Development of small-molecular-based radiotracers for PET imaging of PD-L1 expression and guiding the PD-L1 therapeutics.

PURPOSE: Programmed cell death protein ligand 1 (PD-L1) is a crucial biomarker for immunotherapy. However, nearly 70% of patients do not respond to PD-L1 immune checkpoint therapy. Accurate monitoring of PD-L1 expression and quantification of target binding during treatment are essential. In this study, a series of small-molecule radiotracers were developed to assess PD-L1 expression and direct immunotherapy. METHODS: Radiotracers of [68Ga]Ga-D-PMED, [68Ga]Ga-D-PEG-PMED, and [68Ga]Ga-D-pep-PMED were designed based on a 2-methyl-3-biphenyl methanol scaffold and successfully synthesized. Cellular experiments and molecular docking assays were performed to determine their specificity for PD-L1. PD-L1 status was investigated via positron emission tomography (PET) imaging in MC38 tumor models. PET imaging of [68Ga]Ga-D-pep-PMED was performed to noninvasively quantify PD-L1 blocking using an anti-mouse PD-L1 antibody (PD-L1 mAb). RESULTS: The radiosyntheses of [68Ga]Ga-D-PMED, [68Ga]Ga-D-PEG-PMED, and [68Ga]Ga-D-pep-PMED were achieved with radiochemical yields of 87 ± 6%, 82 ± 4%, and 79 ± 9%, respectively. In vitro competition assays demonstrated their high affinities (the IC50 values of [68Ga]Ga-D-PMED, [68Ga]Ga-D-PEG-PMED, and [68Ga]Ga-D-pep-PMED were 90.66 ± 1.24, 160.8 ± 1.35, and 51.6 ± 1.32 nM, respectively). At 120 min postinjection (p.i.) of the radiotracers, MC38 tumors displayed optimized tumor-to-muscle ratios for all radioligands. Owing to its hydrophilic modification, [68Ga]Ga-D-pep-PMED had the highest target-to-nontarget (T/NT) ratio of approximately 6.2 ± 1.2. Interestingly, the tumor/liver ratio was hardly affected by different concentrations of the inhibitor BMS202. We then evaluated the impacts of dose and time on accessible PD-L1 levels in the tumor during anti-mouse PD-L1 antibody treatment. The tumor uptake of [68Ga]Ga-D-pep-PMED significantly decreased with increasing PD-L1 mAb dose. Moreover, after 8 days of treatment with a single antibody, the uptake of [68Ga]Ga-D-pep-PMED in the tumor significantly increased but remained lower than that in the saline group. CONCLUSION: PET imaging with [68Ga]Ga-D-pep-PMED, a small-molecule radiotracer, is a promising tool for evaluating PD-L1 expression and quantifying the target blockade of PD-L1 to assist in the development of effective therapeutic regimens.

Synthesis, preclinical, and initial clinical evaluation of integrin αVß3 and gastrin-releasing peptide receptor (GRPR) dual-targeting radiotracer [68Ga]Ga-RGD-RM26-03.

Integrin receptor αvß3 and gastrin-releasing peptide receptor (GRPR) expression of tumors could be detected using PET imaging with radiolabeled Arg-Gly-Asp (RGD) and the antagonistic bombesin analog RM26, respectively. The purpose of this study was to investigate the dual receptor-targeting property of the heterodimer RGD-RM26-03 (denoted as LNC1015), demonstrate the tumor diagnostic value of [68Ga]Ga-LNC1015 in preclinical experiments, and evaluate its preliminary clinical feasibility. METHODS: LNC1015 was designed and synthesized by linking cyclic RGD and the RM26 peptide. Preclinical pharmacokinetics were detected in a PC3 xenograft model using microPET and biodistribution studies. The clinical feasibility of [68Ga]Ga-LNC1015 PET/CT was performed in patients with breast cancer, and the results were compared with those of 18F-fluorodeoxyglucose (FDG). RESULTS: [68Ga]Ga-LNC1015 had good stability in saline for at least 2 h, and favorable binding affinity and specificity were demonstrated in vitro and in vivo. The tumor uptake and retention of [68Ga]Ga-LNC1015 during PET imaging were improved compared with its monomeric counterparts [68Ga]Ga-RGD and [68Ga]Ga-RM26 at all the time points examined. In our initial clinical studies, the tumor uptake and tumor-to-background ratio (TBR) of primary and metastatic lesions in [68Ga]Ga-LNC1015 PET/CT were significantly higher than those in [18F]FDG PET/CT, resulting in high lesion detection rate and tumor delineation. CONCLUSION: The dual targeting radiotracer [68Ga]Ga-LNC1015 showed significantly improved tumor uptake and retention, as well as lower liver uptake than [68Ga]Ga-RGD and [68Ga]Ga-RM26 monomer. The first-in-human study showed high TBRs in patients, suggesting favorable pharmacokinetics and high clinical feasibility for PET/CT imaging of cancer.

