Head to head comparison of 68Ga-DOTA-FAPI-04 vs 18F-FDG PET/CT in the evaluation of primary extrapulmonary tumors in the chest.

OBJECTIVE: We conducted a prospective study using 18F-flurodeoxyglucose (18F-FDG) and 68Ga-DOTA-FAPI-04 (fibroblast-activation protein inhibitor, 68Ga-FAPI) PET/CT to diagnose, differentiate, and stage primary extrapulmonary tumors of the thorax. METHODS: Fifty-four participants were undergoing 18F-FDG and 68Ga-FAPI PET/CT and divided into the benign, intermediate, and malignant based on pathology. The maximum standardized uptake value (SUVmax), the tumor-to-blood pool ratio, and tumor-to-liver ratio were compared for primary tumors, lymph nodes, and metastases between the two modalities by two independent samples t tests. One-way ANOVA was used to compare the uptake of 18F-FDG or 68Ga-FAPI among the three groups. RESULTS: Fifty-four participants were confirmed to have 71 primary lesions, 56 metastatic lymph nodes, and 43 metastatic lesions. 18F-FDG PET/CT could both effectively distinguish malignant lesions from non-malignant lesions, accuracies of 87.32% (p < 0.001). 68Ga-FAPI PET/CT effectively differentiated benign lesions from the non-benign, accuracy being 91.55% (p < 0.001). The accuracies of 18F-FDG and 68Ga-FAPI for detecting lymph node metastasis were 77.22% (61/79) and 87.34% (69/79) (p = 0.096). The uptake of 68Ga-FAPI in metastatic lymph nodes was significantly higher than that of the nonmetastatic (p < 0.001). The detection rate of 68Ga-FAPI PET/CT for metastatic lesions was significantly higher than that of 18F-FDG, 100% (43/43) vs. 53.49% (23/43) (p < 0.001). Compared with 18F-FDG PET/CT, 68Ga-FAPI PET/CT changed the treatment strategy of 7.4% (4/54) participants. CONCLUSION: 68Ga-FAPI PET/CT is valuable in the diagnosis and differentiation of primary extrapulmonary tumors and superior to 18F-FDG PET/CT for evaluating lymph node and distant metastasis. CLINICAL RELEVANCE STATEMENT: The application of 68Ga-FAPI PET/CT in primary extrapulmonary chest tumors is valuable, which is reflected in diagnosis, differentiation and exploration of lymph node metastasis and distant metastasis. KEY POINTS: • 68Ga-FAPI PET/CT is valuable in the diagnosis, differentiation, and staging of primary extrapulmonary tumors. • 68Ga-FAPI PET/CT is superior to 18 F-FDG PET/CT for evaluating lymph node and distant metastasis.

Sodium valproate inhibited apoptosis in lethally scalded rat cardiomyocytes by regulating hypoxia-inducible factor-1α expression.

This study assessed the inhibitory effect of sodium valproate (VPA) on apoptosis of cardiomyocytes in lethally scalded rats. The model of a 50% total body surface area (TBSA) third-degree full-thickness scald was produced, 48 male SD rats were randomly divided into three groups (n = 16), the sham group and the scald group were given an intraperitoneal injection of 0.25ml of saline, the scald +VPA group was given an intraperitoneal injection of VPA (300 mg/kg) after scalded, Each group was subdivided into two subgroups (n=8) according to the two observation time points of 3h and 6h after scald. Apoptotic cardiomyocytes were observed, and myocardial tissue levels of nitric oxide (NO), cysteine protease-3 (caspase-3) activity, hypoxia-inducible factor-1α (HIF-1α), inducible nitric oxide synthase (iNOS), BCL2/adenovirus E1B interacting protein 3 (BNIP3) and caspase-3 protein were measured. Compared with sham scald group, severe scald elevated CK-MB, cardiomyocyte apoptosis rate, caspase-3 activity and protein levels, NO content, and HIF-1α signalling pathway proteins; whereas VPA decreased CK-MB, cardiomyocyte apoptosis rate and inhibited HIF-1α signalling pathway protein expression. In conclusion, these results suggested that VPA inhibited early cardiomyocyte apoptosis and attenuated myocardial injury in lethally scalded rats, which may be related to the regulation of the HIF-1α signalling pathway.

Superiority of [68Ga]Ga-DOTA-FAPI-04 PET/CT to [18F]FDG PET/CT in the evaluation of thymic epithelial tumours.

