OC-0395 Ex vivo validation of PET imaging for response based dose-painting of NSCLC

Background. In rheumatoid arthritis, articular inflammation is a hallmark of disease, while the involvement of extra-articular tissues is less well defined. Here, we examined the feasibility of PET imaging with the macrophage tracer [18F]fluoro-PEG-folate, targeting folate receptorβ(FRβ), to monitor systemic inflammatory disease in liver and spleen of arthritic rats before and after methotrexate (MTX) treatment.Methods. [18F]Fluoro-PEG-folate PET scans (60 min) were acquired in saline- and MTX-treated (1 mg/kg, 4x) arthritic rats, followed by tissue resection and radiotracer distribution analysis. Liver and spleen tissues were stained for ED1/ED2-macrophage markers and FRβexpression.Results. [18F]Fluoro-PEG-folate PET and ex vivo tissue distribution studies revealed a significant (p<0.01) 2-fold lower tracer uptake in both liver and spleen of MTX-treated arthritic rats. Consistently, ED1- and ED2-positive macrophages were significantly (p<0.01) decreased in liver (4-fold) and spleen (3-fold) of MTX-treated compared with saline-treated rats. Additionally, FRβ-positive macrophages were also significantly reduced in liver (5-fold,p<0.005) and spleen (3-fold,p<0.01) of MTX- versus saline-treated rats.Conclusions. MTX treatment reduced activated macrophages in liver and spleen, as markers for systemic inflammation in these organs. Macrophage PET imaging with [18F]fluoro-PEG-folate holds promise for detection of systemic inflammation in RA as well as therapy (MTX) response monitoring.

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Investigating CXCR4 expression of tumor cells and the vascular compartment: A multimodal approach

PLoS ONE ◽

10.1371/journal.pone.0260186 ◽

2021 ◽

Vol 16 (11) ◽

pp. e0260186

Author(s):

Marta Braga ◽

Chee Hau Leow ◽

Javier Hernandez Gil ◽

Jin H. Teh ◽

Laurence Carroll ◽

...

Keyword(s):

Pet Imaging ◽

Microvessel Density ◽

Ex Vivo ◽

Cost Effective ◽

Cxcr4 Expression ◽

Attractive Alternative ◽

Tumor Models ◽

Chemokine Receptor 4 ◽

And Control ◽

Vascular Compartment

The C-X-C chemokine receptor 4 (CXCR4) is G protein-coupled receptor that upon binding to its cognate ligand, can lead to tumor progression. Several CXCR4-targeted therapies are currently under investigation, and with it comes the need for imaging agents capable of accurate depiction of CXCR4 for therapeutic stratification and monitoring. PET agents enjoy the most success, but more cost-effective and radiation-free approaches such as ultrasound (US) imaging could represent an attractive alternative. In this work, we developed a targeted microbubble (MB) for imaging of vascular CXCR4 expression in cancer. A CXCR4-targeted MB was developed through incorporation of the T140 peptide into the MB shell. Binding properties of the T140-MB and control, non-targeted MB (NT-MB) were evaluated in MDA-MB-231 cells where CXCR4 expression was knocked-down (via shRNA) through optical imaging, and in the lymphoma tumor models U2932 and SuDHL8 (high and low CXCR4 expression, respectively) by US imaging. PET imaging of [18F]MCFB, a tumor-penetrating CXCR4-targeted small molecule, was used to provide whole-tumor CXCR4 readouts. CXCR4 expression and microvessel density were performed by immunohistochemistry analysis and western blot. T140-MB were formed with similar properties to NT-MB and accumulated sensitively and specifically in cells according to their CXCR4 expression. In NOD SCID mice, T140-MB persisted longer in tumors than NT-MB, indicative of target interaction, but showed no difference between U2932 and SuDHL8. In contrast, PET imaging with [18F]MCFB showed a marked difference in tumor uptake at 40–60 min post-injection between the two tumor models (p<0.05). Ex vivo analysis revealed that the large differences in CXCR4 expression between the two models are not reflected in the vascular compartment, where the MB are restricted; in fact, microvessel density and CXCR4 expression in the vasculature was comparable between U2932 and SuDHL8 tumors. In conclusion, we successfully developed a T140-MB that can be used for imaging CXCR4 expression in the tumor vasculature.

