 0.05). CONCLUSION: Melanin-targeted [18F]-PFPN PET imaging is feasible for the diagnosis of CCS. Different imaging features were displayed on [18F]-PFPN and [18F]-FDG PET imaging, demonstrating the complementary role of the tracers. Combined use of the two imaging modalities would be preferred in patients with CCS. CLINICAL TRIAL REGISTRATION: NCT05963035.

Preclinical evaluation of a dual-receptor targeted tracer [68Ga]Ga-HX01 in 10 different subcutaneous and orthotopic tumor models.

PURPOSE: The integrin αvß3 and aminopeptidase N (APN/CD13) play vital roles in the tumor angiogenesis process. They are highly expressed in a variety of tumor cells and proliferating endothelial cells during angiogenesis, which have been considered as highly promising targets for tumor imaging. Arginine-glycine-aspartic (RGD) and asparagine-glycine-arginine (NGR) are two peptides specifically binding to the integrin αvß3 and CD13, respectively. In this study, we optimized our previously developed probe and preclinically evaluated the new integrin αvß3 and CD13 dual-targeted probe, NOTA-RGD-NGR (denoted as HX01) radiolabeled with 68Ga, in 10 different subcutaneous and orthotopic tumor models. METHODS: The specific activity and radiochemical purity of [68Ga]Ga-HX01 were identified. The dual-receptor targeting ability was confirmed by a series of blocking studies and partly muted tracers using BxPC-3 xenograft model. The dynamic imaging study and dose escalation study were explored to determine the optimal imaging time point and dosage in the BxPC-3 xenograft model. Next, we established a variety of subcutaneous and orthotopic tumor models including pancreas (BxPC-3), breast (MCF-7), gallbladder (NOZ), lung (HCC827), ovary (SK-OV-3), colorectal (HCT-8), liver (HuH-7), stomach (NUGC-4), and glioma (U87) cancers. All models underwent [68Ga]Ga-HX01 PET/CT imaging about 2 weeks post-inoculation, with a subset of them undergoing [18F]FDG PET/CT scan performed concurrently, and their results were compared. In addition, ex vivo biodistribution studies were also performed for verifying the semi-quantitative results of the non-invasive PET images. RESULTS: [68Ga]Ga-HX01 significantly outperformed single target probes in the BxPC-3 xenograft model. All blocking and single target groups exhibited significantly descending tumor uptake. The high tumor uptakes were found in BxPC-3, MCF-7, and NOZ subcutaneous tumors (%ID/g > 1.1), while middle uptakes were observed in HCC827, SK-OV-3, HCT-8, and HuH-7 subcutaneous tumor (%ID/g 0.7-1.0). Due to the low background, the tumor-to-muscle and tumor-to-blood ratios of [68Ga]Ga-HX01 were higher than that of [18F]FDG. CONCLUSIONS: [68Ga]Ga-HX01, as a dual target imaging agent, exhibited superior in vivo performance in different subcutaneous and orthotopic mice models of human tumors over [18F]FDG and its respectively mono-receptor targeted agents, which warrants the future clinical translation for tumor imaging.

Melanin-targeted [18F]-PFPN PET imaging for prognosticating patients with melanoma.

PURPOSE: Positron emission tomography (PET) using [18F]-PFPN, a melanin-targeted imaging tracer, has excellent diagnostic performance in patients with melanoma. This study aimed to investigate its value in prognostication and determine predictors of progression-free survival (PFS) and overall survival (OS). METHODS: We reviewed melanoma patients who underwent [18F]-PFPN and [18F]-FDG PET from February 2021 to July 2022. Clinical characteristics, follow-up data, and the following [18F]-PFPN PET parameters were recorded: maximum standardized uptake value (SUVmax), whole-body melanotic tumoral volume (WBMTV), and whole-body total lesion melanin (WBTLM). Receiver operating characteristic (ROC), Kaplan-Meier and Cox regression analyses were performed. RESULTS: Seventy-six patients (47 men and 29 women; mean age, 57.99 ± 10.72 years) were included for analysis. Median follow-up was 12.0 months (range: 1-22 months). Eighteen patients died and 38 experienced progression. Median OS was 17.60 months (95% confidence interval, 15.89-19.31). In the ROC analysis, [18F]-PFPN PET parameters were superior to those of [18F]-FDG PET in prognosticating death and disease progression. PFS and OS were significantly better in patients with lower SUVmax, WBMTV, and WBTLM on [18F]-PFPN PET (log-rank, P < 0.05). In the univariate analyses, distant metastasis, SUVmax, WBMTV, and WBTLM were significantly associated with cumulative incidence of PFS and OS (P < 0.05). In the multivariate analysis, SUVmax was an independent predictor of PFS and OS. CONCLUSIONS: [18F]-PFPN PET has a role in prognostication of melanoma patients. Patients with higher [18F]-PFPN SUVmax have worse prognosis. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT05645484. Registered 9 December, 2022, https://clinicaltrials.gov/ct2/show/NCT05645484?cond=The+Prognostic+Value+of+18F-PFPN+PET+Imaging+in+Patients+With+Malignant+Melanoma&draw=2&rank=1.