Development of STING probes and visualization of STING in multiple tumor types.

PURPOSE: The stimulator of interferon genes (STING) is a critical component of the innate immune system and plays a pivotal role in tumor immunotherapy. Developing non-invasive in vivo diagnostic methods for visualizing STING is highly valuable for STING-related immunotherapy. This work aimed to build a noninvasive imaging platform that can dynamically and quantitatively monitor tumor STING expression. METHODS: We investigated the in vivo positron emission tomography (PET) imaging of STING-expressing tumors (B16F10, MC38, and Panc02) with STING-targeted radioprobe ([18F]F-CRI1). The expression of STING in tumors was quantified, and correlation analysis was performed between these results and the outcomes of PET imaging. Furthermore, we optimized the structure of [18F]F-CRIn with polyethylene glycol (PEG) to improve the pharmacokinetic characteristics in vivo. A comprehensive comparison of the imaging and biodistribution results obtained with the optimized probes was conducted in the B16F10 tumors. RESULTS: The PET imaging results showed that the uptake of [18F]F-CRI1 in tumors was positively correlated with the expression of STING in tumors (r = 0.9184, P < 0.001 at 0.5 h). The lipophilicity of the optimized probes was significantly reduced. As a result of employing optimized probes, B16F10 tumor-bearing mice exhibited significantly improved tumor visualization in PET imaging, along with a marked reduction in retention within non-target areas such as the gallbladder and intestines. Biodistribution experiments further validated the efficacy of probe optimization in reducing uptake in non-target areas. CONCLUSION: In summary, this work demonstrated a promising pathway for the development of STING-targeted radioprobes, advancing in vivo PET imaging capabilities.

Development and Evaluation of [68Ga]Ga-Labeled Riboflavin Derivative for RFVT3-Targeted PET Imaging of Melanoma in Mice.

The limited progress in treatment options and the alarming survival rates in advanced melanoma emphasize the significant research importance of early melanoma diagnosis. RFVT3, a crucial protein at the core of energy metabolism reprogramming in melanoma, might play a pivotal role in early detection. In this study, [68Ga]Ga-NOTA-RF, based on riboflavin (RF), was rationally developed and validated, serving as an innovative tool for positron emission tomography (PET) imaging of RFVT3 expression in melanoma. The in vitro assays of RFVT3 specificity of [68Ga]Ga-NOTA-RF were performed on B16F10 melanoma cells. Then, PET imaging of melanoma was investigated in B16F10 allograft mouse models with varying volumes. Biodistribution studies are used to clarify the behavior of [68Ga]Ga-NOTA-RF in vivo. [68Ga]Ga-NOTA-RF was obtained with high radiochemical purity (>95%). A significant uptake (37.79 ± 6.86%, n = 4) of [68Ga]Ga-NOTA-RF was observed over time in B16F10 melanoma cells, which was significantly inhibited by RFVT3 inhibitors RF or methylene blue (MB), demonstrating the specific binding of [68Ga]Ga-NOTA-RF. At 60 min postinjection, the tumor-to-muscle (T/M) ratio of [68Ga]Ga-NOTA-RF was 4.03 ± 0.34, higher than that of the RF-blocked group (2.63 ± 0.19) and MB-blocked group (2.14 ± 0.20). The T/M ratios for three distinct tumor volumes-small (5 mm), medium (10 mm), and large (15 mm) were observed to be 5.25 ± 0.28, 4.03 ± 0.34, and 3.19 ± 0.55, respectively. The expression of RFVT3 was validated by immunohistochemical staining in various tumor models, with small B16F10 tumors exhibiting the highest expression. [68Ga]Ga-NOTA-RF demonstrates promising properties for the early diagnosis of melanoma and the examination of minute metastatic lesions, indicating its potential to assist in guiding clinical treatment decisions.

Development and Evaluation of DOTA-FAPI-Maleimide as a Novel Radiotracer for Tumor Theranostic with Extended Circulation.

