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Pees A, Vosjan MJWD, Vasdev N, Windhorst AD, Vugts DJ. Fluorine-18 labelled Ruppert-Prakash reagent ([ 18F]Me 3SiCF 3) for the synthesis of 18F-trifluoromethylated compounds. Chem Commun (Camb) 2021; 57:5286-5289. [PMID: 33942818 DOI: 10.1039/d1cc01789f] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
This article describes the first synthesis and application of fluorine-18 labelled Ruppert-Prakash reagent [18F]Me3SiCF3. [18F]Me3SiCF3 was synthesized from [18F]fluoroform with radiochemical yields of 85-95% and radiochemical purities of >95% within 20 minutes. 18F-trifluoromethylated compounds were successfully prepared by reaction of [18F]Me3SiCF3 with benzaldehydes, acetophenones and benzophenones.
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Verfaillie SC, Golla SS, Timmers T, Tuncel H, van der Weijden CW, Schober P, Schuit RC, van der Flier WM, Windhorst AD, Lammertsma AA, van Berckel BN, Boellaard R. Repeatability of parametric methods for [ 18F]florbetapir imaging in Alzheimer's disease and healthy controls: A test-retest study. J Cereb Blood Flow Metab 2021; 41:569-578. [PMID: 32321347 PMCID: PMC7907981 DOI: 10.1177/0271678x20915403] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Accumulation of amyloid beta (Aβ) is one of the pathological hallmarks of Alzheimer's disease (AD), which can be visualized using [18F]florbetapir positron emission tomography (PET). The aim of this study was to evaluate various parametric methods and to assess their test-retest (TRT) reliability. Two 90 min dynamic [18F]florbetapir PET scans, including arterial sampling, were acquired (n = 8 AD patient, n = 8 controls). The following parametric methods were used; (reference:cerebellum); Logan and spectral analysis (SA), receptor parametric mapping (RPM), simplified reference tissue model2 (SRTM2), reference Logan (rLogan) and standardized uptake value ratios (SUVr(50-70)). BPND+1, DVR, VT and SUVr were compared with corresponding estimates (VT or DVR) from the plasma input reversible two tissue compartmental (2T4k_VB) model with corresponding TRT values for 90-scan duration. RPM (r2 = 0.92; slope = 0.91), Logan (r2 = 0.95; slope = 0.84) and rLogan (r2 = 0.94; slope = 0.88), and SRTM2 (r2 = 0.91; slope = 0.83), SA (r2 = 0.91; slope = 0.88), SUVr (r2 = 0.84; slope = 1.16) correlated well with their 2T4k_VB counterparts. RPM (controls: 1%, AD: 3%), rLogan (controls: 1%, AD: 3%) and SUVr(50-70) (controls: 3%, AD: 8%) showed an excellent TRT reliability. In conclusion, most parametric methods showed excellent performance for [18F]florbetapir, but RPM and rLogan seem the methods of choice, combining the highest accuracy and best TRT reliability.
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Coomans EM, Schoonhoven DN, Tuncel H, Verfaillie SCJ, Wolters EE, Boellaard R, Ossenkoppele R, den Braber A, Scheper W, Schober P, Sweeney SP, Ryan JM, Schuit RC, Windhorst AD, Barkhof F, Scheltens P, Golla SSV, Hillebrand A, Gouw AA, van Berckel BNM. In vivo tau pathology is associated with synaptic loss and altered synaptic function. Alzheimers Res Ther 2021; 13:35. [PMID: 33546722 PMCID: PMC7866464 DOI: 10.1186/s13195-021-00772-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 01/11/2021] [Indexed: 01/08/2023]
Abstract
BACKGROUND The mechanism of synaptic loss in Alzheimer's disease is poorly understood and may be associated with tau pathology. In this combined positron emission tomography (PET) and magnetoencephalography (MEG) study, we aimed to investigate spatial associations between regional tau pathology ([18F]flortaucipir PET), synaptic density (synaptic vesicle 2A [11C]UCB-J PET) and synaptic function (MEG) in Alzheimer's disease. METHODS Seven amyloid-positive Alzheimer's disease subjects from the Amsterdam Dementia Cohort underwent dynamic 130-min [18F]flortaucipir PET, dynamic 60-min [11C]UCB-J PET with arterial sampling and 2 × 5-min resting-state MEG measurement. [18F]flortaucipir- and [11C]UCB-J-specific binding (binding potential, BPND) and MEG spectral measures (relative delta, theta and alpha power; broadband power; and peak frequency) were assessed in cortical brain regions of interest. Associations between regional [18F]flortaucipir BPND, [11C]UCB-J BPND and MEG spectral measures were assessed using Spearman correlations and generalized estimating equation models. RESULTS Across subjects, higher regional [18F]flortaucipir uptake was associated with lower [11C]UCB-J uptake. Within subjects, the association between [11C]UCB-J and [18F]flortaucipir depended on within-subject neocortical tau load; negative associations were observed when neocortical tau load was high, gradually changing into opposite patterns with decreasing neocortical tau burden. Both higher [18F]flortaucipir and lower [11C]UCB-J uptake were associated with altered synaptic function, indicative of slowing of oscillatory activity, most pronounced in the occipital lobe. CONCLUSIONS These results indicate that in Alzheimer's disease, tau pathology is closely associated with reduced synaptic density and synaptic dysfunction.