Characterizing Early-Onset Alzheimer Disease Using Multiprobe PET/MRI: An AT(N) Framework-Based Study.

PURPOSE: Early-onset Alzheimer disease (EOAD) is rare, highly heterogeneous, and associated with poor prognosis. This AT(N) Framework-based study aimed to compare multiprobe PET/MRI findings between EOAD and late-onset Alzheimer disease (LOAD) patients and explore potential imaging biomarkers for characterizing EOAD. METHODS: Patients with AD who underwent PET/MRI in our PET center were retrospectively reviewed and grouped according to the age at disease onset: EOAD, younger than 60 years; and LOAD, 60 years or older. Clinical characteristics were recorded. All study patients had positive ß-amyloid PET imaging; some patients also underwent 18 F-FDG and 18 F-florzolotau PET. Imaging of the EOAD and LOAD groups was compared using region-of-interest and voxel-based analysis. Correlation of onset age and regional SUV ratios were also evaluated. RESULTS: One hundred thirty-three patients were analyzed (75 EOAD and 58 LOAD patients). Sex ( P = 0.515) and education ( P = 0.412) did not significantly differ between groups. Mini-Mental State Examination score was significantly lower in the EOAD group (14.32 ± 6.74 vs 18.67 ± 7.20, P = 0.004). ß-Amyloid deposition did not significantly differ between groups. Glucose metabolism in the frontal, parietal, precuneus, temporal, occipital lobe, and supramarginal and angular gyri was significantly lower in the EOAD group (n = 49) than in the LOAD group (n = 44). In voxel-based morphometry analysis, right posterior cingulate/precuneus atrophy was more obvious in the EOAD ( P < 0.001), although no voxel survived family-wise error correction. Tau deposition in the precuneus, parietal lobe, and angular, supramarginal, and right middle frontal gyri was significantly higher in the EOAD group (n = 18) than in the LOAD group (n = 13). CONCLUSIONS: Multiprobe PET/MRI showed that tau burden and neuronal damage are more severe in EOAD than in LOAD. Multiprobe PET/MRI may be useful to assess the pathologic characteristics of EOAD.

[177Lu]Lu-PSMA-617 theranostic probe for hepatocellular carcinoma imaging and therapy.

