Background: 68 Ga-NOTA-WL12 is a peptide-based positron emission tomography (PET) imaging agent. We conducted a first-in-human study of 68 Ga-NOTA-WL12 for PET to study the in vivo biodistribution, metabolism, radiation dosimetry, safety, and potential for quantifying programmed death ligand-1 (PD-L1) expression levels in advanced non-small cell lung cancer (NSCLC) patients. Methods: In vitro assessment of the PD-L1 expression and cellular uptake of 68 Ga-NOTA-WL12 were performed, followed by in vivo evaluation of 68 Ga-NOTA-WL12 uptake in mouse models with tumors. Nine NSCLC patients with lesions expressing PD-L1 were enrolled and monitored for adverse events during the study. 68 Ga-NOTA-WL12 and paired 18 F-FDG PET/CT imaging were performed. Uptake (SUV/L and kBq/mL) values of tumors and normal organs were obtained.Radiopharmaceutical biodistribution, radiation dosimetry and the relationship of tumor uptake to PD-L1 expression were evaluated. Follow-up 18 F-FDG PET/CT was performed in patients who had undergone treatment with a combination of pembrolizumab with chemotherapy. Results: 68 Ga-NOTA-WL12 exhibited PD-L1 specific uptake in vitro and in PD-L1-positive tumors in vivo. 68 Ga-NOTA-WL12 PET imaging proved safe with acceptable radiation dosimetry. Physiological tracer uptake was mainly visible in the liver, spleen, small intestine and kidney. Tumors were clearly visible, particularly in the lungs, with a T/lung ratio of 4.45 ±1.89 at 1 h. One hour was a suitable time-point for image acquisition because no significant differences were noted in tumor-to-background ratios between 1 and 2 h. A strong, positive correlation was found between tumor uptake (SUVpeak) and PD-L1 immunohistochemistry results (r = 0.9349; P = 0.002). 68 Ga-NOTA-WL12 and 18 F-FDG PET studies suggest that PD-L1 PET before therapy may indicate the therapeutic efficacy of pembrolizumab plus chemotherapy combination treatment. Conclusions: Our first-in-human findings demonstrate the safety and feasibility of 68 Ga-NOTA-WL12 for noninvasive, in vivo detection of tumor PD-L1 expression levels, indicating potential benefits for clinical PD-L1 therapy.

Semi-quantitative analysis indexes of Ga-PSMA-617 PET/CT imaging can be used as "imaging biomarkers" to predict risk stratification and metastatic risk of prostate cancer.

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parameters to predict the outcome of repeat prostate biopsy. Results: The median age of patients was 65 years (range 53-81), and the median PSA level was 18.0 ng/ml (range 5.48-49.77 ng/ml). Prostate cancer was detected in 15/31 patients (48.4%) and 12/31 patients (38.7%) had clinically significant disease. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 68 Ga-PSMA PET/CT in the diagnosis of clinically significant prostate cancer were 100.0%, 68.4%, 66.7%, 100.0% and 80.6%, respectively. The detection rate of prostate cancer increased with the increase of miPSMA-ES score. The detection rate of clinically significant prostate cancer in miPSMA-ES 0-1, 2 and 3 groups were 0%, 54.5% and 85.7% respectively. Semi-quantitative analysis of 68 Ga-PSMA PET/CT images showed that predictive models based on maximum standardized uptake value (SUVmax), tumor-to-background normal prostate SUV (SUVT/BGp) and tumor-to-background normal liver SUV (SUVratio) could effectively predict clinically significant prostate cancer; area under the curves were 0.930, 0.877, and 0.956, respectively. Conclusion: This study preliminarily confirmed that 68 Ga-PSMA PET/CT imaging combined with PET-ultrasound fusion image-guided prostate biopsy can effectively detect clinically significant prostate cancer. Prebiopsy 68 Ga-PSMA PET/CT has predictive value for clinically significant cancer in the studied patient population.

Rapid progress has been made to identify and study the causative agent leading to coronavirus disease 2019 (COVID‐19) but many questions including who is most susceptible and what determines severity remain unanswered. Angiotensin‐converting enzyme 2 (ACE2) is a key factor in the infection process of severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2). In this study, molecularly specific positron emission tomography imaging agents for targeting ACE2 are first developed, and these novel agents are evaluated in vitro, in preclinical model systems, and in a first‐in‐human translational ACE2 imaging of healthy volunteers and a SARS‐CoV‐2 recovered patient (NCT04422457). ACE2 expression levels in different organs in live subjects are quantitatively delineated and observable differences are measured in the patient recovered from COVID‐19. Surprising sites of uptake in the breast, reproductive system and very low uptake in pulmonary tissues are reported. This novel method can add a unique tool to facilitate SARS‐CoV‐2 related research and improve understanding of this enigmatic disease. Molecular imaging provides quantitative annotation of ACE2, the SARS‐CoV‐2 entry receptor, to noninvasively monitor organs impacted by the COVID‐19.