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de Vries BM, Timmers T, Wolters EE, Ossenkoppele R, Verfaillie SCJ, Schuit RC, Scheltens P, van der Flier WM, Windhorst AD, van Berckel BNM, Boellaard R, Golla SSV. Non-invasive Standardised Uptake Value for Verification of the Use of Previously Validated Reference Region for [ 18F]Flortaucipir and [ 18F]Florbetapir Brain PET Studies. Mol Imaging Biol 2021; 23:550-559. [PMID: 33443720 PMCID: PMC8277631 DOI: 10.1007/s11307-020-01572-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 11/20/2020] [Accepted: 12/16/2020] [Indexed: 11/24/2022]
Abstract
Purpose The simplified reference tissue model (SRTM) is commonly applied for the quantification of brain positron emission tomography (PET) studies, particularly because it avoids arterial cannulation. SRTM requires a validated reference region which is obtained by baseline-blocking or displacement studies. Once a reference region is validated, the use should be verified for each new subject. This verification normally requires volume of distribution (VT) of a reference region. However, performing dynamic scanning and arterial sampling is not always possible, specifically in elderly subjects and in advanced disease stages. The aim of this study was to investigate the use of non-invasive standardised uptake value (SUV) approaches, in comparison to VT, as a verification of the previously validated grey matter cerebellum reference region for [18F]flortaucipir and [18F]florbetapir PET imaging in Alzheimer’s disease (AD) patients and controls. Procedures Dynamic 130-min [18F]flortaucipir PET scans obtained from nineteen subjects (10 AD patients) and 90-min [18F]florbetapir dynamic scans obtained from fourteen subjects (8 AD patients) were included. Regional VT’s were estimated for both tracers and were considered the standard verification of the previously validated reference region. Non-invasive SUVs corrected for body weight (SUVBW), lean body mass (SUL), and body surface area (SUVBSA) were obtained by using later time intervals of the dynamic scans. Simulations were also performed to assess the effect of flow and specific binding (BPND) on the SUVs. Results A low SUV corresponded well with a low VT for both [18F]flortaucipir and [18F]florbetapir. Simulation confirmed that SUVs were only slightly affected by flow changes and that increases in SUV were predominantly determined by the presence of specific binding. Conclusions In situations where dynamic scanning and arterial sampling is not possible, a low SUV(80–100 min) for [18F]flortaucipir and a low SUV(50–70 min) for [18F]florbetapir may be used as indication for absence of specific binding in the grey matter cerebellum reference region. Supplementary Information The online version contains supplementary material available at 10.1007/s11307-020-01572-y.
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van Groen BD, Krekels EHJ, Mooij MG, van Duijn E, Vaes WHJ, Windhorst AD, van Rosmalen J, Hartman SJF, Hendrikse NH, Koch BCP, Allegaert K, Tibboel D, Knibbe CAJ, de Wildt SN. The Oral Bioavailability and Metabolism of Midazolam in Stable Critically Ill Children: A Pharmacokinetic Microtracing Study. Clin Pharmacol Ther 2021; 109:140-149. [PMID: 32403162 PMCID: PMC7818442 DOI: 10.1002/cpt.1890] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 04/15/2020] [Indexed: 12/21/2022]
Abstract
Midazolam is metabolized by the developmentally regulated intestinal and hepatic drug-metabolizing enzyme cytochrome P450 (CYP) 3A4/5. It is frequently administered orally to children, yet knowledge is lacking on the oral bioavailability in term neonates up until 1 year of age. Furthermore, the dispositions of the major metabolites 1-OH-midazolam (OHM) and 1-OH-midazolam-glucuronide (OHMG) after oral administration are largely unknown for the entire pediatric age span. We aimed to fill these knowledge gaps with a pediatric [14 C]midazolam microtracer population pharmacokinetic study. Forty-six stable, critically ill children (median age 9.8 (range 0.3-276.4) weeks) received a single oral [14 C]midazolam microtracer (58 (40-67) Bq/kg) when they received a therapeutic continuous intravenous midazolam infusion and had an arterial line in place enabling blood sampling. For midazolam, in a one-compartment model, bodyweight was a significant predictor for clearance (0.98 L/hour) and volume of distribution (8.7 L) (values for a typical individual of 5 kg). The typical oral bioavailability in the population was 66% (range 25-85%). The exposures of OHM and OHMG were highest for the youngest age groups and significantly decreased with postnatal age. The oral bioavailability of midazolam, largely reflective of intestinal and hepatic CYP3A activity, was on average lower than the reported 49-92% for preterm neonates, and higher than the reported 21% for children> 1 year of age and 30% for adults. As midazolam oral bioavailability varied widely, systemic exposure of other CYP3A-substrate drugs after oral dosing in this population may also be unpredictable, with risk of therapy failure or toxicity.