PURPOSE: This study aimed to explore the feasibility of using [177Lu]Lu-prostate-specific membrane antigen (PSMA)-617 and [177Lu]Lu-Evans blue (EB)-PSMA-617 for in vivo radioligand therapy by single-dose administration in a PSMA-positive hepatocellular carcinoma (HCC) xenograft mouse model. METHODS: [177Lu]Lu-PSMA-617 and [177Lu]Lu-EB-PSMA-617 were prepared, and labelling efficiency and radiochemical purity were determined. A HepG2 human HCC subcutaneous xenograft mouse model was established. After intravenous injection of [177Lu]Lu-PSMA-617 or [177Lu]Lu-EB-PSMA-617 (37 MBq) into the mouse model, single-photon emission computed tomography/computed tomography (SPECT/CT) was performed. Biodistribution studies were conducted to verify targeting specificity and pharmacokinetics. In the radioligand therapy study, mice were randomized into 4 groups: 37 MBq [177Lu]Lu-PSMA-617, 18.5 MBq [177Lu]Lu-PSMA-617, 7.4 MBq [177Lu]Lu-EB-PSMA-617, and saline (control). A single-dose administration was applied at the beginning of therapy studies. Tumor volume, body weight, and survival were monitored every 2 days. After the end of therapy, mice were euthanized. Tumors were then weighed, and systemic toxicity was evaluated via blood testing and histological examination of healthy organs. RESULTS: [177Lu]Lu-PSMA-617 and [177Lu]Lu-EB-PSMA-617 were successfully prepared with high purity and stability. SPECT/CT and biodistribution showed that tumor uptake was higher and persisted longer for [177Lu]Lu-EB-PSMA-617 compared with [177Lu]Lu-PSMA-617. [177Lu]Lu-PSMA-617 was rapidly cleared from the blood, while [177Lu]Lu-EB-PSMA-617 persisted for significantly longer. In radioligand therapy studies, tumor growth was significantly suppressed in the 37 MBq [177Lu]Lu-PSMA-617, 18.5 MBq [177Lu]Lu-PSMA-617, and 7.4 MBq [177Lu]Lu-EB-PSMA-617 groups compared to the saline group. Median survival was 40, 44, 43, and 30 days, respectively. No healthy organ toxicity was observed in safety and tolerability evaluation. CONCLUSIONS: Radioligand therapy using [177Lu]Lu-PSMA-617 and [177Lu]Lu-EB-PSMA-617 significantly suppressed tumor growth and prolonged survival time in PSMA-positive HCC xenograft mice without obvious toxicity. These radioligands appear promising for clinical use in humans, and future studies are warranted.

Preparation and In Vitro Evaluation of a Gadolinium-Containing Vitamin E TPGS Micelle as a Potential Contrast Agent for MR Imaging.

The application of many currently evaluated macromolecular contrast agents for magnetic resonance imaging (MRI) has been limited because of their bio-incompatibility and toxicity. The aim of this study is to synthesize and characterize a new micelle-based TPGS gadolinium chelate as a biocompatible MRI contrast agent for prolonged blood circulation time and good tumor imaging contrast. The TPGS-gadolinium conjugate was prepared through the conjugation between TPGS-SA and bifunctional L-NETA-Gd chelate. The conjugate was characterized with regard to molecular weight, critical micellar concentration and particle sizes, cellular uptake, and in vitro cell MRI. Distributions of the MRI contrast agent in various organs were determined via intravenous injection of the agent into mice bearing xenograft tumors. The successfully prepared TPGS-L-NETA-Gd micelle exhibited improved cellular uptake in HepG2 cells and xenografts and high in vivo safety. Distributions of TPGS-L-NETA-Gd in mice showed enhanced cellular uptake up to 2 h after the contrast agent injection. Its in vitro and in vivo properties make it a favorable macromolecular MRI contrast agent for future in vivo imaging.

Q.Clear reconstruction for reducing the scanning time for 68 Ga-DOTA-FAPI-04 PET/MR imaging.

PURPOSE: This study aims to determine whether Q.Clear positron emission tomography (PET) reconstruction may reduce tracer injection dose or shorten scanning time in 68Gallium-labelled fibroblast activation protein inhibitor (68 Ga-FAPI) PET/magnetic resonance (MR) imaging. METHODS: We retrospectively collected cases of 68 Ga-FAPI whole-body imaging performed on integrated PET/MR. PET images were reconstructed using three different methods: ordered subset expectation maximization (OSEM) reconstruction with full scanning time, OSEM reconstruction with half scanning time, and Q.Clear reconstruction with half scanning time. We then measured standardized uptake values (SUVs) within and around lesions, alongside their volumes. We also evaluated image quality using lesion-to-background (L/B) ratio and signal-to-noise ratio (SNR). We then compared these metrics across the three reconstruction techniques using statistical methods. RESULTS: Q.Clear reconstruction significantly increased SUVmax and SUVmean within lesions (more than 30%) and reduced their volumes in comparison with OSEM reconstruction. Background SUVmax also increased significantly, while background SUVmean showed no difference. Average L/B values for Q.Clear reconstruction were only marginally higher than those from OSME reconstruction with half-time. SNR decreased significantly in Q.Clear reconstruction compared with OSEM reconstruction with full time (but not half time). Differences between Q.Clear and OSEM reconstructions in SUVmax and SUVmean values within lesions were significantly correlated with SUVs within lesions. CONCLUSIONS: Q.Clear reconstruction was useful for reducing PET injection dose or scanning time while maintaining the image quality. Q.Clear may affect PET quantification, and it is necessary to establish diagnostic recommendations based on Q.Clear results for Q.Clear application.