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Designed multifunctional polymeric nanomedicines: long-term biodistribution and tumour accumulation of aptamer-targeted nanomaterials

Chemical Communications ◽

10.1039/c8cc05831h ◽

2018 ◽

Vol 54 (82) ◽

pp. 11538-11541 ◽

Cited By ~ 17

Author(s):

N. L. Fletcher ◽

Z. H. Houston ◽

J. D. Simpson ◽

R. N. Veedu ◽

K. J. Thurecht

Keyword(s):

Polyethylene Glycol ◽

Pet Imaging ◽

Hyperbranched Polymer ◽

Ex Vivo

We report a novel multifunctional hyperbranched polymer based on polyethylene glycol (PEG) as a nanomedicine platform that facilitates longitudinal and quantitative 89Zr-PET imaging, enhancing knowledge of nanomaterial biodistribution and pharmacokinetics/pharmacodynamics both in vivo and ex vivo.

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Abstract 2876: Early Retention and Subsequent Engraftment of Transplanted Progenitor Cells is Improved by Delivery within Collagen Matrix

Circulation ◽

10.1161/circ.118.suppl_18.s_790-b ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Yan Zhang ◽

Marc Lamoureux ◽

Stephanie Thorn ◽

Vincent Chan ◽

Joel Price ◽

...

Keyword(s):

Cell Therapy ◽

Progenitor Cells ◽

Pet Imaging ◽

Ex Vivo ◽

Collagen Matrix ◽

Cell Labeling ◽

Type I ◽

The Matrix ◽

Early Retention

Background: To investigate the mechanisms involved in the potentiation of cell therapy by delivery matrices, we evaluated the retention and engraftment of transplanted human circulating progenitor cells (CPCs) injected in a collagen matrix by using in vivo positron emission tomography (PET) imaging, ex vivo biodistribution, and immunohistochemistry. Methods: CPCs were labeled with 18 F-FDG and injected with or without a collagen type I-based matrix in the ischemic hindlimb muscle (IM) of rats (2x10 6 cells; n=15/group). Localization of cells was acquired by PET imaging (15 min) at 150 min post-injection. In addition, radionuclide biodistribution, immunofluorescence, and immunohistochemical examination of transplanted CPCs were performed at up to 14 days. Results: Cell labeling efficiency was CPC-concentration dependent (r=0.61, p <0.001), but not 18 F-FDG-dose dependent. Labeled CPCs exhibited excellent short-term stability and viability. Persistence of 18 F-FDG radioactivity in cells was markedly greater than non-specific retention in the matrix. Wholebody (WB) PET images revealed better CPC retention in the IM and less non-specific leakage to other tissues when CPCs were delivered within the matrix (IM/WB retention ratio of 43.9±8.2%), compared to cells injected alone (22.3±10.4%; p =0.040) and to 18 F-FDG injected with or without the matrix (9.7±5.5% and 11.0±5.5%, respectively; p <0.005). Radioactivity biodistribution confirmed that accumulation was increased (by 92.5%; p =0.024) in the IM and reduced (by 1.1 to 23.8%; p <0.05) in non-specific tissues when cells were injected within the matrix, compared to cells injected alone. Anti-human mitochondria staining showed increased cell retention in the IM with use of matrices (3.0±2.1%) versus cells only (1.9±0.8%; p =0.048). At 14 days the number of CD31 + transplanted human cells was greater (1.6±0.1%) when injected within the matrix than injected alone (0.7±0.1%; p =0.004). Conclusions: Collagen-based delivery matrices improve the early retention of transplanted CPCs, which in turn favors subsequent cell engraftment in the ischemic tissue. This mechanism conferred by the matrix has potential implications for the optimization of cell therapy at the early stages after cell delivery.

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Quantitative PET imaging of PD-L1 expression in xenograft and syngeneic tumour models using a site-specifically labelled PD-L1 antibody

European Journal of Nuclear Medicine and Molecular Imaging ◽

10.1007/s00259-019-04646-4 ◽

2019 ◽

Vol 47 (5) ◽

pp. 1302-1313 ◽

Cited By ~ 5

Author(s):

Camilla Christensen ◽

Lotte K. Kristensen ◽

Maria Z. Alfsen ◽

Carsten H. Nielsen ◽

Andreas Kjaer

Keyword(s):