PURPOSE: The purpose of this study is to compare the ability of [68Ga]Ga-DOTA-FAPI-04 PET/CT and [18F]FDG PET/CT to stratify the malignancy and invasiveness of thymic epithelial tumours (TETs). METHODS: From April 2021 to November 2022, participants with suspected TETs confirmed by histopathology or follow-up imaging were prospectively analysed. All participants underwent [18F]FDG and [68Ga]Ga-DOTA-FAPI-04 PET/CT within 1 week. Clinical characteristics, CT features, and metabolic parameters (maximum standardized uptake value [SUVmax] and tumour-to-mediastinum ratio [TMR]) of subjects with different pathological types and stages were compared. The diagnostic capacities of [18F]FDG and [68Ga]Ga-DOTA-FAPI-04 PET/CT were compared using receiver operating characteristic (ROC) curves and McNemar's test. RESULTS: Fifty-seven participants were included. [68Ga]Ga-DOTA-FAPI-04 PET/CT was superior to [18F]FDG PET/CT in differentiating thymomas from thymic carcinomas (TCs) (AUC: 0.99 vs. 0.90, P = 0.02). Logistic regression revealed that SUVmax-FAPI (P = 0.04) was a significant predictive factor for TCs. SUVmax-FAPI and TMR-FAPI showed an excellent ability to differentiate low-risk thymomas (types A, AB, and B1), high-risk thymomas (types B2 and B3), and TCs (both P < 0.001). In thymomas, only SUVmax-FAPI (P < 0.001), TMR-FAPI (P < 0.001), and nonsmooth edges (P = 0.02) were significantly higher in the advanced-stage (Masaoka-Koga [MK] stage III/IV) group than in the early-stage group (MK stage I/II). Compared with [18F]FDG PET/CT, [68Ga]Ga-DOTA-FAPI-04 PET/CT showed significantly higher specificity (67% [46 of 69] vs. 93% [64 of 69], P < 0.001) in the detection of lymph node metastases and higher sensitivity (49% [19 of 39] vs. 97% [38 of 39], P < 0.001) in evaluating distant metastases. Both SUVmax-FAPI and TMR-FAPI were correlated with FAP expression (both r = 0.843, P < 0.001). CONCLUSION: [68Ga]Ga-DOTA-FAPI-04 PET/CT was superior to [18F]FDG PET/CT in evaluating the World Health Organization (WHO) classification, MK staging, and metastatic status of TETs. TRIAL REGISTRATION: ChiCTR2000038080, registration date 2020-09-09, https://www.chictr.org.cn/com/25/showproj.aspx?proj=61192.

High in-vivo stability in preclinical and first-in-human experiments with [18F]AlF-RESCA-MIRC213: a 18F-labeled nanobody as PET radiotracer for diagnosis of HER2-positive cancers.

PURPOSE: [18F]AlF-RESCA was introduced as a core particularly useful for 18F-labeling of heat-sensitive biomolecules. However, no translational studies have been reported up to now. Herein, we reported the first-in-human evaluation of an 18F-labeled anti-HER2 nanobody MIRC213 as a PET radiotracer for imaging HER2-positive cancers. METHODS: MIRC213 was produced by E. coli and conjugated with ( ±)-H3RESCA-Mal. [18F]AlF-RESCA-MIRC213 was prepared at room temperature. Its radiochemical purity and stability of were determined by radio-HPLC with the size-exclusion chromatographic column. Cell uptake was performed in NCI-N87 (HER2 +) and MCF-7 (HER2-) cells and the cell-binding affinity was verified in SK-OV-3 (HER2 +) cells. Small-animal PET/CT was performed using SK-OV-3, NCI-N87, and MCF-7 tumor-bearing mice at 30 min, 1 h, and 2 h post-injection. For blocking experiment, excess MIRC213 was co-injected with radiotracer. Biodistribution were performed on SKOV-3 and MCF-7 tumor-bearing mice at 2 h post-injection. For clinical study, PET/CT images were acquired at 2 h and 4 h after injection of [18F]AlF-RESCA-MIRC213 (1.85-3.7 MBq/kg) in six breast cancer patients (3 HER2-positive and 3 HER2-negative). All patients underwent [18F]-FDG PET/CT within a week for tissue selection purpose. Distribution and dosimetry were calculated. Standardized uptake values (SUV) were measured in tumors and normal organs. RESULTS: MIRC213 was produced with > 95% purity and modified with RESCA to obtain RESCA-MIRC213. [18F]AlF-RESCA-MIRC213 was prepared within 20 min at room temperature with the radiochemical yield of 50.48 ± 7.6% and radiochemical purity of > 98% (n > 10), and remained stable in both PBS (88%) and 5% HSA (92%) after 6 h. The 2 h cellular uptake of [18F]AlF-RESCA-MIRC213 in NCI-N87 cells was 11.22 ± 0.60 AD%/105 cells. Its binding affinity Kd value was determined to be 1.23 ± 0.58 nM. Small-animal PET/CT with [18F]AlF-RESCA-MIRC213 can clearly differentiate SK-OV-3 and NCI-N87 tumors from MCF-7 tumors and background with a high uptake of 4.73 ± 1.18 ID%/g and substantially reduced to 1.70 ± 0.13 ID%/g for the blocking group (p < 0.05) in SK-OV-3 tumors at 2 h post-injection. No significant bone radioactivity was seen in the tumor-bearing animals. In all six breast cancer patients, there was no adverse reaction during study. The uptake of [18F]AlF-RESCA-MIRC213 was mainly in lacrimal gland, parotid gland, submandibular gland, thyroid gland, gallbladder, kidneys, liver, and intestines. There was no significant bone radioactivity accumulation in cancer patients. [18F]AlF-RESCA-MIRC213 had significantly higher tumor uptake in lesions from HER2-positive patients than that lesions from HER2-negative patients (SUVmax of 3.62 ± 1.56 vs. 1.41 ± 0.41, p = 0.0012) at 2 h post-injection. The kidneys received the highest radiation dose of 2.42 × 10-1 mGy/MBq, and the effective dose was 1.56 × 10-2 mSv/MBq. CONCLUSIONS: [18F]AlF-RESCA-MIRC213 could be prepared with high radiolabeling yield under mild conditions. [18F]AlF-RESCA-MIRC213 has relatively high stability both in vitro and in vivo. The results from clinical transformation suggest that [18F]AlF-RESCA-MIRC213 PET/CT is a safe procedure with favorable pharmacokinetics and dosimetry profile, and it is a promising new PET radiotracer for noninvasive diagnosis of HER2-positive cancers.