Nanomedicine for renal cell carcinoma: imaging, treatment and beyond.

The kidney is a vital organ responsible for maintaining homeostasis in the human body. However, renal cell carcinoma (RCC) is a common malignancy of the urinary system and represents a serious threat to human health. Although the overall survival of RCC has improved substantially with the development of cancer diagnosis and management, there are various reasons for treatment failure. Firstly, without any readily available biomarkers, timely diagnosis has been greatly hampered. Secondly, the imaging appearance also varies greatly, and its early detection often remains difficult. Thirdly, chemotherapy has been validated as unavailable for treating renal cancer in the clinic due to its intrinsic drug resistance. Concomitant with the progress of nanotechnological methods in pharmaceuticals, the management of kidney cancer has undergone a transformation in the recent decade. Nanotechnology has shown many advantages over widely used traditional methods, leading to broad biomedical applications ranging from drug delivery, prevention, diagnosis to treatment. This review focuses on nanotechnologies in RCC management and further discusses their biomedical translation with the aim of identifying the most promising nanomedicines for clinical needs. As our understanding of nanotechnologies continues to grow, more opportunities to improve the management of renal cancer are expected to emerge.

Chlorin e6-loaded goat milk-derived extracellular vesicles for Cerenkov luminescence-induced photodynamic therapy.

PURPOSE: Photodynamic therapy (PDT) is a promising cancer treatment strategy with rapid progress in preclinical and clinical settings. However, the limitations in penetration of external light and precise delivery of photosensitizers hamper its clinical translation. As such, the internal light source such as Cerenkov luminescence (CL) from decaying radioisotopes offers new opportunities. Herein, we show that goat milk-derived extracellular vesicles (GEV) can act as a carrier to deliver photosensitizer Chlorin e6 (Ce6) and tumor-avid 18F-FDG can activate CL-induced PDT for precision cancer theranostics. METHODS: GEV was isolated via differential ultracentrifugation of commercial goat milk and photosensitizer Ce6 was loaded by co-incubation to obtain Ce6@GEV. Tumor uptake of Ce6@GEV was examined using confocal microscopy and flow cytometry. To demonstrate the ability of 18F-FDG to activate photodynamic effects against cancer cells, apoptosis rates were measured using flow cytometry, and the production of 1O2 was measured by reactive oxygen species (ROS) monitoring kit. Moreover, we used the IVIS device to detect Cherenkov radiation and Cerenkov radiation energy transfer (CRET). For animal experiments, a small-animal IVIS imaging system was used to visualize the accumulation of the GEV drug delivery system in tumors. PET/CT and CL images of the tumor site were performed at 0.5, 1, and 2 h. For in vivo antitumor therapy, changes of tumor volume, survival time, and body weight in six groups of tumor-bearing mice were monitored. Furthermore, the blood sample and organs of interest (heart, liver, spleen, lungs, kidneys, and tumor) were collected for hematological analysis, immunohistochemistry, and H&E staining. RESULTS: Confocal microscopy of 4T1 cells incubated with Ce6@GEV for 4 h revealed strong red fluorescence signals in the cytoplasm, which demonstrated that Ce6 loaded in GEV could be efficiently delivered into tumor cells. When Ce6@GEV and 18F-FDG co-existed incubated with 4T1 cells, the cell viability plummeted from more than 88.02 ± 1.30% to 23.79 ± 1.59%, indicating excellent CL-induced PDT effects. In vivo fluorescence images showed a peak tumor/liver ratio of 1.36 ± 0.09 at 24 h after Ce6@GEV injection. For in vivo antitumor therapy, Ce6@GEV + 18F-FDG group had the best tumor inhibition rate (58.02%) compared with the other groups, with the longest survival rate (35 days, 40%). During the whole treatment process, neither blood biochemical analysis nor histological observation revealed vital organ damage, suggesting the biosafety of this treatment strategy. CONCLUSIONS: The simultaneous accumulation of 18F-FDG and Ce6 in tumor tissues is expected to overcome the deficiency of traditional PDT. This strategy has the potential to extend PDT to a variety of tumors, including metastases, using targeted radiotracers to provide internal excitation of light-responsive therapeutics. We expect that our method will play a critical role in precision treatment of deep solid tumors.