Pet Imaging ◽

Predictive Value ◽

Ex Vivo ◽

Response To Therapy ◽

Whole Body ◽

Therapeutic Monitoring ◽

Non Invasive ◽

Tumour Bearing ◽

Quantitative Pet

Abstract Purpose Despite remarkable clinical responses and prolonged survival across several cancers, not all patients benefit from PD-1/PD-L1 immune checkpoint blockade. Accordingly, assessment of tumour PD-L1 expression by immunohistochemistry (IHC) is increasingly applied to guide patient selection, therapeutic monitoring, and improve overall response rates. However, tissue-based methods are invasive and prone to sampling error. We therefore developed a PET radiotracer to specifically detect PD-L1 expression in a non-invasive manner, which could be of diagnostic and predictive value. Methods Anti-PD-L1 (clone 6E11, Genentech) was site-specifically conjugated with DIBO-DFO and radiolabelled with 89Zr (89Zr-DFO-6E11). 89Zr-DFO-6E11 was optimized in vivo by longitudinal PET imaging and dose escalation with excess unlabelled 6E11 in HCC827 tumour-bearing mice. Specificity of 89Zr-DFO-6E11 was evaluated in NSCLC xenografts and syngeneic tumour models with different levels of PD-L1 expression. In vivo imaging data was supported by ex vivo biodistribution, flow cytometry, and IHC. To evaluate the predictive value of 89Zr-DFO-6E11 PET imaging, CT26 tumour-bearing mice were subjected to external radiation therapy (XRT) in combination with PD-L1 blockade. Results 89Zr-DFO-6E11 was successfully labelled with a high radiochemical purity. The HCC827 tumours and lymphoid tissue were identified by 89Zr-DFO-6E11 PET imaging, and co-injection with 6E11 increased the relative tumour uptake and decreased the splenic uptake. 89Zr-DFO-6E11 detected the differences in PD-L1 expression among tumour models as evaluated by ex vivo methods. 89Zr-DFO-6E11 quantified the increase in PD-L1 expression in tumours and spleens of irradiated mice. XRT and anti-PD-L1 therapy effectively inhibited tumour growth in CT26 tumour-bearing mice (p < 0.01), and the maximum 89Zr-DFO-6E11 tumour-to-muscle ratio correlated with response to therapy (p = 0.0252). Conclusion PET imaging with 89Zr-DFO-6E11 is an attractive approach for specific, non-invasive, whole-body visualization of PD-L1 expression. PD-L1 expression can be modulated by radiotherapy regimens and 89Zr-DFO-6E11 PET is able to monitor these changes and predict the response to therapy in an immunocompetent tumour model.

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Brain mGluR5 in mice with amyloid beta pathology studied with in vivo [11C]ABP688 PET imaging and ex vivo immunoblotting

Neuropharmacology ◽

10.1016/j.neuropharm.2016.10.009 ◽

2017 ◽

Vol 113 ◽

pp. 293-300 ◽

Cited By ~ 14

Author(s):

Xiaotian T. Fang ◽

Jonas Eriksson ◽

Gunnar Antoni ◽

Ulrika Yngve ◽

Linda Cato ◽

...

Keyword(s):

Amyloid Beta ◽

Pet Imaging ◽

Ex Vivo

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Improved Detection of Molecular Markers of Atherosclerotic Plaques Using Sub-Millimeter PET Imaging

Molecules ◽

10.3390/molecules25081838 ◽

2020 ◽

Vol 25 (8) ◽

pp. 1838 ◽

Cited By ~ 1

Author(s):

Jessica Bridoux ◽

Sara Neyt ◽

Pieterjan Debie ◽

Benedicte Descamps ◽

Nick Devoogdt ◽

...

Keyword(s):

Pet Imaging ◽

Ex Vivo ◽

High Sensitivity ◽

Radiochemical Yield ◽

Control Group ◽

Complexing Agent ◽

Atherosclerotic Plaques ◽

Atherosclerotic Lesions ◽

Pet Ct

Since atherosclerotic plaques are small and sparse, their non-invasive detection via PET imaging requires both highly specific radiotracers as well as imaging systems with high sensitivity and resolution. This study aimed to assess the targeting and biodistribution of a novel fluorine-18 anti-VCAM-1 Nanobody (Nb), and to investigate whether sub-millimetre resolution PET imaging could improve detectability of plaques in mice. The anti-VCAM-1 Nb functionalised with the novel restrained complexing agent (RESCA) chelator was labelled with [18F]AlF with a high radiochemical yield (>75%) and radiochemical purity (>99%). Subsequently, [18F]AlF(RESCA)-cAbVCAM1-5 was injected in ApoE−/− mice, or co-injected with excess of unlabelled Nb (control group). Mice were imaged sequentially using a cross-over design on two different commercially available PET/CT systems and finally sacrificed for ex vivo analysis. Both the PET/CT images and ex vivo data showed specific uptake of [18F]AlF(RESCA)-cAbVCAM1-5 in atherosclerotic lesions. Non-specific bone uptake was also noticeable, most probably due to in vivo defluorination. Image analysis yielded higher target-to-heart and target-to-brain ratios with the β-CUBE (MOLECUBES) PET scanner, demonstrating that preclinical detection of atherosclerotic lesions could be improved using the latest PET technology.