Predictive Value of 18 F-FDG PET/MRI for Pleural Invasion in Solid and Subsolid Lung Adenocarcinomas Smaller Than 3 cm.

BACKGROUND: Positron emission tomography (PET)/MRI combines the characteristics of metabolism imaging and high soft tissue resolution, and could provide high diagnostic efficacy for assessment of pleural invasion (PI) of lung cancer. PURPOSE: To investigate the application of 18 F-fluorodeoxyglucose (FDG) PET/MRI for predicting PI of lung cancer with the maximum diameter ≤3 cm. STUDY TYPE: Prospective. POPULATION: A total of 44 patients with non-small cell lung cancer (NSCLC), age from 39 to 79 years old, including 19 (56.82%) females. FIELD STRENGTH/SEQUENCE: A 3-T, hybrid PET/MRI including axial fast spin echo respiratory-triggered T2 fat-suppressed imaging (T2FS) and echo planar imaging diffusion-weighted imaging (DWI). ASSESSMENT: The maximum standardized uptake value (SUVmax) of all lesions was measured on PET images. Localized effusion outside the contact between the nodules and the pleura on T2FS and signal at the contact between the nodules and the pleura on DWI were evaluated by experienced physicians through visual assessment of the MRI sequences. STATISTICAL TESTS: Three models (models 1-3) were developed, incorporating CT, CT and PET, PET and MRI features, and Lasso regression was used in feature selection. The receiver operating characteristic (ROC) curve for PI diagnosis was visualized for each model, and the area under the curve (AUC) was calculated. The DeLong test was used to compare the different AUCs. A P value < 0.05 was considered statistically significant. RESULTS: The AUC of models 1-3 was 0.762, 0.829, and 0.915, respectively. The DeLong test showed a statistically significant difference between the AUCs of model 1 vs. model 3, while the differences between the AUCs of model 1 vs. model 2 (P = 0.253) and model 2 vs. model 3 (P = 0.075) were not statistically significant. DATA CONCLUSION: 18 F-FDG PET/MRI might show high predictive value for lung adenocarcinoma smaller than 3 cm with PI. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.

Somatostatin Receptor Imaging in Mice with Difference Positive Rate of SSTR2.

INTRODUCTION: Imaging with [68Ga]Ga-DOTA-TATE, [68Ga]Ga-DOTA-JR11 and [18F]AlF-NOTA-JR11 was performed to analyze differences among the three probes, and to analyze the correlation between the image and pathology parameters. METHOD: Tumor bearing mice with different positive rates of somatostatin receptor II (SSTR2) were established with HEK293-SSTR2 and HEK293 cells, and imaging was performed on the same mouse with [68Ga]Ga-DOTA-TATE, [68Ga]Ga-DOTA-JR11 and [18F]AlF-NOTA-JR11 at 20, 60 and 120 min. The image parameters were obtained, including the maximum standard uptake value (SUVmax), mean standard uptake value (SUVmean), standard deviation of SUVmean (SD), tumor volume and coefficient of variation (CoV). Immunohistochemistry of the tumor was performed after imaging to obtain positive rate of SSTR2. Statistical analysis was performed to analyze the differences among the three imaging techniques and the correlations between the relative imaging parameter and immunohistochemistry (IHC). RESULT: The SUVmax of [18F]AlF-NOTA-JR11 at 20 and 60 min was higher than that of [68Ga]Ga-DOTA-TATE (P=0.0015, 0.0035) and [68Ga]Ga-DOTA-JR11 (P=0.033, 0.019), and no significant difference was found in the other groups (P>0.05). There was a significant positive correlation between the positive rate and SUVmean of tumors with three tracers (P<0.05). However, a significant negative correlation between the positive rate and CoV was found only in the [68Ga]Ga-DOTA-TATE group at 60 min and 120 min (P=0.048, 0.026). CONCLUSION: [18F]AlF-NOTA-JR11 is more suitable for SSTR imaging within an hour than other two tracers. SUVmean of whole tumor can become an indicator for evaluating the positive rate of IHC, and the higher SUVmean of three tracers means a higher positive rate. However, the CoV is not applicable to the two antagonist tracers for evaluating the positive rate.