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Visser GWM, Windhorst AD. Synchronizing chemistry, quantum mechanics and radioactivity in a revolutionary renewed atom model. Part 1: the elements where Z is 1–10 (H, He, Li, Be, B, C, N, O, F, Ne). RSC Adv 2021; 11:27978-27991. [PMID: 35480722 PMCID: PMC9038058 DOI: 10.1039/d1ra03529k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/30/2021] [Indexed: 12/02/2022] Open
Abstract
The alliance between the reigning quantum mechanical atom model and chemistry still is a difficult one when it comes to an adequate explanation for e.g. the covalent bond, inversion, chirality, or hydrogen bonds. Overruling Rutherford's extrapolation from gold to hydrogen, an atom model is described that provides improved answers to these phenomena while the hybridization principle and the covalent bond are re-defined by giving neutrons a much more prominent role than they have in the reigning quantum mechanical model. It is postulated that a neutron is not just there to assist the strong force in surpassing the repulsive coulombic forces between the protons in the nucleus, but the neutron is the modus operandi of molecular geometry, and as such plays a part in chemical reactivity, bond length and bond strength. A renewed atom model is described that provides improved answers to unsolved phenomena like inversion, chirality, hydrogen bonds, the hybridization principle and covalent bonds by giving neutrons a much more prominent role.![]()
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Windhorst AD. William C. Eckelman, an icon of radiopharmaceutical sciences. Nucl Med Biol 2021; 92:1. [PMID: 33551046 DOI: 10.1016/j.nucmedbio.2020.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 11/17/2022]
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van Dongen GAMS, Beaino W, Windhorst AD, Zwezerijnen GJC, Oprea-Lager DE, Hendrikse NH, van Kuijk C, Boellaard R, Huisman MC, Vugts DJ. The Role of 89Zr-Immuno-PET in Navigating and Derisking the Development of Biopharmaceuticals. J Nucl Med 2020; 62:438-445. [PMID: 33277395 DOI: 10.2967/jnumed.119.239558] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/01/2020] [Indexed: 12/18/2022] Open
Abstract
The identification of molecular drivers of disease and the compelling rise of biotherapeutics have impacted clinical care but have also come with challenges. Such therapeutics include peptides, monoclonal antibodies, antibody fragments and nontraditional binding scaffolds, activatable antibodies, bispecific antibodies, immunocytokines, antibody-drug conjugates, enzymes, polynucleotides, and therapeutic cells, as well as alternative drug carriers such as nanoparticles. Drug development is expensive, attrition rates are high, and efficacy rates are lower than desired. Almost all these drugs, which in general have a long residence time in the body, can stably be labeled with 89Zr for whole-body PET imaging and quantification. Although not restricted to monoclonal antibodies, this approach is called 89Zr-immuno-PET. This review summarizes the state of the art of the technical aspects of 89Zr-immuno-PET and illustrates why it has potential for steering the design, development, and application of biologic drugs. Appealing showcases are discussed to illustrate what can be learned with this emerging technology during preclinical and especially clinical studies about biologic drug formats and disease targets. In addition, an overview of ongoing and completed clinical trials is provided. Although 89Zr-immuno-PET is a young tool in drug development, its application is rapidly expanding, with first clinical experiences giving insight on why certain drug-target combinations might have better perspectives than others.