This study aimed to evaluate a novel albumin-binding strategy for addressing the challenge of insufficient tumor retention of fibroblast activation protein inhibitors (FAPIs). Maleimide, a molecule capable of covalent binding to free thiol groups, was modified to conjugate with FAPI-04 in order to enhance its binding to endogenous albumin, resulting in an extended blood circulation half-life and increased tumor uptake. DOTA-FAPI-maleimide was prepared and radiolabeled with Ga-68 and Lu-177, followed by cellular assays, pharmacokinetic analysis, PET/CT, and SPECT/CT imaging to assess the probe distribution in various tumor-bearing models. Radiolabeling of the modified probe was successfully achieved with a radiochemical yield of over 99% and remained stable for 144 h. Cellular assays showed that the ligand concentration required for 50% inhibition of the probe was 1.20 ± 0.31 nM, and the Kd was 0.70 ± 0.07 nM with a Bmax of 7.94 ± 0.16 fmol/cell, indicative of higher specificity and affinity of DOTA-FAPI-maleimide compared to other FAPI-04 variants. In addition, DOTA-FAPI-maleimide exhibited a persistent blood clearance half-life of 7.11 ± 0.34 h. PET/CT images showed a tumor uptake of 2.20 ± 0.44%ID/g at 0.5 h p.i., with a tumor/muscle ratio of 5.64 in HT-1080-FAP tumor-bearing models. SPECT/CT images demonstrated long-lasting tumor retention. At 24 h p.i., the tumor uptake of [177Lu]Lu-DOTA-FAPI-maleimide reached 5.04 ± 1.67%ID/g, with stable tumor retention of 3.40 ± 1.95%ID/g after 4 days p.i. In conclusion, we developed and evaluated the thiol group-attaching strategy, which significantly extended the circulation and tumor retention of the adapted FAPI tracer. We envision its potential application for clinical cancer theranostics.

Alcohol Advertising Exposure and Drinking Habits Among Chinese Adolescents in 2021: A National Survey.

Objectives. To assess the exposure of Chinese adolescents to proalcohol advertising and explore its association with alcohol consumption. Methods. A nationally and regionally representative school-based survey was conducted in mainland China in 2021 among students in grades 7 through 12, aged 13 to 18 years. We assessed adolescent exposure to proalcohol advertising and its association with alcohol consumption. Results. A total of 57 336 students participated in the survey, and the exposure percentage of proalcohol advertising was 66.8%, with no difference between boys and girls or between urban and rural areas. The top 3 exposure channels were television (51.8%), the Internet (43.6%), and outdoor billboards (42.0%). The exposure was higher among students who had consumed alcohol in the past 30 days (80.1% vs 65.1%; adjusted odds ratio [AOR] = 1.29) and in the past 12 months (77.3% vs 61.7%; AOR = 1.30). However, no significant correlation was observed between advertising exposure and drunkenness. Conclusions. Approximately two thirds of Chinese adolescents have been exposed to proalcohol advertising in the past 30 days, with television, the Internet, and outdoor billboards being the most prevalent channels. Exposure to proalcohol advertising exhibits a positive correlation with drinking. (Am J Public Health. 2024;114(8):814-823. https://doi.org/10.2105/AJPH.2024.307680).

A proof-of-concept study on bioorthogonal-based pretargeting and signal amplify radiotheranostic strategy.

BACKGROUND: Radiotheranostics differs from the vast majority of other cancer therapies in its capacity for simultaneous imaging and therapy, and it is becoming more widely implemented. A balance between diagnostic and treatment requirements is essential for achieving effective radiotheranostics. Herein, we propose a proof-of-concept strategy aiming to address the profound differences in the specific requirements of the diagnosis and treatment of radiotheranostics. RESULTS: To validate the concept, we designed an s-tetrazine (Tz) conjugated prostate-specific membrane antigen (PSMA) ligand (DOTA-PSMA-Tz) for 68Ga or 177Lu radiolabeling and tumor radiotheranostics, a trans-cyclooctene (TCO) modified Pd@Au nanoplates (Pd@Au-PEG-TCO) for signal amplification, respectively. We then demonstrated this radiotheranostic strategy in the tumor-bearing mice with the following three-step procedures: (1) i.v. injection of the [68Ga]Ga-PSMA-Tz for diagnosis; (2) i.v. injection of the signal amplification module Pd@Au-PEG-TCO; (3) i.v. injection of the [177Lu]Lu-PSMA-Tz for therapy. Firstly, this strategy was demonstrated in 22Rv1 tumor-bearing mice via positron emission tomography (PET) imaging with [68Ga]Ga-PSMA-Tz. We observed significantly higher tumor uptake (11.5 ± 0.8%ID/g) with the injection of Pd@Au-PEG-TCO than with the injection [68Ga]Ga-PSMA-Tz alone (5.5 ± 0.9%ID/g). Furthermore, we validated this strategy through biodistribution studies of [177Lu]Lu-PSMA-Tz, with the injection of the signal amplification module, approximately five-fold higher tumor uptake of [177Lu]Lu-PSMA-Tz (24.33 ± 2.53% ID/g) was obtained when compared to [177Lu]Lu-PSMA-Tz alone (5.19 ± 0.26%ID/g) at 48 h post-injection. CONCLUSION: In summary, the proposed strategy has the potential to expand the toolbox of pretargeted radiotherapy in the field of theranostics.