Study on an Animal Model of Seawater Immersion Injury Following Hemorrhagic Shock.

INTRODUCTION: To establish an animal model of delayed intravenous resuscitation following seawater immersion after hemorrhagic shock (HS). METHODS: Adult male SD rats were randomly divided into three groups: group NI (HS with no immersion), group SI (HS with skin immersion), and group VI (HS with visceral immersion). Controlled HS in rats was induced by withdrawing 45% of the calculated total blood volume within 30 min. In SI group, immediately after blood loss, 0.5 cm below the xiphoid process was immersed in artificial seawater, at (23 ± 1) °C, for 30 min. In VI group, the rats were performed by laparotomy and the abdominal organs were immersed in (23 ± 1) °C seawater for 30 min. Two hours after seawater immersion, the extractive blood and lactated Ringer's solution were delivered intravenously. The mean arterial pressure (MAP), lactate, and other biological parameters were investigated in different time points. The survival rate of 24 h after HS was recorded. RESULTS: After seawater immersion following HS, MAP and abdominal viscera blood flow decreased significantly, and the plasma levels of lactate and the organ function parameters were increased than the baseline. The above changes in VI group were more serious than those in SI and NI group, especially in myocardial and small intestine damage. The hypothermia, hypercoagulation, and metabolic acidosis were also observed after seawater immersion; the injury was more severely in VI group than that of SI group. However, the plasma levels of sodium, potassium, chlorine, and calcium in VI group were significantly higher than those before injury and in the other two groups. In the VI group, the level of plasma osmolality in instant, 2 h, and 5 h after immersion was 111%, 109%, and 108% of the SI group, respectively, all P < 0.01. The 24-h survival rate of VI group was 25%, which was significantly lower than that of SI group (50%) and NI group (70%), P < 0.05. CONCLUSIONS: The model fully simulated the key damage factors and field treatment conditions, reflected the effects of low temperature and hypertonic damage caused by seawater immersion on the severity and prognosis of naval combat wounds, and provided a practical and reliable animal model for the study of field treatment technology of marine combat shock.

Higher accuracy of [68 Ga]Ga-DOTA-FAPI-04 PET/CT comparing with 2-[18F]FDG PET/CT in clinical staging of NSCLC.

PURPOSE: This study aimed to explore the clinical staging performance of [68 Ga]Ga-DOTA-FAPI-04 PET/CT compared with that of 2-[18F]FDG PET/CT in non-small cell lung cancer (NSCLC) patients lesion by lesion. METHODS: A total of 134 diagnosed or suspected NSCLC patients were enrolled in the prospective study (ChiCTR2000038080); they received paired 2-[18F]FDG PET/CT and [68 Ga]Ga-DOTA-FAPI-04 PET/CT. Of these patients, the retrospective analysis of 74 NSCLC patients with pathological results was conducted from primary tumor (T) diagnosis, lymph node (N), and metastatic lesion (M) staging. The imaging characteristics of the lung nodules and suspected metastases were obtained and analyzed, and the staging performance of 2-[18F]FDG PET/CT and [68 Ga]Ga-DOTA-FAPI-04 PET/CT was compared. RESULTS: For T diagnosis, [68 Ga]Ga-DOTA-FAPI-04 showed better diagnostic performance than 2-[18F]FDG in 79 lung nodules of 72 patients, especially for nonsolid and small-dimension adenocarcinoma nodules. For N staging, 98 lymph nodes (LNs) with pathological results in 37 patients were analyzed. The SUVmax of [68 Ga]Ga-DOTA-FAPI-04 in the nonmetastatic LNs was significantly lower than that in the metastatic LNs. Regarding metastatic LN identification, the calculated optimum cut-off value of [68 Ga]Ga-DOTA-FAPI-04 SUVmax was 5.5, and the diagnostic accuracy using [68 Ga]Ga-DOTA-FAPI-04 and 2-[18F]FDG criteria was 94% and 30%, respectively (P < 0.001). For M staging, [68 Ga]Ga-DOTA-FAPI-04 identified more lesions than 2-[18F]FDG (257 vs. 139 lesions) in 14 patients with multiple metastases. Overall, the staging accuracy of [68 Ga]Ga-DOTA-FAPI-04 was better than that of 2-[18F]FDG in 52 patients with different pathological stages [43/52 (82.7%) vs. 27/52 (51.9%), P = 0.001]. CONCLUSION: Compared with 2-[18F]FDG PET/CT, [68 Ga]Ga-DOTA-FAPI-04 PET/CT demonstrated better staging performance in NSCLC patients with different pathological stages, especially those with localized disease.