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D'Huyvetter M, Vos JD, Caveliers V, Vaneycken I, Heemskerk J, Duhoux FP, Fontaine C, Vanhoeij M, Windhorst AD, Aa FVD, Hendrikse NH, Eersels JLE, Everaert H, Gykiere P, Devoogdt N, Raes G, Lahoutte T, Keyaerts M. Phase I Trial of 131I-GMIB-Anti-HER2-VHH1, a New Promising Candidate for HER2-Targeted Radionuclide Therapy in Breast Cancer Patients. J Nucl Med 2020; 62:1097-1105. [PMID: 33277400 DOI: 10.2967/jnumed.120.255679] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 11/11/2020] [Indexed: 11/16/2022] Open
Abstract
131I-GMIB-anti-human epidermal growth factor receptor type 2 (HER2)-VHH1 is a targeted radionuclide theranostic agent directed at HER2-expressing cancers. VHH1 is a single-domain antibody covalently linked to therapeutic 131I via the linker N-succinimidyl 4-guanidino-methyl-3-iodobenzoate (SGMIB). The phase I study was aimed at evaluating the safety, biodistribution, radiation dosimetry, and tumor-imaging potential of 131I-GMIB-anti-HER2-VHH1 in healthy volunteers and breast cancer patients. Methods: In a first cohort, 6 healthy volunteers were included. The biodistribution of 131I-GMIB-anti-HER2-VHH1 was assessed using whole-body (anterior and posterior) planar images obtained at 40 min and at 2, 4, 24, and 72 h after intravenously administered (38 ± 9 MBq) 131I-GMIB-anti-HER2-VHH1. Imaging data were analyzed using OLINDA/EXM software to determine the dosimetry. Blood and urine samples were obtained over 72 h. In the second cohort, 3 patients with metastatic HER2-positive breast cancer were included. Planar whole-body imaging was performed at 2 and 24 h after injection. Additional SPECT/CT images were obtained after the whole-body images at 2 and 24 h if there was relevant uptake in known cancer lesions. Results: No drug-related adverse events were observed throughout the study. The biologic half-life of 131I-GMIB-anti-HER2-VHH1 in healthy subjects was about 8 h. After intravenous administration, the compound was eliminated from the blood with a 2.5-h half-life. The drug was eliminated primarily via the kidneys. The drug was stable in circulation, and there was no increased accumulation in the thyroid or stomach. The absorbed dose to the kidneys was 1.54 ± 0.25 mGy/MBq, and to bone marrow it was 0.03 ± 0.01 mGy/MBq. SPECT/CT imaging in patients with advanced breast cancer showed focal uptake of 131I-GMIB-anti-HER2-VHH1 in metastatic lesions. Conclusion : Because of its favorable toxicity profile and its uptake in HER2-positive lesions, this radiopharmaceutical can offer new therapeutic options to patients who have progressed on trastuzumab, pertuzumab, or trastuzmab emtansine, given its difference in mode-of-action. A dose escalation is planned in a subsequent phase I/II study to assess the therapeutic window of this compound (NCT04467515).
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Verfaillie SC, Visser D, Wolters EE, Coomans EM, Timmers T, Tuncel H, Boellaard R, Golla SS, Windhorst AD, Scheltens P, van Der Flier W, Ossenkoppele R, Van Berckel BN. Early‐onset Alzheimer’s disease is related to differential spatial patterns of tau pathology and cognitive impairment. Alzheimers Dement 2020. [DOI: 10.1002/alz.042041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Coomans EM, Schoonhoven DN, Tuncel H, Verfaillie SC, Wolters EE, Boellaard R, Ossenkoppele R, Scheper W, Schober P, Sweeney SP, Ryan JM, Schuit RC, Windhorst AD, Barkhof F, Scheltens P, Golla SS, Arjan H, Gouw AA, Van Berckel BN. Regional tau pathology is associated with loss of synapses and reduced synaptic activity: A combined [
18
F]flortaucipir, [
11
C]UCB‐J and magnetoencephalography study. Alzheimers Dement 2020. [DOI: 10.1002/alz.045806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Wolters EE, van de Beek M, Ossenkoppele R, Verfaillie SC, Coomans EM, Timmers T, Visser D, Tuncel H, Golla SS, Windhorst AD, Scheltens P, van Der Flier W, Lemstra AW, Van Berckel BN. Tau pathology, relative cerebral flow and cognition in dementia with Lewy bodies. Alzheimers Dement 2020. [DOI: 10.1002/alz.041048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Coomans EM, Tomassen J, Wolters EE, Golla SS, den Hollander M, Verfaillie SC, Collij L, Windhorst AD, Boellaard R, Barkhof F, Ossenkoppele R, de Geus EJ, Scheltens P, Visser PJ, Van Berckel BN, den Braber A. Regional distribution of tau pathology in cognitively unimpaired, genetically identical twins. Alzheimers Dement 2020. [DOI: 10.1002/alz.045876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Wolters EE, van de Beek M, Ossenkoppele R, Golla SSV, Verfaillie SCJ, Coomans EM, Timmers T, Visser D, Tuncel H, Barkhof F, Boellaard R, Windhorst AD, van der Flier WM, Scheltens P, Lemstra AW, van Berckel BNM. Tau PET and relative cerebral blood flow in dementia with Lewy bodies: A PET study. Neuroimage Clin 2020; 28:102504. [PMID: 33395993 PMCID: PMC7714680 DOI: 10.1016/j.nicl.2020.102504] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/08/2020] [Accepted: 11/10/2020] [Indexed: 02/07/2023]