Progressive Optimization of Lanthanide Nanoparticle Scintillators for Enhanced Triple-Activated Radioluminescence Imaging.

Lanthanide nanoparticle (LnNP) scintillators exhibit huge potential in achieving radionuclide-activated luminescence (radioluminescence, RL). However, their structure-activity relationship remains largely unexplored. Herein, progressive optimization of LnNP scintillators is presented to unveil their structure-dependent RL property and enhance their RL output efficiency. Benefiting from the favorable host matrix and the luminescence-protective effect of core-shell engineering, NaGdF4 : 15 %Eu@NaLuF4 nanoparticle scintillators with tailored structures emerged as the top candidates. Living imaging experiments based on optimal LnNP scintillators validated the feasibility of laser-free continuous RL activated by clinical radiopharmaceuticals for tumor multiplex visualization. This research provides unprecedented insights into the rational design of LnNP scintillators, which would enable efficient energy conversion from Cerenkov luminescence, γ-radiation, and ß-electrons into visible photon signals, thus establishing a robust nanotechnology-aided approach for tumor-directed radio-phototheranostics.

In Vivo Comparative Study of Radioiodinated Folate Receptor Targeting Albumin Probes for Atherosclerosis Plaque Imaging.

The objective of this study is to compare a series of albumin-based folate radiotracers for the potential imaging of folate receptor (FR) positive macrophages in advanced atherosclerotic plaques. Diversified radioiodinated FR-targeting albumin-binding probes ([131I]IBAbHF, [131I]IBNHF, and [131I]HF) were developed through various strategies. Among the three radiotracers, [131I]IBAbHF and [131I]IBNHF showed excellent in vitro stability (>98%) in saline and PBS 7.4 for 24 h. Also, good stability of [131I]IBNHF in mouse serum albumin was monitored using an HSA ELISA kit. The experiments in Raw264.7 macrophages activated by ox-LDL confirmed the specificity of tracers for FR-ß. Biodistribution studies of radiotracers were performed to verify the prolonged blood half-life. Prolonged blood half-lives of [131I]IBAbHF, [131I]HF, and [131I]IBNHF were 17.26 ± 4.29, 6.33 ± 2.64, and 5.50 ± 1.26 h, respectively. SPECT-CT imaging of ApoE-/- mice at different stages was performed to evaluate the progression and monitor the prognosis of AS. Evident [131I]IBNHF uptake in atherosclerotic lesions could be observed along with a low background signal. In summary, we demonstrated a proof-of-concept of albumin-based radioligands for FR-targeting atherosclerosis imaging and found that different incorporation of radioiodinated groups resulted in different pharmacokinetic properties. Among these candidate compounds, [131I]IBNHF would be a satisfactory radiotracer for SPECT imaging of atherosclerosis.

Development of [177Lu]Lu-LNC1003 for radioligand therapy of prostate cancer with a moderate level of PSMA expression.

PURPOSE: Evans blue as an albumin binder has been widely used to improve pharmacokinetics and enhance tumor uptake of radioligands, including prostate-specific membrane antigen (PSMA) targeting agents. The goal of this study is to develop an optimal Evans blue-modified radiotherapeutic agent that could maximize the absolute tumor uptake and tumor absorbed dose thus the therapeutic efficacy to allow treatment of tumors even with moderate level of PSMA expression. METHODS: [177Lu]Lu-LNC1003 was synthesized based on PSMA-targeting agent and Evans blue. Binding affinity and PSMA targeting specificity were verified through cell uptake and competition binding assay in 22Rv1 tumor model that has moderate level of PSMA expression. SPECT/CT imaging and biodistribution studies in 22Rv1 tumor-bearing mice were performed to evaluate the preclinical pharmacokinetics. Radioligand therapy studies were conducted to systematically assess the therapeutic effect of [177Lu]Lu-LNC1003. RESULTS: LNC1003 showed high binding affinity (IC50 = 10.77 nM) to PSMA in vitro, which was comparable with that of PSMA-617 (IC50 = 27.49 nM) and EB-PSMA-617 (IC50 = 7.91 nM). SPECT imaging of [177Lu]Lu-LNC1003 demonstrated significantly improved tumor uptake and retention as compared with [177Lu]Lu-EB-PSMA and [177Lu]Lu-PSMA-617, making it suitable for prostate cancer therapy. Biodistribution studies further confirmed the remarkably higher tumor uptake of [177Lu]Lu-LNC1003 (138.87 ± 26.53%ID/g) over [177Lu]Lu-EB-PSMA-617 (29.89 ± 8.86%ID/g) and [177Lu]Lu-PSMA-617 (4.28 ± 0.25%ID/g) at 24 h post-injection. Targeted radioligand therapy results showed noteworthy inhibition of 22Rv1 tumor growth after administration of a single dose of 18.5 MBq [177Lu]Lu-LNC1003. There was no obvious antitumor effect after [177Lu]Lu-PSMA-617 treatment under the same condition. CONCLUSION: In this study, [177Lu]Lu-LNC1003 was successfully synthesized with high radiochemical purity and stability. High binding affinity and PSMA targeting specificity were identified in vitro and in vivo. With greatly enhanced tumor uptake and retention, [177Lu]Lu-LNC1003 has the potential to improve therapeutic efficacy using significantly lower dosages and less cycles of 177Lu that promises clinical translation to treat prostate cancer with various levels of PSMA expression.

