Imaging angiogenesis in patients with head and neck squamous cell carcinomas by [68Ga]Ga-DOTA-E-[c(RGDfK)]2 PET/CT

A comparison of [18F]AlF- and 68Ga-labeled dual targeting heterodimer FAPI-RGD in malignant tumor: preclinical evaluation and pilot clinical PET/CT imaging

Due to the heterogeneity of tumors, strategies to improve the effectiveness of dual-targeting tracers in tumor diagnostics have been intensively practiced. In this study, the radiolabeled [18F]AlF-NOTA-FAPI-RGD (denoted as [18F]AlF-LNC1007), a dual-targeting heterodimer tracer targeting both fibroblast activation protein (FAP) and integrin αvβ3 to enhance specific tumor uptake and retention, was synthesized and evaluated. The tracer was compared with [68Ga]Ga-LNC1007 in preclinical and clinical settings.

METHODS

The preparation of [18F]AlF- and 68Ga-labeled FAPI-RGD was carried out with an optimized protocol. The stability was tested in PBS and fetal bovine serum (FBS). Cellular uptake and in vivo distribution of the two products were compared and carried out on the U87MG cell line and its xenograft model. The safety and dosimetry of [18F]AlF-LNC1007 PET/CT scan were evaluated in six patients with malignant tumors.

RESULTS

Two radiolabeling protocols of [18F]AlF-/[68Ga]Ga-LNC1007 were developed and optimized to give a high yield of tracers with good stability. In vivo microPET images showed that the two tracers exhibited comparable pharmacokinetic characteristics, with high tumor uptake and prolonged tumor retention. In vivo distribution data showed that the target-to-non-target ratios of [18F]AlF-LNC1007 were similar to[68Ga]Ga-LNC1007. A total of six patients underwent [18F]AlF-LNC1007 PET/CT evaluation while two had head-to-head [18F]FDG PET/CT scans. The total body effective dose was 9.94E-03 mSv/MBq. The biodistribution curve showed optimal normal organ uptake with high tumor uptake and long retention of up to 3h p.i., and notably, the tumor-to-background ratio increased over time.

CONCLUSION

We successfully prepared an [18F]AlF-LNC1007 dual-targeting PET probe with comparable performances as [68Ga]Ga-LNC1007. With prolonged tumor retention and tumor specificity, it produced good imaging quality in preclinical and clinical translational studies, indicating that [18F]AlF-LNC1007 is a promising non-invasive tracer for detecting tumors expressing FAP and/or integrin avβ3, with the prospect of clinical implementation.

Gallium-68 labelled RGD PET/CT imaging of endothelial activation in COVID-19 patients

In coronavirus disease 2019 (COVID-19), endothelial cells play a central role and an inadequate response is associated with vascular complications. PET imaging with gallium-68 labelled RGD-peptide (⁶⁸Ga-RGD) targets α_vβ₃ integrin expression which allows quantification of endothelial activation. In this single-center, prospective observational study, we included ten hospitalized patients with COVID-19 between October 2020 and January 2021. Patients underwent ⁶⁸Ga-RGD PET/CT followed by iodine mapping of lung parenchyma. CT-based segmentation of lung parenchyma, carotid arteries and myocardium was used to quantify tracer uptake by calculating standardized uptake values (SUV). Five non-COVID-19 patients were used as reference. The study population was 68.5 (IQR 52.0-74.5) years old, with median oxygen need of 3 l/min (IQR 0.9-4.0). ⁶⁸Ga-RGD uptake quantified as SUV ± SD was increased in lungs (0.99 ± 0.32 vs. 0.45 ± 0.18, p < 0.01) and myocardium (3.44 ± 1.59 vs. 0.65 ± 0.22, p < 0.01) of COVID-19 patients compared to reference but not in the carotid arteries. Iodine maps showed local variations in parenchymal perfusion but no correlation with SUV. In conclusion, using ⁶⁸Ga-RGD PET/CT in COVID-19 patients admitted with respiratory symptoms, we demonstrated increased endothelial activation in the lung parenchyma and myocardium. Our findings indicate the involvement of increased and localized endothelial cell activation in the cardiopulmonary system in COVID-19 patients.Trail registration: NCT04596943.

89Zr-panitumumab Combined With 18F-FDG PET Improves Detection and Staging of Head and Neck Squamous Cell Carcinoma

PURPOSE

Determine the safety and specificity of a tumor-targeted radiotracer (89Zr-pan) in combination with 18F-FDG PET/CT to improve diagnostic accuracy in head and neck squamous cell carcinoma (HNSCC).

EXPERIMENTAL DESIGN

Adult patients with biopsy-proven HNSCC scheduled for standard-of-care surgery were enrolled in a clinical trial and underwent systemic administration of 89Zirconium-panitumumab and panitumumab-IRDye800 followed by preoperative 89Zr-pan PET/CT and intraoperative fluorescence imaging. The sensitivity, specificity, and AUC were evaluated.