Abstract
PURPOSE Alpha-synuclein often co-occurs with Alzheimer's disease (AD) pathology in Dementia with Lewy Bodies (DLB). From a dynamic [18F]flortaucipir PET scan we derived measures of both tau binding and relative cerebral blood flow (rCBF). We tested whether regional tau binding or rCBF differed between DLB patients and AD patients and controls and examined their association with clinical characteristics of DLB. METHODS Eighteen patients with probable DLB, 65 AD patients and 50 controls underwent a dynamic 130-minute [18F]flortaucipir PET scan. DLB patients with positive biomarkers for AD based on cerebrospinal fluid or amyloid PET were considered as DLB with AD pathology (DLB-AD+). Receptor parametric mapping (cerebellar gray matter reference region) was used to extract regional binding potential (BPND) and R1, reflecting (AD-specific) tau pathology and rCBF, respectively. First, we performed regional comparisons of [18F]flortaucipir BPND and R1 between diagnostic groups. In DLB patients only, we performed regression analyses between regional [18F]flortaucipir BPND, R1 and performance on ten neuropsychological tests. RESULTS Regional [18F]flortaucipir BPND in DLB was comparable with tau binding in controls (p > 0.05). Subtle higher tau binding was observed in DLB-AD+ compared to DLB-AD- in the medial temporal and parietal lobe (both p < 0.05). Occipital and lateral parietal R1 was lower in DLB compared to AD and controls (all p < 0.01). Lower frontal R1 was associated with impaired performance on digit span forward (standardized beta, stβ = 0.72) and category fluency (stβ = 0.69) tests. Lower parietal R1 was related to lower delayed (stβ = 0.50) and immediate (stβ = 0.48) recall, VOSP number location (stβ = 0.70) and fragmented letters (stβ = 0.59) scores. Lower occipital R1 was associated to worse performance on VOSP fragmented letters (stβ = 0.61), all p < 0.05. CONCLUSION The amount of tau binding in DLB was minimal and did not differ from controls. However, there were DLB-specific occipital and lateral parietal relative cerebral blood flow reductions compared to both controls and AD patients. Regional rCBF, but not tau binding, was related to cognitive impairment. This indicates that assessment of rCBF may give more insight into disease mechanisms in DLB than tau PET.
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Reimand J, Groot C, Teunissen CE, Windhorst AD, Boellaard R, Barkhof F, Nazarenko S, van der Flier WM, van Berckel BNM, Scheltens P, Ossenkoppele R, Bouwman F. Why Is Amyloid-β PET Requested After Performing CSF Biomarkers? J Alzheimers Dis 2020; 73:559-569. [PMID: 31796674 PMCID: PMC7081099 DOI: 10.3233/jad-190836] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Amyloid-β positron emission tomography (PET) and cerebrospinal fluid (CSF) Aβ42 are considered interchangeable for clinical diagnosis of Alzheimer's disease. OBJECTIVE To explore the clinical reasoning for requesting additional amyloid-β PET after performing CSF biomarkers. METHODS We retrospectively identified 72 memory clinic patients who underwent amyloid-β PET after CSF biomarkers analysis for clinical diagnostic evaluation between 2011 and 2019. We performed patient chart reviews to identify factors which led to additional amyloid-β PET. Additionally, we assessed accordance with appropriate-use-criteria (AUC) for amyloid-β PET. RESULTS Mean patient age was 62.0 (SD = 8.1) and mean Mini-Mental State Exam score was 23.6 (SD = 3.8). CSF analysis conflicting with the clinical diagnosis was the most frequent reason for requesting an amyloid-β PET scan (n = 53, 74%), followed by incongruent MRI (n = 16, 22%), unusual clinical presentation (n = 11, 15%) and young age (n = 8, 11%). An amyloid-β PET scan was rarely (n = 5, 7%) requested in patients with a CSF Aβ+/tau+ status. Fifteen (47%) patients with a post-PET diagnosis of AD had a predominantly non-amnestic presentation. In n = 11 (15%) cases, the reason that the clinician requested amyloid-β was not covered by AUC. This happened most often (n = 7) when previous CSF analysis did not support current clinical diagnosis, which led to requesting amyloid-β PET. CONCLUSION In this single-center study, the main reason for requesting an amyloid-β PET scan after performing CSF biomarkers was the occurrence of a mismatch between the primary clinical diagnosis and CSF Aβ/tau results.