Construction of a 124I-Labeled Specific Antibody for the Noninvasive Detection of Mesothelin-Overexpressing Tumors.

Mesothelin (MSLN) is a molecular biomarker of many types of solid tumors, such as mesothelioma, pancreatic cancer, and colon cancer. Owing to the significant difference in expression between cancer cells and normal cells, mesothelin has been widely used as a key target in cancer immunotherapy. In this study, we used iodine isotope (nat/124/125I)-labeled mesothelin antibodies to noninvasively detect MSLN expression in mice with LS174T colon cancer. The 124I-labeled MSLN antibody showed a high radiochemical purity (RCP, >99%) and specific activity (20.8-67.8 GBq/µmol) after purification and was stable in 5% HSA and PBS (>95% RCP at 8 days). Western blot analysis indicated that the LS174T cells showed a higher MSLN protein level than the HepG2 cells. The half maximal effective concentration (EC50) values of the MSLN antibody and natI-anti-MSLN were 34.77 ± 3.72 ng/mL and 32.60 ± 2.52 ng/mL (P = 0.63), respectively. The dissociation constant of 124I-anti-MSLN binding to MSLN protein was 16.0 nM. The radiotracer showed a significantly higher uptake in LS174T cells than in HepG2 tumor cells (1.56 ± 0.09 vs 0.81 ± 0.03, P = 0.0016) 2 days postinjection. The LS174T mouse models showed extremely low organ uptake and high tumor uptake 96 h after the injection of 124I-anti-MSLN, and the T/M values were much higher than those of the other imaging groups (10.56 ± 1.20 for 124I-anti-MSLN in LS174T mice vs 3.27 ± 0.20 for 124I-anti-MSLN in HepG2 mice vs 3.53 ± 0.2 for 124I-IgG in LS174T mice). The immunochemical histology results showed that LS174T tumors were strongly positive (+++) for MSLN, while those in the HepG2 group showed slight expression (+). The dosimetry estimation study showed that the effective dose of 124I-anti-MSLN was 0.185 mSv/MBq, which is within the range of acceptable doses for further nuclear medicine translational research. Taken together, these results suggest that this radiotracer has the potential for detecting mesothelin-overexpressing tumors.

Targeting Claudin 18.2 Using a Highly Specific Antibody Enables Cancer Diagnosis and Guided Surgery.

Claudin 18.2 (CLDN18.2) is a new potential target for cancer therapy, especially for advanced gastric cancer (AGC). A molecular targeting probe is of importance for patient stratification and therapeutic guidance. Here, we explored an antibody-dependent molecular imaging strategy for specific detection and surgery guidance based on a CLDN18.2-specific antibody, 5C9. Two imaging probes, 124I-5C9 and Cy5.5-5C9, were synthesized. The specificity to CLDN18.2 being evidenced in the cellular experiments with control, the diagnostic utility was assessed by immunopositron emission tomography (immuno-PET) and fluorescence imaging using xenograft models. A near-infrared fluorescent II imaging probe FD1080-5C9 was designed to facilitate the comprehensive surgical removal of lesions. 124I-5C9 immuno-PET imaging clearly delineated subcutaneous CLDN18.2-positive tumors, with a peak uptake (maximum standardized uptake value; SUVmax) of 2.25 ± 0.30, whereas the highest values for the 124I-IgG and blocking groups were 0.70 ± 0.13 and 0.66 ± 0.12, respectively. Cy5.5-5C9 fluorescence imaging showed similar results. As proof of the diagnosis and guided surgery (DGS) concept, 124I-5C9 and FD1080-5C9 were simultaneously administered in orthotopic CLDN18.2-positive tumor models, facilitating the comprehensive resection of tumor tissue. Combined, 124I-5C9 and FD1080-5C9 are both promising DGS tools: the former reveals CLDN18.2 in lesions as a PET probe, and the latter can guide surgery. These results provide a utility molecular imaging strategy for specific detection and surgery guidance based on a CLDN18.2-specific antibody both in AGC and other cancers.

SARS-CoV-2 receptor binding domain radio-probe: a non-invasive approach for angiotensin-converting enzyme 2 mapping in mice.