RESULTS

A total of fourteen patients were enrolled and completed the study. Four patients (28.5%) had areas of high 18F-FDG uptake outside the head and neck region with maximum standardized uptake values (SUVmax) greater than 2.0 that were not detected on 89Zr-pan PET/CT. These four patients with incidental findings underwent further workup and had no evidence of cancer on biopsy or clinical follow-up. Forty-eight lesions (primary tumor, LNs, incidental findings) with SUVmax ranging 2.0-23.6 were visualized on 18F-FDG PET/CT; 34 lesions on 89Zr-pan PET/CT with SUVmax ranging 0.9-10.5. The combined ability of 18F-FDG PET/CT and 89Zr-pan PET/CT to detect HNSCC in the whole body was improved with higher specificity of 96.3% [confidence interval (CI), 89.2%-100%] compared to 18F-FDG PET/CT alone with specificity of 74.1% (CI, 74.1%-90.6%). One possibly related grade 1 adverse event of prolonged QTc (460 ms) was reported but resolved in follow-up.

CONCLUSIONS

89Zr-pan PET/CT imaging is safe and may be valuable in discriminating incidental findings identified on 18F-FDG PET/CT from true positive lesions and in localizing metastatic LNs.

Personalized Targeted Therapeutic Strategies against Oral Squamous Cell Carcinoma. An Evidence-Based Review of Literature

Oral squamous cell carcinoma (OSCC) is the most common type of malignant tumor in the head and neck, with a poor prognosis mainly due to recurrence and metastasis. Classical treatment modalities for OSCC like surgery and radiotherapy have difficulties in dealing with metastatic tumors, and together with chemotherapy, they have major problems related to non-specific cell death. Molecular targeted therapies offer solutions to these problems through not only potentially maximizing the anticancer efficacy but also minimizing the treatment-related toxicity. Among them, the receptor-mediated targeted delivery of anticancer therapeutics remains the most promising one. As OSCC exhibits a heterogeneous nature, selecting the appropriate receptors for targeting is the prerequisite. Hence, we reviewed the OSCC-associated receptors previously used in targeted therapy, focused on their biochemical characteristics and expression patterns, and discussed the application potential in personalized targeted therapy of OSCC. We hope that a better comprehension of this subject will help to provide the fundamental information for OSCC personalized therapeutic planning.

Advances in nuclear medicine-based molecular imaging in head and neck squamous cell carcinoma

Head and neck squamous cell carcinomas (HNSCCs) are often aggressive, making advanced disease very difficult to treat using contemporary modalities, such as surgery, radiation therapy, and chemotherapy. However, targeted therapy, e.g., cetuximab, an epidermal growth factor receptor inhibitor, has demonstrated survival benefit in HNSCC patients with locoregional failure or distant metastasis. Molecular imaging aims at various biomarkers used in targeted therapy, and nuclear medicine-based molecular imaging is a real-time and non-invasive modality with the potential to identify tumor in an earlier and more treatable stage, before anatomic-based imaging reveals diseases. The objective of this comprehensive review is to summarize recent advances in nuclear medicine-based molecular imaging for HNSCC focusing on several commonly radiolabeled biomarkers. The preclinical and clinical applications of these candidate imaging strategies are divided into three categories: those targeting tumor cells, tumor microenvironment, and tumor angiogenesis. This review endeavors to expand the knowledge of molecular biology of HNSCC and help realizing diagnostic potential of molecular imaging in clinical nuclear medicine.

Fabrication of tumor targeting rare-earth nanocrystals for real-time NIR-IIb fluorescence imaging-guided breast cancer precise surgery

The near-infrared fluorescence imaging has been integrated into the operating room to guide tumor resection, potentially reducing the positive margin rates in breast-conserving surgery (BCS). Relative to the widely used first near-infrared fluorescence imaging, imaging in the second near-infrared (NIR-II) region possesses higher contrast and deeper tissue penetration, particularly in the NIR-IIb window, offering many new opportunities for imaging-guided BCS. Here, we fabricated the c(RGDfC) functionalized erbium-based rare-earth nanoparticles (ErNPs@cRGD) with superior optical property in NIR-IIb region. Owing to deeper tissue penetration and efficient tumor targeting, ErNPs@cRGD-based NIR-IIb fluorescence imaging achieved enhanced signal-to-background ratios in tumor visualization, which was able to guide more complete tumor resection, identify multiple microtumors and distinguish malignant lesions from normal tissues in various mice models. Based on these, this NIR-IIb imaging strategy for surgical navigation can significantly reduce positive margin rates and improve prognosis, laying a foundation for the clinical resection of breast cancer.