Longitudinal MicroSPECT Imaging of Systemic Sclerosis Model Mice with [99mTc]Tc-HYNFA via Folate Receptor Targeting.

Noninvasive single-photon emission computed tomography (SPECT) imaging with [99mTc]Tc-HYNFA via folate receptor (FR) targeting was proposed to assess the inflammation and therapeutic effect of systemic sclerosis (SSc) in model mice. The radiochemical yield and purity of [99mTc]Tc-HYNFA were over 95%, with a specific activity of about 9.36 ± 0.17 MBq/nmol. At the end of induction, the uptake ratios of bleomycin-injected regions on the back-to-muscle (R/M) and lung-to-muscle (L/M) derived from SPECT images were 7.27 ± 0.50 and 4.25 ± 0.15, respectively. The radioactivity uptakes could be blocked by excessive folic acid (FA), and R/M and L/M obviously decreased to 2.78 ± 0.57 and 2.51 ± 0.79, respectively. R/M (2.22 ± 0.71) and L/M (1.62 ± 0.28) decreased very close to those of the control mice group (R/M = 1.99 ± 0.36, L/M = 1.50 ± 0.14) when macrophages had been depleted in advance. After being treated with cyclophosphamide (CTX) or methotrexate (MTX), R/M and L/M decreased to 3.58 ± 0.52 and 2.03 ± 0.32 (CTX treatment) or 2.48 ± 0.64 and 1.83 ± 0.06 (MTX treatment). R/M and L/M were highly correlated with pathological changes. The trend of hydroxyproline content in lungs at the later non-inflammatory phase of each group was similar to the uptake values of the lung in the 4th week from the beginning of induction. [99mTc]Tc-HYNFA had an ideal uptake in SSc lesions. R/M and L/M had a high consistency with pathological changes. SPECT imaging-targeted FR could monitor the therapeutic effect of CTX and MTX. It is expected to be an effective means to evaluate SSc.

Synthesis and Preclinical Evaluation of a 68Ga-Labeled Pyridine-Based Benzamide Dimer for Malignant Melanoma Imaging.

Benzamide (BZA), a small molecule that can freely cross cell membranes and bind to melanin, has served as an effective targeting group for melanoma theranostics. In this study, a novel pyridine-based BZA dimer (denoted as H-2) was labeled with 68Ga ([68Ga]Ga-H-2) for positron emission tomography (PET) imaging of malignant melanomas. [68Ga]Ga-H-2 was obtained with high radiochemical yield (98.0 ± 2.0%) and satisfactory radiochemical purity (>95.0%). The specificity and affinity of [68Ga]Ga-H-2 were confirmed in melanoma B16F10 cells and in vivo PET imaging of multiple tumor models (B16F10 tumors, A375 melanoma, and lung metastases). Monomeric [68Ga]Ga-H-1 was prepared as a control radiotracer to verify the effects of the molecular structure on pharmacokinetics. The values of the lipid-water partition coefficient of [68Ga]Ga-H-2 and [68Ga]Ga-H-1 demonstrated hydrophilicity with log P = -2.37 ± 0.07 and -2.02 ± 0.09, respectively. PET imaging and biodistribution showed a higher uptake of [68Ga]Ga-H-2 in B16F10 primary and metastatic melanomas than that in A375 melanomas. However, the relatively low uptake of monomeric [68Ga]Ga-H-1 in B16F10 tumors and high accumulation in nontarget organs resulted in poor PET imaging quality. This study demonstrates the synthesis and preclinical evaluation of the novel pyridine-based BZA dimer [68Ga]Ga-H-2 and indicates that the dimer tracer has promising applications in malignant melanoma-specific PET imaging because of its high uptake and long-time retention in malignant melanoma.