Purpose Here, we sought to develop a PET radioligand based on trastuzumab labeled with 124 I, 124 I-trastuzumab, to evaluate its distribution, internal dosimetry, and initial PET images of HER2-positive lesions in gastric cancer (GC) patients. Methods In animal studies, micro-PET imaging and bio-distribution were performed to examine the specificity of 124 I-trastuzumab in HER2-positive and HER2-negative mouse models. Subsequently, 124 I-trastuzumab was applied in human clinic trial. Six gastric cancer patients with metastases underwent 124 I-trastuzumab PET imaging, with 18 F-FDG PET/CT in each to compare. Results In animal studies, PET imaging of 124 I-trastuzumab showed significant higher tumor uptake than that of 124 I-IgG1 in HER2-positive PDX mouse models at 24 h. The low tumor uptake of 124 I-trastuzumab in HER2-negative PDX models further confirmed the specificity. In human clinical studies, 18 HER2-positive lesions and 11 HER2-negative lesions were evaluated in PET imaging analysis. The detection sensitivity of 124 I-trastuzumab was 100% (18/18) at 24 h. The PET images showed significant difference in tumor uptake between HER2-positive and HER2-negative lesions at 24 h (SUVmax 7.83 ± 0.55 vs. 1.75 ± 0.29, p < 0.0001). Quite striking difference in tumor uptake was observed between 124 I-trastuzumab and 18 F-FDG (SUVmax 1.75 ± 0.29 vs. 6.46 ± 0.44, p < 0.0001) in HER2-negative lesions, further confirming the specific binding of 124 I-trastuzumab in HER2-positive lesions. The radiation-absorbed dose was calculated to be 0.3011 ± 0.005 mSv/MBq. No toxicities or adverse effects were observed in any of the patients. ConclusionThe findings described here demonstrated that 124 I-trastuzumab was feasible to detect HER2-positive lesions in primary and metastatic gastric cancer patients and to differentiate HER2-positive and HER2-negative lesions quantitatively.Xiaoyi Guo, Nina Zhou, and Zuhua Chen have contributed equally to this work.

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 Mn 2+ 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.

The purpose of this study was to establish the quality control and quantify the novel 64Cu-NOTA-Trastuzumab in gastric cancer patient-derived xenografts (PDX) mice models and patients by applying the molecular imaging technique. Trastuzumab was labeled with 64Cu using NCS-Bz-NOTA as bifunctional chelator, and hIgG1 was labeled with the same procedures as a negative control agent. HER2-positive (case 176, n = 12) and HER2-negative (case 168, n = 3) PDX models were established and validated by Western blot, DNA amplification, and immunohistochemistry (IHC). Both models were conducted for micro-PET imaging by tail injection of 18.5 MBq of 64Cu-NOTA-Trastuzumab or 64Cu-NOTA-hIgG1. Radioprobe uptake in tumor and main organs was quantified by region of interested (ROI) analysis of the micro-PET images and autoradiography. Finally, gastric cancer patients were enrolled in preliminary 64Cu-NOTA-Trastuzumab PET/CT scans. NOTA-Trastuzumab was efficiently radiolabeled with 64Cu over a 99% radiochemical purity and 17.5 GBq/μmol specific activity. The immune activity was preserved as the nonmodified antibody, and the radiopharmaceutical proved to be stable for up to 5 half-decay lives of 64Cu both in vitro and in vivo. Two serials of PDX gastric cancer models were successfully established: case 176 for HER2 positive and case 168 for HER2 negative. In micro-PET imaging studies, 64Cu-NOTA-Trastuzumab exhibits a significant higher tumor uptake (11.45 ± 0.42 ID%/g) compared with 64Cu-NOTA-IgG1 (3.25 ± 0.28 ID%/g, n = 5, p = 0.0004) at 36 h after intravenous injection. Lower level uptake of 64Cu-NOTA-Trastuzumab (6.35 ± 0.48 ID%/g) in HER2-negative PDX tumor models further confirmed specific binding of the radioprobe. Interestingly, the coinjection of 2.0 mg of Trastuzumab (15.52 ± 1.97 ID%/g) or 2.0 mg of hIgG1 (15.64 ± 3.54 ID%/g) increased the 64Cu-NOTA-Trastuzumab tumor uptake in PDX tumor (HER2+) models compared with 64Cu-NOTA-Trastuzumab alone (p < 0.05) at 36 h postinjection. There were good correlations between micro-PET images and IHC (n = 4) and autoradiography in PDX (HER2+) tumor tissues. Therefore, 64Cu-NOTA-Trastuzumab successfully translated to clinical PET imaging, and 64Cu-NOTA-Trastuzumab PET/CT scan in gastric cancer patients showed good detection ability. In conclusion, we reported quality control and application of novel 64Cu-NOTA-Trastuzumab for HER2 expression in PDX gastric cancer mice models and gastric cancer patients. Moreover, 64Cu-NOTA-Trastuzumab holds great potential for noninvasive PET detection, staging, and follow-up of HER2 expression in gastric cancer.