A prognostication system based on clinical parameters and [18F]-FDG PET/CT in patients with newly diagnosed multiple myeloma.

PURPOSE: This study aimed to assess prognosis of patients with newly diagnosed multiple myeloma (NDMM) by combining [18F]-FDG positron emission tomography (PET)/CT parameters and clinical indices. METHODS: Clinical data and PET/CT parameters of 133 NDMM patients were retrospectively analyzed for associations between clinical indices and PET/CT parameters. Independent predictors of progression-free survival (PFS) and overall survival (OS) were determined. A new prognostic prediction system (NPPS) was constructed based on our findings. Prediction effectiveness was compared among the NPPS, International Staging System (ISS), Revised ISS (R-ISS), and R2-ISS. RESULTS: Prevalence of elevated ß2-microglobulin, serum creatinine (sCr), serum calcium (sCa), and C-reactive protein concentrations was higher in patients with higher SUVmax (≥ 5.3). Prevalence of elevated sCa, sCr, and extramedullary disease (EMD) was higher in patients with a higher number of focal lesions (≥ 10). SUVmax, serum free-light chain (sFLC) ratio, and EMD were independent predictors of PFS and OS. The NPPS used SUVmax, sFLC ratio, and EMD could effectively predict OS and was more effective at prognostication than the ISS, R-ISS, and R2-ISS. CONCLUSIONS: [18F]-FDG PET/CT parameters play a significant role in predicting prognosis in NDMM patients. The NPPS based on SUVmax, sFLC ratio, and EMD outperformed the ISS, R-ISS, and R2-ISS in prognostication.

68Ga-FAPI PET visualize heart failure: from mechanism to clinic.

PURPOSE: Heart failure (HF) is a chronic progressive clinical syndrome associated with structural and/or functional heart abnormalities. Active fibroblasts and ventricular remodelling play an essential role in HF progression. 68Ga-labelled fibroblast activation protein (FAP) inhibitor (68Ga-FAPI) binds to FAP. This study aimed to examine the feasibility of using 68Ga-FAPI positron emission tomography (PET)/computed tomography (CT) to visualize changes in cardiac fibrosis and function over time in the HF setting. METHODS: After establishing an isoproterenol (ISO)-induced HF rat model (14 consecutive days of intraperitoneal ISO injections), echocardiography and 68Ga-FAPI PET/CT were performed weekly in experimental and control groups. Rat hearts were examined weekly for biodistribution analysis; autoradiography; and haematoxylin and eosin, FAP immunofluorescence and Masson's trichrome staining analysis. Rat blood was sampled weekly for enzyme-linked immunosorbent assay analysis of various plasma indicators. A preliminary clinical study was also performed in seven HF patients who underwent both 13N-amino (NH3) perfusion and 68Ga-FAPI cardiac PET imaging. RESULTS: In the animal experiments, myocardial 68Ga-FAPI uptake, expression of FAP and myocardial contractility peaked on day 7 after the initial ISO injection. Only slight fibrotic changes were observed on histopathological examination. 68Ga-FAPI uptake and ventricular wall motion decreased over time as cardiac fibrosis and degree of myocardial injury gradually increased. In the human HF patient study, 68Ga-FAPI PET imaging identified varying degrees of 68Ga-FAPI uptake in the myocardium that did not precisely match with 13N-NH3 myocardial perfusion. CONCLUSION: As HF progresses, 68Ga-FAPI uptake is high in the early stages and then gradually decreases. Although preliminary, our findings suggest that 68Ga-FAPI PET can be used to demonstrate active myocardial fibrosis. Active myocardial FAP expression is followed by myocardial remodelling and fibrosis. Detection of early active FAP expression may assist treatment decision making in HF patients. CLINICAL TRIAL REGISTRATION: NCT04982458.

An infection-microenvironment-targeted and responsive peptide-drug nanosystem for sepsis emergency by suppressing infection and inflammation.