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Beaino W, Janssen B, Kooijman E, Vos R, Schuit RC, O'Brien-Brown J, Kassiou M, van Het Hof B, Vugts DJ, de Vries HE, Windhorst AD. PET imaging of P2X 7R in the experimental autoimmune encephalomyelitis model of multiple sclerosis using [ 11C]SMW139. J Neuroinflammation 2020; 17:300. [PMID: 33054803 PMCID: PMC7556947 DOI: 10.1186/s12974-020-01962-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 09/23/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Non-invasive imaging of the activation status of microglia and the ability to identify a pro- or anti-inflammatory environment can provide valuable insights not only into pathogenesis of neuro-inflammatory and neurodegenerative diseases but also the monitoring of the efficacy of immunomodulatory therapies. P2X7R is highly expressed on pro-inflammatory microglia and [11C]SMW139, a specific P2X7R tracer for positron emission tomography imaging, showed good pharmacokinetics, stability, and brain permeability in vivo. Our objective was to evaluate the potential of [11C]SMW139 for PET imaging of neuroinflammation in vivo in the experimental autoimmune encephalomyelitis (EAE) model. METHODS We induced EAE in Lewis rats by immunization with MBP 69-88 in complete Freund's adjuvant (CFA). We determined the affinity of [11C]SMW139 to human and rat P2X7R using saturation binding assay. Using this tracer, PET imaging was performed at the peak of disease and in the recovery phase. In vivo blocking experiments were conducted to validate the specific brain uptake of the tracer. Immunohistochemistry staining and autoradiography were performed to evaluate the level of neuroinflammation and validate the specific binding of [11C]SMW139. RESULTS [11C]SMW139 showed good affinity for the rat P2X7R with a Kd of 20.6 ± 1.7 nM. The uptake of [11C]SMW139 was significantly higher in EAE animals at the peak of disease compared to the recovery phase but not in CFA control animals. The amplitude of increase of [11C]SMW139 uptake showed significant positive correlation with clinical scores mainly in the spinal cord (Pearson = 0.75, Spearman = 0.76; p < 0.0001). Treating EAE animals with P2X7R antagonist JNJ-47965567 blocked the uptake of [11C]SMW139 in the spinal cord, cerebellum, and brain stem, demonstrating specific accumulation of the tracer. P-glycoprotein blocking with tariquidar (30 mg/kg) did not affect tracer penetration in the brain showing that [11C]SMW139 is not a Pgp substrate. CONCLUSION Our data shows that [11C]SMW139 is a promising PET tracer for imaging neuroinflammation and evaluating the dynamics of pro-inflammatory microglia in the brain. This can provide crucial insights into the role of microglia in disease progression and enables the development of novel treatment strategies aimed at modulating the immune response in order to promote neuroprotection.
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Colclough N, Chen K, Johnström P, Strittmatter N, Yan Y, Wrigley GL, Schou M, Goodwin R, Varnäs K, Adua SJ, Zhao M, Nguyen DX, Maglennon G, Barton P, Atkinson J, Zhang L, Janefeldt A, Wilson J, Smith A, Takano A, Arakawa R, Kondrashov M, Malmquist J, Revunov E, Vazquez-Romero A, Moein MM, Windhorst AD, Karp NA, Finlay MRV, Ward RA, Yates JW, Smith PD, Farde L, Cheng Z, Cross DA. Preclinical Comparison of the Blood–brain barrier Permeability of Osimertinib with Other EGFR TKIs. Clin Cancer Res 2020; 27:189-201. [DOI: 10.1158/1078-0432.ccr-19-1871] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 06/18/2020] [Accepted: 09/29/2020] [Indexed: 11/16/2022]
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Chomet M, Schreurs M, Bolijn MJ, Verlaan M, Beaino W, Brown K, Poot AJ, Windhorst AD, Gill H, Marik J, Williams S, Cowell J, Gasser G, Mindt TL, van Dongen GAMS, Vugts DJ. Head-to-head comparison of DFO* and DFO chelators: selection of the best candidate for clinical 89Zr-immuno-PET. Eur J Nucl Med Mol Imaging 2020; 48:694-707. [PMID: 32889615 PMCID: PMC8036225 DOI: 10.1007/s00259-020-05002-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 08/13/2020] [Indexed: 12/19/2022]
Abstract
Purpose Almost all radiolabellings of antibodies with 89Zr currently employ the hexadentate chelator desferrioxamine (DFO). However, DFO can lead to unwanted uptake of 89Zr in bones due to instability of the resulting metal complex. DFO*-NCS and the squaramide ester of DFO, DFOSq, are novel analogues that gave more stable 89Zr complexes than DFO in pilot experiments. Here, we directly compare these linker-chelator systems to identify optimal immuno-PET reagents. Methods Cetuximab, trastuzumab and B12 (non-binding control antibody) were labelled with 89Zr via DFO*-NCS, DFOSq, DFO-NCS or DFO*Sq. Stability in vitro was compared at 37 °C in serum (7 days), in formulation solution (24 h ± chelator challenges) and in vivo with N87 and A431 tumour-bearing mice. Finally, to demonstrate the practical benefit of more stable complexation for the accurate detection of bone metastases, [89Zr]Zr-DFO*-NCS and [89Zr]Zr-DFO-NCS-labelled trastuzumab and B12 were evaluated in a bone metastasis mouse model where BT-474 breast cancer cells were injected intratibially. Results [89Zr]Zr-DFO*-NCS-trastuzumab and [89Zr]Zr-DFO*Sq-trastuzumab showed excellent stability in vitro, superior to their [89Zr]Zr-DFO counterparts under all conditions. While tumour uptake was similar for all conjugates, bone uptake was lower for DFO* conjugates. Lower bone uptake for DFO* conjugates was confirmed using a second xenograft model: A431 combined with cetuximab. Finally, in the intratibial BT-474 bone metastasis model, the DFO* conjugates provided superior detection of tumour-specific signal over the DFO conjugates. Conclusion DFO*-mAb conjugates provide lower bone uptake than their DFO analogues; thus, DFO* is a superior candidate for preclinical and clinical 89Zr-immuno-PET. Electronic supplementary material The online version of this article (10.1007/s00259-020-05002-7) contains supplementary material, which is available to authorized users.