Synergism of 64Cu-Labeled RGD with Anti-PD-L1 Immunotherapy for the Long-Acting Antitumor Effect.

We put forward a novel targeting-triggering-therapy (TTT) scheme that combines 64Cu-based targeted radionuclide therapy (TRT) with programmed death-ligand 1 (PD-L1)-based immunotherapy for enhancing therapeutic efficacy. The αvß3 integrin-targeted 64Cu-DOTA-EB-cRGDfK (64Cu-DER) was synthesized. Flow cytometry, immunofluorescence staining, and RT-qPCR were performed to verify PD-L1 upregulation after irradiation with 64Cu-DER. Positron emission tomography imaging was performed to investigate the prominent tumor retention property of 64Cu-DER. In the MC38 tumor model, anti-PD-L1 antibody (αPD-L1 mAb) was delivered in a concurrent or sequential manner after 64Cu-DER was injected, followed by the testing of changes in tumor microenvironment (TME). PD-L1 was upregulated in a time- and dose-dependent manner after being induced by 64Cu-DER. The combination of 64Cu-DER TRT (925 MBq/kg) and αPD-L1 mAb (10 mg/kg) resulted in significant delay in tumor growth and protected against tumor rechallenge. Blockade of PD-L1 at 4 h after 64Cu-DER TRT (64Cu-DER + αPD-L1 mAb @ 4 h combination group) was able to achieve 100% survival rate, prevent tumor relapse, and evidently prolong the survival of mice. In summary, the combination of 64Cu-DER and αPD-L1 mAb in a time-dependent manner could be a promising approach to improve therapeutic efficacy. Understandably, this strategy has the potential to extend the scope of 64Cu-based TTT and merits translation into clinical practice for the better management of immune checkpoint blockade immunotherapy.

A radioiodinated FR-ß-targeted tracer with improved pharmacokinetics through modification with an albumin binder for imaging of macrophages in AS and NAFL.

PURPOSE: The formation of advanced plaques, which is characterized by the uninterrupted aggregation of macrophages with high expression of folate receptor-ß (FR-ß), is observed in several concomitant metabolic syndromes. The objective of this study was to develop a novel FR-ß-targeted single-photon emission computed tomography (SPECT) radiotracer and validate its application to the noninvasive detection of atherosclerosis (AS) plaque and non-alcoholic fatty liver (NAFL). METHODS: Two radioiodinated probes, [131I]IPBF and [131I]IBF, were developed, and cell uptake studies were used to identify their specific targets for activated macrophages. Biodistribution in normal mice was performed to obtain the pharmacokinetic information of the probes. Apolipoprotein E knockout (ApoE-/-) mice with atherosclerotic aortas were induced by a high-fat and high-cholesterol (HFHC) diet. To investigate the affinity of radiotracers to FR-ß, Kd values were determined using in vitro assays. In addition, the assessments of the aorta in the ApoE-/- mice at different stages were performed using in vivo SPECT/CT imaging, and the findings were compared by histology. RESULTS: Both [131I]IPBF and [131I]IBF were synthesized with > 95% radiochemical purity and up to 3 MBq/nmol molar activity. In vitro assay of [131I]IPBF showed a moderate binding affinity to plasma proteins and specific uptake in activated macrophages. The prolonged blood elimination half-life (t1/2z) of [131I]IPBF (8.14 h) was observed in a pharmacokinetic study of normal mice, which was significantly longer than that of [131I]IBF (t1/2z = 2.95 h). As expected, the Kd values of [131I]IPBF and [131I]IBF in the Raw 264.7 cells were 43.94 ± 9.83 nM and 61.69 ± 15.19 nM, respectively. SPECT imaging with [131I]IPBF showed a high uptake in advanced plaques and NAFL. Radioactivity in excised aortas examined by ex vivo autoradiography further confirmed the specific uptake of [131I]IPBF in high-risk AS plaques. CONCLUSIONS: In summary, we reported a proof-of-concept study of an albumin-binding folate derivative for macrophage imaging. The FR-ß-targeted probe, [131I]IPBF, significantly prolongs the plasma elimination half-life and has the potential for the monitoring of AS plaques and concomitant fatty liver.

PD-L1-Targeted Radionuclide Therapy Combined with αPD-L1 Antibody Immunotherapy Synergistically Improves the Antitumor Effect.