Sepsis is a life-threatening emergency that causes millions of deaths every year due to severe infection and inflammation. Nevertheless, current therapeutic regimens are inadequate to promptly address the vast diversity of potential pathogens. Omiganan, an antimicrobial peptide, has shown promise for neutralizing endotoxins and eliminating diverse pathogens. However, its clinical application is hindered by safety and stability concerns. Herein, we present a nanoscale drug delivery system (Omi-hyd-Dex@HA NPs) that selectively targets infectious microenvironments (IMEs) and responds to specific stimuli for efficient intervention in sepsis. The system consists of omiganan-dexamethasone conjugates linked by hydrazone bonds which self-assemble into nanoparticles coated with a hyaluronic acid (HA). The HA coating not only facilitates IMEs-targeting through interaction with intercellular-adhesion-molecule-1 on inflamed endotheliocytes, but also improves the biosafety of the nanosystem and enhances drug accumulation in primary infection sites triggered by hyaluronidase. The nanoparticles release dual drugs in IMEs through pH-sensitive cleavage of hydrazone bonds to eradicate pathogens and suppress inflammation. In multiple tissue infection and sepsis animal models, Omi-hyd-Dex@HA NPs exhibited rapid source control and comprehensive inflammation reduction, thereby preventing subsequent fatal complications and significantly improving survival outcomes. The bio-responsive and self-delivering nanosystem offers a promising strategy for systemic sepsis treatment in emergencies.

Development and Evaluation of a Peptide Heterodimeric Tracer Targeting CXCR4 and Integrin αvß3 for Pancreatic Cancer Imaging.

Nowadays, pancreatic cancer is still a formidable disease to diagnose. The CXC chemokine receptor 4 (CXCR4) and integrin αvß3 play important roles in tumor development, progression, invasion, and metastasis, which are overexpressed in many types of human cancers. In this study, we developed a heterodimeric tracer 68Ga-yG5-RGD targeting both CXCR4 and integrin αvß3, and evaluated its feasibility and utility in PET imaging of pancreatic cancer. The 68Ga-yG5-RGD could accumulate in CXCR4/integrin αvß3 positive BxPC3 tumors in a high concentration and was much higher than that of 68Ga-yG5 (p < 0.001) and 68Ga-RGD (p < 0.001). No increased uptake of 68Ga-yG5-RGD was found in MX-1 tumors (CXCR4/integrin αvß3, negative). In addition, the uptake of 68Ga-yG5-RGD in BxPC3 was significantly blocked by excess amounts of AMD3100 (an FDA-approved CXCR4 antagonist) and/or unlabeled RGD (p < 0.001), confirming its dual-receptor targeting properties. The ex vivo biodistribution and immunohistochemical results were consistent with the in vivo imaging results. The dual-receptor targeting strategy achieved improved tumor-targeting efficiency and prolonged tumor retention in BxPC3 tumors, suggesting 68Ga-yG5-RGD is a promising tracer for the noninvasive detection of tumors that express either CXCR4 or integrin αvß3 or both, and therefore may have good prospects for clinical translation.

Visualizing γδ T cells by very late antigen-4-targeted positron emission tomography.

PURPOSE: γδ T cell-based immunotherapy has been rolled out as a promising treatment strategy for malignant tumors due to their potent anti-tumor cytotoxicity, ease of expansion, and unrestricted MHC feature. However, the dynamics and outcomes of γδ T cells in tumor sites are poorly understood. Reported strategies rely on ex vivo biolabeling, significantly limiting the application of γδ T cell molecular imaging. Herein, we investigated whether VLA-4 (very late antigen-4), a crucial component in the effective trafficking of lymphocytes, could serve as a biomarker to non-invasively visualize γδ T cells. METHODS: VLA-4-targeted tracer, 68 Ga-LLP2A, was evaluated in MDA-MB-231- and A549-bearing mice with adoptive transfer of γδ T cells by longitudinal PET/CT imaging. Imaging data were verified by ex vivo biodistribution studies, and the co-localization of CD3 and VLA-4 was validated by immunohistochemistry studies. RESULTS: 68 Ga-LLP2A showed high specificity to VLA-4-expressing γδ T cells in both in vitro and tumor-bearing mice with adoptive transfer of γδ T cells. Longitudinal PET imaging of 68 Ga-LLP2A in tumor-bearing mice with adoptive transfer of γδ T cells showed an increasing tumor tracer uptake, revealing the tumor-specific homing of γδ T cells. The presence of VLA-4-expressing γδ T cells in tumors was confirmed via histological analysis. CONCLUSION: To the best of our knowledge, we reported the first molecular probe, 68 Ga-LLP2A, for in vivo imaging of γδ T cells in live tumors, which advances PET imaging of γδ T cells and supports the translation of imaging agents for immunotherapeutic monitoring.