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Patruno I, Thompson D, Dall'Angelo S, Windhorst AD, Vugts DJ, Poot AJ, Mody N, Zanda M. Design, Synthesis, Radiosynthesis and Biological Evaluation of Fenretinide Analogues as Anticancer and Metabolic Syndrome-Preventive Agents. ChemMedChem 2020; 15:1579-1590. [PMID: 32497314 DOI: 10.1002/cmdc.202000143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/21/2020] [Indexed: 12/31/2022]
Abstract
Fenretinide (4-HPR) is a synthetic derivative of all-trans-retinoic acid (ATRA) characterised by improved therapeutic properties and toxicological profile relative to ATRA. 4-HPR has been mostly investigated as an anti-cancer agent, but recent studies showed its promising therapeutic potential for preventing metabolic syndrome. Several biological targets are involved in 4-HPR's activity, leading to the potential use of this molecule for treating different pathologies. However, although 4-HPR displays quite well-understood multitarget promiscuity with regards to pharmacology, interpreting its precise physiological role remains challenging. In addition, despite promising results in vitro, the clinical efficacy of 4-HPR as a chemotherapeutic agent has not been satisfactory so far. Herein, we describe the preparation of a library of 4-HPR analogues, followed by the biological evaluation of their anti-cancer and anti-obesity/diabetic properties. The click-type analogue 3 b showed good capacity to reduce the amount of lipid accumulation in 3T3-L1 adipocytes during differentiation. Furthermore, it showed an IC50 of 0.53±0.8 μM in cell viability tests on breast cancer cell line MCF-7, together with a good selectivity (SI=121) over noncancerous HEK293 cells. Thus, 3 b was selected as a potential PET tracer to study retinoids in vivo, and the radiosynthesis of [18 F]3b was successfully developed. Unfortunately, the stability of [18 F]3b turned out to be insufficient to pursue imaging studies.
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Longo B, Zanato C, Piras M, Dall'Angelo S, Windhorst AD, Vugts DJ, Baldassarre M, Zanda M. Design, Synthesis, Conjugation, and Reactivity of Novel trans,trans-1,5-Cyclooctadiene-Derived Bioorthogonal Linkers. Bioconjug Chem 2020; 31:2201-2210. [PMID: 32786505 DOI: 10.1021/acs.bioconjchem.0c00375] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The tetrazine/trans-cyclooctene (TCO) inverse electron-demand Diels-Alder (IEDDA) reaction is the fastest bioorthogonal "click" ligation process reported to date. In this context, TCO reagents have found widespread applications; however, their availability and structural diversity is still somewhat limited due to challenges connected with their synthesis and structural modification. To address this issue, we developed a novel strategy for the conjugation of TCO derivatives to a biomolecule, which allows for the creation of greater structural diversity from a single precursor molecule, i.e., trans,trans-1,5-cyclooctadiene [(E,E)-COD] 1, whose preparation requires standard laboratory equipment and readily available reagents. This two-step strategy relies on the use of new bifunctional TCO linkers (5a-11a) for IEDDA reactions, which can be synthesized via 1,3-dipolar cycloaddition of (E,E)-COD 1 with different azido spacers (5-11) carrying an electrophilic function (NHS-ester, N-succinimidyl carbonate, p-nitrophenyl-carbonate, maleimide) in the ω-position. Following bioconjugation of these electrophilic linkers to the nucleophilic residue (cysteine or lysine) of a protein (step 1), the resulting TCO-decorated constructs can be subjected to a IEDDA reaction with tetrazines functionalized with fluorescent or near-infrared (NIR) tags (step 2). We successfully used this strategy to label bovine serum albumin with the TCO linker 8a and subsequently reacted it in a cell lysate with the fluorescein-isothiocyanate (FITC)-derived tetrazine 12. The same strategy was then used to label the bacterial wall of Gram-positive Staphylococcus aureus, showing the potential of these linkers for live-cell imaging. Finally, we determined the impact of structural differences of the linkers upon the stability of the bioorthogonal constructs. The compounds for stability studies were prepared by conjugation of TCO linkers 6a, 8a, and 10a to mAbs, such as Rituximab and Obinutuzumab, and subsequent labeling with a reactive Cy3-functionalized tetrazine.