The spike protein of SARS-CoV-2 interacts with angiotensin-converting enzyme 2 (ACE2) of human respiratory epithelial cells, which leads to infection. Furthermore, low-dose radiation has been found to reduce inflammation and aid the curing of COVID-19. The receptor binding domain (RBD), a recombinant spike protein with a His tag at the C-terminus, binds to ACE2 in human body. We thus constructed a radioiodinated RBD as a molecule-targeted probe to non-invasively explore ACE2 expression in vivo, and to investigate radiotherapy pathway for inhibiting ACE2. RBD was labeled with [124I]NaI using an N-bromosuccinimide (NBS)-mediated method, and 124I-RBD was obtained after purification with a specific activity of 28.9 GBq/nmol. Its radiochemical purity was (RCP) over 90% in saline for 5 days. The dissociation constant of 124I-RBD binding to hACE2 was 75.7 nM. The uptake of 124I-RBD by HeLaACE+ cells at 2 h was 2.96% ± 0.35%, which could be substantially blocked by an excessive amount of RBD, and drop to 1.71% ± 0.23%. In BALB/c mice, the biodistribution of 124I-RBD after intravenous injection showed a moderate metabolism rate, and its 24 h-post injection (p.i.) organ distribution was similar to the expression profile in body. Micro-PET imaging of mice after intrapulmonary injection showed high uptake of lung at 1, 4, 24 h p.i.. In conclusion, the experimental results demonstrate the potential of 124I-RBD as a novel targeted molecular probe for COVID-19. This probe may be used for non-invasive ACE2 mapping in mammals.

Initial evaluation of 99m Tc-labeled anti-carcinoembryonic antigen single-chain fragment variable for micro-single-photon emission computed tomography imaging in mice with colorectal cancer.

Carcinoembryonic antigen (CEA) has emerged as an important molecular target for several neoplastic diseases, including colorectal cancer with CEA over-expression. In this study, we report the production and radiolabeling of a novel anti-CEA single-chain fragment variable (scFv-96NRT, concentration for 50% of maximal effect 46 ng/ml), and evaluation of [99m Tc]Tc-scFv-96NRT in non-invasive detection of CEA expression. [99m Tc]Tc-scFv-96NRT was synthesized by one step reduction in labeling yield of >95% with radiochemical purity of >98% and molar activity of 10-11 GBq/µmol. [99m Tc]Tc-scFv-96NRT showed high stability in 0.01 M phosphate-buffered saline (PBS) and 5% human serum albumin (HSA). It exhibited elevated uptake in CEA over-expressing cells. Biodistribution studies in BALB/c mice revealed that the probe was cleared from blood rapidly, and the highest retention was observed in the kidneys. The micro-single-photon emission computed tomography (micro-SPECT) imaging of [99m Tc]Tc-scFv-96NRT showed a specific accumulation pattern, as blocking experiment with excess scFv-96NRT suppressed the tumor uptake. These preliminary results suggest that [99m Tc]Tc-scFv-96NRT is a potential non-invasive molecular probe for imaging tumors with CEA over-expression.

A Highly Specific Multiple Enhancement Theranostic Nanoprobe for PET/MRI/PAI Image-Guided Radioisotope Combined Photothermal Therapy in Prostate Cancer.

An integrated molecular probe for combined tumor-targeted multimodal imaging and therapy in the era of precision medicine requires a multiplexed platform that simultaneously has high targeting specificity, versatile conjugation capability, and biocompatibility. Here, a novel biocompatible melanin nanoprobe (PMNs-II-813) coupled with a highly specific prostate-specific membrane antigen small molecule inhibitor is developed for the targeted multimodal diagnosis and treatment of prostate cancer. The melanin nanoparticles demonstrate photoacoustic imaging and photothermal therapy (PTT) functionalities via strong near-infrared absorption. The imaging contrast agents 89 Zr and Mn2+ are stably conjugated to the nanoparticles for positron emission tomography (PET) and magnetic resonance imaging (MRI). Fusion PET/MRI with PMNs-II-813 enables the monitoring of treatment effects in real time and lasts for more than 1 week, demonstrating the capability for multimodal theranostics in prostate cancer. Labeling with a therapeutic radionuclide, 131 I, simultaneously endows the nanoprobe with the capability for radioisotope therapy (RIT) and PTT under triple-modal imaging guidance. Combined PTT and RIT has an inhibitory effect on prostate cancer growth (tumor inhibition rate of ≈93% 20 days after treatment), which is significantly better than that with the single treatment. Overall, it is believed that PMNs-II-813 has potential for clinical translation to treat prostate cancer.

Synthesis, preclinical evaluation, and a pilot clinical imaging study of [18F]AlF-NOTA-JR11 for neuroendocrine neoplasms compared with [68Ga]Ga-DOTA-TATE.