Evaluation of a CD13 and Integrin αvß3 Dual-Receptor Targeted Tracer 68Ga-NGR-RGD for Ovarian Tumor Imaging: Comparison With 18F-FDG.

Ovarian cancer has the highest mortality rate of gynecologic malignancy. 18F-FDG positron emission tomography (PET) adds an important superiority over traditional anatomic imaging modalities in oncological imaging but has drawbacks including false negative results at the early stage of ovarian cancer, and false positives when inflammatory comorbidities are present. Aminopeptidase N (APN, also known as CD13) and integrin αvß3 are two important targets overexpressed on tumor neo-vessels and frequently on ovarian cancerous cells. In this study, we used subcutaneous and metastatic models of ovarian cancer and muscular inflammation models to identify 68Ga-NGR-RGD, a heterodimeric tracer consisting of NGR and RGD peptides targeting CD13 and integrin αvß3, respectively, and compared it with 18F-FDG. We found that 68Ga-NGR-RGD showed greater contrast in SKOV3 and ES-2 tumors than 18F-FDG. Low accumulation of 68Ga-NGR-RGD but avid uptake of 18F-FDG were observed in inflammatory muscle. In abdominal metastasis models, PET imaging with 68Ga-NGR-RGD allowed for rapid and clear delineation of both peritoneal and liver metastases (3-6 mm), whereas, 18F-FDG could not distinguish the metastasis lesions due to the relatively low metabolic activity in tumors and the interference of intestinal physiological 18F-FDG uptake. Due to the high tumor-targeting efficacy, low inflammatory uptake, and higher tumor-to-background ratios compared to that of 18F-FDG, 68Ga-NGR-RGD presents a promising imaging agent for diagnosis, staging, and follow-up of ovarian tumors.

Gallium-68-labeled fibroblast activation protein inhibitor PET in gastrointestinal cancer: insights into diagnosis and management.

PURPOSE: Gallium-68-labeled fibroblast activation protein inhibitor (68Ga-FAPI) is an emerging promising tumor tracer. This study aims to evaluate the diagnostic efficiency of 68Ga-FAPI PET in gastrointestinal cancer, and to determine its potential impact on clinical management. METHODS: Patients with malignancies were prospectively enrolled in a clinical trial to evaluate the diagnostic value of 68Ga-FAPI PET. One hundred twenty patients with gastrointestinal malignancies (121 68Ga-FAPI PET scans) between June 2020 and May 2021 were retrospectively analyzed. Initial staging of untreated patients and restaging of treated patients were evaluated. The treatment scheme promoted by imaging was determined according to NCCN guidelines. Final diagnosis and treatment reference standards were determined by a dedicated multidisciplinary team. The diagnostic performance and treatment guidance of 68Ga-FAPI PET were compared with those of conventional imaging (CI) and 18F-FDG PET. RESULTS: The diagnostic accuracy of 68Ga-FAPI PET was much higher than that of CI and 18F-FDG PET (95.0% vs. 65.1% and 69.0%, respectively, both p < 0.001). 68Ga-FAPI PET revised diagnosis in 30.3% and 26.2% of patients compared with CI and 18F-FDG PET. The accordance rate of 68Ga-FAPI PET-guided treatment in comparison with the reference standard was significantly higher than that of CI and 18F-FDG PET (96.7% vs. 75.2% and 76.2%, respectively, both p < 0.001). 68Ga-FAPI PET changed treatment in 22.9% and 23.8% of patients compared with CI and 18F-FDG PET. CONCLUSIONS: 68Ga-FAPI PET showed remarkable diagnostic performance in gastrointestinal cancer, resulting in more accurate staging and guidance for timely treatment revision, thereby having a critical impact on clinical management. TRIAL REGISTRATION: NCT04554719. Registered September 8, 2020-retrospectively registered, http://clinicaltrails.gov/show/NCT04554719.