Immune checkpoint blockers (ICBs) targeting programmed death receptor 1 (PD-1) ligand 1 (PD-L1) for immunotherapy have radically reformed oncology. It is of great significance to enhance the response rate of ICB in cancer patients. Here, a radioiodinated anti-PD-L1 antibody (131I-αPD-L1) was developed for PD-L1-targeted single-photon emission computed tomography (SPECT) imaging and αPD-L1 immunotherapy. Flow cytometry and immunofluorescence staining were performed to identify PD-L1 upregulation in a time- and dose-dependent manner after being induced by 131I-αPD-L1. ImmunoSPECT imaging and biodistributions of 131I-αPD-L1 in CT26, MC38, 4T1, and B16F10 tumor models were conducted to visualize the high tumor uptake and low background signal. Compared to monotherapy alone, concurrent administration of αPD-L1 mAb and 131I-αPD-L1 revealed improved tumor control in murine tumor models. The combination of 11.1 MBq of 131I-αPD-L1 and 200 µg of αPD-L1 mAb resulted in significant tumor growth delay and prolonged survival. This radioligand synergized immunotherapy strategy holds great potential for cancer management.

Health transition of the causes of mortality between 2005 and 2015 in Guangdong, China.

OBJECTIVES: To analyse the patterns of transition of health burden for 110 causes of death by stratification of age, sex and geographic regions in Guangdong between 2005 and 2015. METHODS: We analysed the age-specific, sex-specific, region-specific mortality in Guangdong based on assembled databases. County-level surveillance data were calculated to inform city-level changes. RESULTS: The age-standardised mortality of all causes, non-communicable diseases (NCDs), communicable diseases, maternal diseases, neonatal diseases, malnutrition and injury declined progressively. Despite declining mortality of NCDs, the overall burden of disease was dominated by NCDs (ie, cerebrovascular disease, chronic obstructive pulmonary disease) that still accounted for 86.93% and 88.12% of death in 2005 and 2015, respectively. Considerable variations across geographic regions were observed (lowest in Pearl River Delta and highest in west Guangdong). There was a modest shift to transport injuries at younger ages and unintentional injuries in the elderly. CONCLUSIONS: We have documented a dramatic change in the overall mortality and age-specific, sex-specific and cause-specific mortality in Guangdong province between 2005 and 2015. The significant burden of NCDs remains a major healthcare issue despite the notable progress in reducing mortality in Guangdong, China. Our findings highlight important unmet needs to refine healthcare services by taking into account the inequity of age, sex and geographic regions. Identification of the 'treatable' risk factors and improved disease surveillance should be continuously improved to minimised the overall and cause-specific mortality.

Radioiodinated 4-(p-Iodophenyl) Butanoic Acid-Modified Estradiol Derivative for ER Targeting SPECT Imaging.

Overexpression of estrogen receptors (ERs) is one of the important characteristics of most breast cancers. We aim to develop a new type of ER-specific radioiodine-labeled estrogen derivative ([131I]IPBA-EE), which was modified with an albumin-specific ligand 4-(p-iodophenyl) butyric acid (IPBA) to improve the metabolic stability and enhance the ER-targeting ability of estrogen. [131I]IPBA-EE can effectively bind to albumin in vitro, and its dissociation constant (Kd = 0.31 µM) is similar to IPBA (Kd = 0.30 µM). The uptake of [131I]IPBA-EE in ER-positive MCF-7 cells (41.81 ± 3.41%) was significantly higher than that in ER-negative MDA-MB-231 cells (8.78 ± 2.37%, ***P < 0.0005) and could be significantly blocked (3.92 ± 0.35%, ***P < 0.0005). The uptakes of [131I]IPBA-EE in rat uterus and ovaries were 5.66 ± 0.34% ID/g and 5.71 ± 2.77% ID/g, respectively, at 1 h p.i., and these uptakes could be blocked by estradiol (uterus: 2.81 ± 0.41% ID/g, *P < 0.05; ovarian: 3.02 ± 0.08% ID/g, *P < 0.05). SPECT/CT imaging showed that ER-positive MCF-7 tumor uptake of [131I]IPBA-EE reached to 6.07 ± 0.20% ID/g at 7 h p.i., which was significantly higher than that of ER-negative MDA-MB-231 tumor (0.87 ± 0.08% ID/g, **P < 0.005) and could be blocked obviously with fulvestrant (1.65 ± 1.56% ID/g, *P < 0.05). In conclusion, a novel radioiodinated estradiol derivative, [131I]IPBA-EE with albumin-binding property and good metabolic stability, was developed to image the ER in breast cancer. This promising ER-targeted probe has the potential to warrant further preclinical investigations.

Estimating causes of out-of-hospital deaths in China: application of SmartVA methods.