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A Novel PET Imaging Using64Cu-Labeled Monoclonal Antibody against Mesothelin Commonly Expressed on Cancer Cells

Journal of Immunology Research ◽

10.1155/2015/268172 ◽

2015 ◽

Vol 2015 ◽

pp. 1-15 ◽

Cited By ~ 15

Author(s):

Kazuko Kobayashi ◽

Takanori Sasaki ◽

Fumiaki Takenaka ◽

Hiromasa Yakushiji ◽

Yoshihiro Fujii ◽

...

Keyword(s):

Monoclonal Antibody ◽

Cancer Cells ◽

Pet Imaging ◽

Ex Vivo ◽

Chelating Agent ◽

Pancreatic Cancer Cells ◽

Positron Emission ◽

Wide Range

Mesothelin (MSLN) is a 40-kDa cell differentiation-associated glycoprotein appearing with carcinogenesis and is highly expressed in many human cancers, including the majority of pancreatic adenocarcinomas, ovarian cancers, and mesotheliomas, while its expression in normal tissue is limited to mesothelial cells lining the pleura, pericardium, and peritoneum. Clone 11-25 is a murine hybridoma secreting monoclonal antibody (mAb) against human MSLN. In this study, we applied the 11-25 mAb toin vivoimaging to detect MSLN-expressing tumors. Inin vitroandex vivoimmunochemical studies, we demonstrated specificity of 11-25 mAb to membranous MSLN expressed on several pancreatic cancer cells. We showed the accumulation of Alexa Fluor 750-labeled 11-25 mAb in MSLN-expressing tumor xenografts in athymic nude mice. Then, 11-25 mAb was labeled with64Cu via a chelating agent DOTA and was used in bothin vitrocell binding assay andin vivopositron emission tomography (PET) imaging in the tumor-bearing mice. We confirmed that64Cu-labeled 11-25 mAb highly accumulated in MSLN-expressing tumors as compared to MSLN-negative ones. The64Cu-labeled 11-25 mAb is potentially useful as a PET probe capable of being used for wide range of tumors, rather than18F-FDG that occasionally provides nonspecific accumulation into the inflammatory lesions.

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Evaluation of [68Ga]Ga-NODAGA-RGD for PET Imaging of Rat Autoimmune Myocarditis

Frontiers in Medicine ◽

10.3389/fmed.2021.783596 ◽

2021 ◽

Vol 8 ◽

Author(s):

Arghavan Jahandideh ◽

Mia Ståhle ◽

Jenni Virta ◽

Xiang-Guo Li ◽

Heidi Liljenbäck ◽

...

Keyword(s):

Pet Imaging ◽

Ex Vivo ◽

Cell Surface Receptor ◽

Myocardial Inflammation ◽

Autoimmune Myocarditis ◽

Inflammatory Lesions ◽

Pet Tracer ◽

Freund’S Adjuvant ◽

Freund's Adjuvant

The 68Gallium-labeled 1,4,7-triazacyclononane-1-glutaric acid-4,7-diacetic acid conjugated radiolabelled arginine-glycine-aspartic acid peptide ([68Ga]Ga-NODAGA-RGD) is a positron emission tomography (PET) tracer binding to cell surface receptor αvβ3 integrin that is upregulated during angiogenesis and inflammation. We studied whether αvβ3 targeting PET imaging can detect myocardial inflammation in a rat model of autoimmune myocarditis. To induce myocarditis, rats (n = 8) were immunized with porcine cardiac myosin in complete Freund's adjuvant on days 0 and 7. Control rats (n = 8) received Freund's adjuvant alone. On day 21, in vivo PET/CT imaging with [68Ga]Ga-NODAGA-RGD followed by ex vivo autoradiography and immunohistochemistry were carried out. Inflammatory lesions were detected histologically in the myocardium of 7 out of 8 immunized rats. In vivo PET images showed higher [68Ga]Ga-NODAGA-RGD accumulation in the myocardium of rats with inflammation than the non-inflamed myocardium of control rats (SUVmean 0.4 ± 0.1 vs. 0.1 ± 0.02; P = 0.00006). Ex vivo autoradiography and histology confirmed that [68Ga]Ga-NODAGA-RGD uptake co-localized with inflammatory lesions containing αvβ3 integrin-positive capillary-like structures. A non-specific [68Ga]Ga-DOTA-(RGE)2 tracer showed 76% lower uptake than [68Ga]Ga-NODAGA-RGD in the inflamed myocardium. Our results indicate that αvβ3 integrin-targeting [68Ga]Ga-NODAGA-RGD is a potential PET tracer for the specific detection of active inflammatory lesions in autoimmune myocarditis.

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