Preliminary Clinical Application of RGD-Containing Peptides as PET Radiotracers for Imaging Tumors

Angiogenesis is a common feature of many physiological processes and pathological conditions. RGD-containing peptides can strongly bind to integrin αvβ3 expressed on endothelial cells in neovessels and several tumor cells with high specificity, making them promising molecular agents for imaging angiogenesis. Although studies of RGD-containing peptides combined with radionuclides, namely, ¹⁸F, ⁶⁴Cu, and ⁶⁸Ga for positron emission tomography (PET) imaging have shown high spatial resolution and accurate quantification of tracer uptake, only a few of these radiotracers have been successfully translated into clinical use. This review summarizes the RGD-based tracers in terms of accumulation in tumors and adjacent tissues, and comparison with traditional ¹⁸F-fluorodeoxyglucose (FDG) imaging. The value of RGD-based tracers for diagnosis, differential diagnosis, tumor subvolume delineation, and therapeutic response prediction is mainly discussed. Very low RGD accumulation, in contrast to high FDG metabolism, was found in normal brain tissue, indicating that RGD-based imaging provides an excellent tumor-to-background ratio for improved brain tumor imaging. However, the intensity of the RGD-based tracers is much higher than FDG in normal liver tissue, which could lead to underestimation of primary or metastatic lesions in liver. In multiple studies, RGD-based imaging successfully realized the diagnosis and differential diagnosis of solid tumors and also the prediction of chemoradiotherapy response, providing complementary rather than similar information relative to FDG imaging. Of most interest, baseline RGD uptake values can not only be used to predict the tumor efficacy of antiangiogenic therapy, but also to monitor the occurrence of adverse events in normal organs. This unique dual predictive value in antiangiogenic therapy may be better than that of FDG-based imaging.

Circ_LPAR3 promotes the progression of oral squamous cell carcinoma (OSCC)

BACKGROUND

circ_LPAR3 is an oncogene in esophageal squamous cell carcinoma. However, its role in oral squamous cell carcinoma (OSCC) is unknown.

PURPOSE

To reveal the functions of circ_LPAR3 in OSCC.

METHODS

Online bioinformatic analysis was performed to disclose the differential expression of circ_LPAR3, VEGFC, AKT1 in OSCC and also the target predictions of miR-513b-5p. Transfection was applied in OSCC cells. RT-qPCR was used to detect the RNA expression and western blot to measure the proteins, VEGFC and phosphor-AKT1 (ser473, p-AKT1). CCK8 kit was used for viability detection and Flow cytometry for apoptosis evaluation. RNA pull-down and luciferase reporter methods were used to validate the binding sites to miR-513b-5p on circ_LPAR3, VEGFC and AKT1. OSCC mice models were established to further unveil the functions of circ_LPAR3 in OSCC in vivo. H&E staining and immunohistochemistry (CD34, VEGFC and p-AKT1) were further applied to analyze the pathological changes in association with circ_LPAR3 downregulation.

RESULTS

circ_LPAR3 was upregulated in OSCC. Its knockdown in cells could decrease cell survival and mobility and in mice model, could inhibit the tumor growth and angiogenesis. Circ_LPAR3 promoted VEGFC and AKT1 activity by sponging miR-513b-5p in OSCC cells.

CONCLUSION

Knockdown of circ_LPAR3 could inhibit the OSCC progression by sponging miR-513b-5p and activating VEGFC and AKT1.

Molecular Imaging of Angiogenesis in Oncology: Current Preclinical and Clinical Status

Angiogenesis is an active process, regulating new vessel growth, and is crucial for the survival and growth of tumours next to other complex factors in the tumour microenvironment. We present possible molecular imaging approaches for tumour vascularisation and vitality, focusing on radiopharmaceuticals (tracers). Molecular imaging in general has become an integrated part of cancer therapy, by bringing relevant insights on tumour angiogenic status. After a structured PubMed search, the resulting publication list was screened for oncology related publications in animals and humans, disregarding any cardiovascular findings. The tracers identified can be subdivided into direct targeting of angiogenesis (i.e., vascular endothelial growth factor, laminin, and fibronectin) and indirect targeting (i.e., glucose metabolism, hypoxia, and matrix metallo-proteases, PSMA). Presenting pre-clinical and clinical data of most tracers proposed in the literature, the indirect targeting agents are not 1:1 correlated with angiogenesis factors but do have a strong prognostic power in a clinical setting, while direct targeting agents show most potential and specificity for assessing tumour vascularisation and vitality. Within the direct agents, the combination of multiple targeting tracers into one agent (multimers) seems most promising. This review demonstrates the present clinical applicability of indirect agents, but also the need for more extensive research in the field of direct targeting of angiogenesis in oncology. Although there is currently no direct tracer that can be singled out, the RGD tracer family seems to show the highest potential therefore we expect one of them to enter the clinical routine.