BACKGROUND: Most deaths in China occur at home, making it difficult to collect reliable cause of death (CoD) information. Verbal autopsy (VA) was applied using the SmartVA tool to a sample of home deaths in China to explore its feasibility as a means of improving the quality of CoD data. METHODS: The study was carried out in 22 districts in 9 provinces, located in north-east, central, and western areas of China during 2017 and 2018. Trained interviewers selected suitable respondents in each household to collect information using the Population Health Metrics Research Consortium (PHMRC) shortened and validated electronic VA questionnaire on tablets. The CoD was diagnosed from the interview data using the SmartVA-Analyze 2.0 software (Tariff 2.0). RESULTS: Non-communicable diseases (NCDs) dominated the leading causes of death in all age groups and for both sexes. After redistribution of undetermined causes, stroke (24%), ischemic heart diseases (IHD) (21%), chronic respiratory diseases (11%), and lung cancer (6%) were the leading causes of death. The cause fractions for level-one cause categories and ranking of specific causes were similar between SmartVA and results from the Global Burden of Disease (GBD) study. CONCLUSION: Evidence from this large pilot study suggests that SmartVA is a feasible and plausible tool and could be a valuable tool to improve the quality and standardization of CoD information across China.

The burden of oral cancer in China, 1990-2017: an analysis for the Global Burden of Disease, Injuries, and Risk Factors Study 2017.

BACKGROUND: Oral cancer is among the most common malignant tumors worldwide, and it has become an increasingly important public health problem in China. This study systematically assesses the current state of oral cancer in China from 1990 to 2017, providing new information and perspectives for oral health researchers and public health policy makers. METHODS: Based on the Global Burden of Disease, Injuries, and Risk Factors Study 2017 (GBD 2017), we evaluated the incidence rates, mortality and disability-adjusted life year (DALY) rates for oral cancer in China and their changing trends between 1990 and 2017, making comparisons by gender and age. We also assessed the DALY rates associated with oral cancer at the provincial level for 33 provinces and their trends over time. RESULTS: From 1990 to 2017, the number of new cases and the age-standardized incidence rate for oral cancer in China increased by 280.0% and 79.7%, respectively; the number of deaths and the age-standardized mortality rose by 196.8% and 29.0%, respectively; and the number of DALYs and the age-standardized DALY rate increased by 149.1% and 21.0%, respectively. The incidence rates for oral cancer rose after 30 years of age and peaked at 65-69 years; the mortality for oral cancer rose after 50 years of age and peaked at 65-69 years; and the DALY rates for oral cancer rose after 45 years of age and peaked at 65-69 years. The incidence rates, mortality and DALY rates for oral cancer in males were significantly higher than those in females and showed an upward trend, while there was a decrease or no significant change in females. The DALY rates increased in 21 provinces and decreased in 12 provinces, with the largest growth in Henan Province and the largest decline in Hong Kong Province. CONCLUSIONS: The burden of oral cancer in China continues to increase continuously. More prevention, control and intervention measures should be taken and increased attention paid to common risk factors is essential for the prevention of oral cancer.

[Burden of nutritional deficiencies of children under 5 years old in China, 1990-2015].

OBJECTIVE: To quantify and describe the distribution and trends of burden of nutritional deficiencies among children under 5 years old in China from 1990 to 2015. METHODS: Subnational data of China on children under 5 years old in 33 provinces and autonomous regions, which including 31 mainland regions, Hong Kong and Macao Special Administrative Regions, were extracted from the result of Global Burden of Disease Study 2015(GBD 2015). Based on the method of descriptive epidemiology, we analyzed the prevalence, mortality as well as disability adjusted life year(DALY) rate of nutritional deficiencies among children under 5 years old by sex, time and locations in China, as well as its temporal trend since 1990. RESULTS: In 2015, the prevalence of nutritional deficiencies among children under 5 years old was 17. 26%, and the DALY rate was 776. 26 person-years per 100000. Compared to 1990, the DALY rate of nutritional deficiencies declined by 71. 42%. The DALY rate of nutritional deficiencies decreased in the past 25 years in Eastern, Central and Western China. Meanwhile, the gap in disease burden between boys and girls declined. Among diseases caused by nutritional deficiencies, burden of protein-energy malnutrition and iron deficiency anemia among children under 5 years old were relatively higher. Compared to 1990, the DALY rate of iron deficiency anemia among children under 5 years old declined by 15. 68%, which was lower than other nutritional deficiencies among children in 2015. CONCLUSION: From 1990 to 2015, the disease burden caused by nutritional deficiencies among Chinese children under 5 years old showed downtrend. There were still differences of disease burden distributions between regions and common nutritional deficiencies.