PURPOSE: A [18F]AlF-labeled somatostatin receptor (SSTR) antagonist was developed for imaging of neuroendocrine neoplasms (NENs), evaluated and compared with [68Ga]Ga-DOTA-TATE. METHOD: [18F]AlF-NOTA-JR11 was synthesized manually and qualified with high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). The cellular uptake, internalization, and saturation binding were performed with HEK293-SSTR2 cells. Biodistribution and micro-PET imaging were carried out with HEK293-SSTR2 tumor-bearing mice. [18F]AlF-NOTA-JR11 PET/MR imaging and [68Ga]Ga-DOTA-TATE PET/CT were performed with ten patients of NEN at 50~60 min post-injection (p.i.). Normal organ biodistribution and tumor detectability were evaluated. RESULT: [18F]AlF-NOTA-JR11(24~36 GBq/µmol) was prepared within 30 min and 51.35 ± 3.30% (n > 10)of radiochemical yield. The radiochemical purity was 98.74 ± 1.24% (n > 10). Two stereoisomers were found and confirmed by LC-MS. The cellular uptake of [18F]AlF-NOTA-JR11 and [68Ga]Ga-DOTA-TATE were 4.50 ± 0.31 and 4.50 ± 0.13 %AD/105 cells at 30 min, and the internalization at 37 °C of [18F]AlF-NOTA-JR11 (5.47 ± 0.32% at 60 min) was significantly lower than [68Ga]Ga-DOTA-TATE (66.89 ± 1.62% at 60 min). The affinity of [18F]AlF-NOTA-JR11 (Kd = 11.59 ± 1.31 nM) was slightly lower than [68Ga]Ga-DOTA-TATE (Kd = 7.36 ± 1.02 nM); [18F]AlF-NOTA-JR11 showed high uptake in tumor (9.02 ± 0.92 %ID/g at 60 min p.i.) which can be blocked by 50 µg of NOTA-JR11 (3.40 ± 1.64 %ID/g at 60 min p.i.); the result was coincident with micro-PET imaging. Imaging study of NEN patients showed that more lesions were found only by [18F]AlF-NOTA-JR11 (n = 67 vs. 1 only by [68Ga]Ga-DOTA-TATE), and the uptakes of [18F]AlF-NOTA-JR11 in majority normal organs were significantly lower than [68Ga]Ga-DOTA-TATE. The target to nontarget of maximum of standard uptake value (SUVmax) of [18F]AlF-NOTA-JR11 in liver lesions were significantly higher than those of [68Ga]Ga-DOTA-TATE. CONCLUSION: Qualitied [18F]AlF-NOTA-JR11 is prepared conveniently with reasonable yield, and it can bind SSTR2 specifically with high affinity. Excellent imaging capability of [18F]AlF-NOTA-JR11 for NENs is superior to [68Ga]Ga-DOTA-TATE, especially in digestive system. It has a great potential for imaging of NENs.

Noninvasive evaluation of PD-L1 expression using Copper 64 labeled peptide WL12 by micro-PET imaging in Chinese hamster ovary cell tumor model.

As an indicative biomarker for immunotherapy, PD-L1 plays an important role in the clinical decision-making of the immune checkpoint blockade therapy. PET imaging through radiotracer can real-timely, quantitatively, and non-invasively assess the expression of PD-L1 in tumors. Here, we reported a copper-64 radiolabeled NOTA-WL12, 64Cu-NOTA-WL12, and preliminarily evaluated its application in non-invasively detecting the PD-L1 expression.64Cu-NOTA-WL12 was produced with high radiochemical yield (>90%), radiochemical purity (>98%), and specific activity (20 MBq/nmol). 64Cu-NOTA-WL12 showed high in vitro stability and high binding affinity to the PD-L1 (KD ≈ 3.012 nM). The micro-positron emission tomography/computerized tomography (micro-PET/CT) imaging indicated that 64Cu-NOTA-WL12 was specifically accumulated in the tumor with PD-L1 expression. All results demonstrated that 64Cu-NOTA-WL12 holds great potential for noninvasive evaluation of PD-L1 expression levels.

De novo biosynthesis and gram-level production of m-cresol in Aspergillus nidulans.

The industrially important meta-cresol (m-cresol, 3-methylphenol) is mainly produced from fossil resources by chemical methods. The microbial production of m-cresol was rarely investigated. Herein, we constructed a platform for the overproduction of m-cresol in a modified fungus Aspergillus nidulans FGSC no. A1145∆ST∆EM, which gave a gram-level titer using starch as carbon resource. For the biosynthesis of m-cresol, the 6-methyl salicylic acid synthase (MSAS)-encoding gene patK and 6-methyl salicylic acid decarboxylase-encoding gene patG from A. clavatus were co-expressed in the host A. nidulans. Multiple strategies, including promotor engineering, gene multiplication, and fed-batch fermentation, were applied to raise the production of m-cresol, which resulted in the titers of 1.29 g/L in shaking flasks and 2.03 g/L in fed-batch culture. The chassis cell A. nidulans A1145∆ST∆EM was proved to possess better tolerance to m-cresol than yeast, as it could grow in the liquid medium containing up to 2.5 g/L of m-cresol. These results showed that A. nidulans has great potential to be further engineered for industrial production of m-cresol.Key points• m-Cresol was de novo biosynthesized by a fungal chassis cell Aspergillus nidulans.• Promoter engineering and gene multiplication implemented the fine-tuned genes expression.• The titer of m-cresol reached 2.03 g/L via fed-batch culture.

d-Sedoheptulose-7-phosphate is a common precursor for the heptoses of septacidin and hygromycin B.

Seven-carbon-chain-containing sugars exist in several groups of important bacterial natural products. Septacidin represents a group of l-heptopyranoses containing nucleoside antibiotics with antitumor, antifungal, and pain-relief activities. Hygromycin B, an aminoglycoside anthelmintic agent used in swine and poultry farming, represents a group of d-heptopyranoses-containing antibiotics. To date, very little is known about the biosynthesis of these compounds. Here we sequenced the genome of the septacidin producer and identified the septacidin gene cluster by heterologous expression. After determining the boundaries of the septacidin gene cluster, we studied septacidin biosynthesis by in vivo and in vitro experiments and discovered that SepB, SepL, and SepC can convert d-sedoheptulose-7-phosphate (S-7-P) to ADP-l-glycero-ß-d-manno-heptose, exemplifying the involvement of ADP-sugar in microbial natural product biosynthesis. Interestingly, septacidin, a secondary metabolite from a gram-positive bacterium, shares the same ADP-heptose biosynthesis pathway with the gram-negative bacterium LPS. In addition, two acyltransferase-encoding genes sepD and sepH, were proposed to be involved in septacidin side-chain formation according to the intermediates accumulated in their mutants. In hygromycin B biosynthesis, an isomerase HygP can recognize S-7-P and convert it to ADP-d-glycero-ß-d-altro-heptose together with GmhA and HldE, two enzymes from the Escherichia coli LPS heptose biosynthetic pathway, suggesting that the d-heptopyranose moiety of hygromycin B is also derived from S-7-P. Unlike the other S-7-P isomerases, HygP catalyzes consecutive isomerizations and controls the stereochemistry of both C2 and C3 positions.

Graphene/Intermetallic PtPb Nanoplates Composites for Boosting Electrochemical Detection of H2O2 Released from Cells.

Rational design and construction of electrocatalytic nanomaterials is vital for improving the sensitivity and selectivity of nonenzymatic electrochemical sensors. Here, we report a novel graphene supported intermetallic PtPb nanoplates (PtPb/G) nanocomposite as an enhanced electrochemical sensing platform for high-sensitivity detection of H2O2 in neutral solution and also released from the cells. The intermetallic PtPb nanoplates are first synthesized via a simple wet-chemistry process and subsequently assembled on graphene via a solution-phase self-assembly approach. The obtained nanocomposite exhibits excellent electrocatalytic activity for the electrochemical reduction of H2O2 in a half-cell test and can detect H2O2 with a wide linear detection range of 2 nM to 2.5 mM and a very low detection limit of 2 nM. Under the same conditions, the sensitivity of PtPb/G for the detection of H2O2 is more than 12.7 times higher than that of commercial Pt/C. The high-density of electrocatalytic active sites on the unique PtPb nanoplates and the synergistic effect between PtPb nanoplates and graphene appear to be the main factors in contributing to the outstanding electroanalytical performance. The PtPb/G can be also used for the practical detection of H2O2 released from Raw 264.7 cells.

Establishing Reliable Cu-64 Production Process: From Target Plating to Molecular Specific Tumor Micro-PET Imaging.

Copper-64 is a useful radioisotope for positron emission tomography (PET). Due to the wide range of applications, the demand of 64Cu with low metallic impurities is increasing. Here we report a simple method for the efficient production of high specific activity 64Cu using a cyclotron for biomedical application. We designed new equipment based on the plating of enriched 64Ni as the target, and used automated ion exchange chromatography to purify copper-64 efficiently after irradiation and dissolution of the target in good radiochemical and chemical yield and purity. The 64Cu radionuclide produced using 99.32% enriched 64Ni with a density of 61.4 ± 5.0 mg/cm², reaching a total radioactivity greater than 200 mCi, with specific activity up to 5.6 GBq/µmoL. It was further incorporated into modified monoclonal antibody DOTA-rituximab to synthesize 64Cu-DOTA-rituximab, which was used successfully for micro-PET imaging.