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Visser D, Wolters EE, Verfaillie SCJ, Coomans EM, Timmers T, Tuncel H, Reimand J, Boellaard R, Windhorst AD, Scheltens P, van der Flier WM, Ossenkoppele R, van Berckel BNM. Tau pathology and relative cerebral blood flow are independently associated with cognition in Alzheimer's disease. Eur J Nucl Med Mol Imaging 2020; 47:3165-3175. [PMID: 32462397 PMCID: PMC7680306 DOI: 10.1007/s00259-020-04831-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 04/16/2020] [Indexed: 12/18/2022]
Abstract
Purpose We aimed to investigate associations between tau pathology and relative cerebral blood flow (rCBF), and their relationship with cognition in Alzheimer’s disease (AD), by using a single dynamic [18F]flortaucipir positron emission tomography (PET) scan. Methods Seventy-one subjects with AD (66 ± 8 years, mini-mental state examination (MMSE) 23 ± 4) underwent a dynamic 130-min [18F]flortaucipir PET scan. Cognitive assessment consisted of composite scores of four cognitive domains. For tau pathology and rCBF, receptor parametric mapping (cerebellar gray matter reference region) was used to create uncorrected and partial volume-corrected parametric images of non-displaceable binding potential (BPND) and R1, respectively. (Voxel-wise) linear regressions were used to investigate associations between BPND and/or R1 and cognition. Results Higher [18F]flortaucipir BPND was associated with lower R1 in the lateral temporal, parietal and occipital regions. Higher medial temporal BPND was associated with worse memory, and higher lateral temporal BPND with worse executive functioning and language. Higher parietal BPND was associated with worse executive functioning, language and attention, and higher occipital BPND with lower cognitive scores across all domains. Higher frontal BPND was associated with worse executive function and attention. For [18F]flortaucipir R1, lower values in the lateral temporal and parietal ROIs were associated with worse executive functioning, language and attention, and lower occipital R1 with lower language and attention scores. When [18F]flortaucipir BPND and R1 were modelled simultaneously, associations between lower R1 in the lateral temporal ROI and worse attention remained, as well as for lower parietal R1 and worse executive functioning and attention. Conclusion Tau pathology was associated with locally reduced rCBF. Tau pathology and low rCBF were both independently associated with worse cognitive performance. For tau pathology, these associations spanned widespread neocortex, while for rCBF, independent associations were restricted to lateral temporal and parietal regions and the executive functioning and attention domains. These findings indicate that each biomarker may independently contribute to cognitive impairment in AD. Electronic supplementary material The online version of this article (10.1007/s00259-020-04831-w) contains supplementary material, which is available to authorized users.
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van der Aart J, Yaqub M, Kooijman EJM, Bakker J, Langermans JAM, Schuit RC, Hofman MBM, Christiaans JAM, Lammertsma AA, Windhorst AD, van Berckel BNM. Evaluation of the Novel PET Tracer [ 11C]HACH242 for Imaging the GluN2B NMDA Receptor in Non-Human Primates. Mol Imaging Biol 2020; 21:676-685. [PMID: 30306318 DOI: 10.1007/s11307-018-1284-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
PURPOSE There are currently no positron emission tomography (PET) radiotracers for the GluN2B (NR2B) binding sites of brain N-methyl-D-aspartate (NMDA) receptors. In rats, the GluN2B antagonist Ro25-6981 reduced the binding of N-((5-(4-fluoro-2-[11C]methoxyphenyl)pyridin-3-yl)methyl)cyclopentanamin ([11C]HACH242). This paper reports the evaluation of [11C]HACH242 PET in non-human primates at baseline and following administration of the GluN2B negative allosteric modulator radiprodil. PROCEDURES Eight 90-min dynamic [11C]HACH242 PET scans were acquired in three male anaesthetised rhesus monkeys, including a retest session of subject 1, at baseline and 10 min after intravenous 10 mg/kg radiprodil. Standardised uptake values (SUV) were calculated for 9 brain regions. Arterial blood samples were taken at six timepoints to characterise pharmacokinetics in blood and plasma. Reliable input functions for kinetic modelling could not be generated due to variability in the whole-blood radioactivity measurements. RESULTS [11C]HACH242 entered the brain and displayed fairly uniform uptake. The mean (± standard deviation, SD) Tmax was 17 ± 7 min in baseline scans and 24 ± 15 min in radiprodil scans. The rate of radioligand metabolism in plasma (primarily to polar metabolites) was high, with mean parent fractions of 26 ± 10 % at 20 min and 8 ± 5 % at 85 min. Radiprodil increased [11C]HACH242 whole-brain SUV in the last PET frame by 25 %, 1 %, 3 and 17 % for subjects 1, 2, 3 and retest of subject 1, respectively. The mean brain to plasma ratio was 5.4 ± 2.6, and increased by 39 to 110 % in the radiprodil condition, partly due to lower parent plasma radioactivity of -11 to -56 %. CONCLUSIONS The present results show that [11C]HACH242 has a suitable kinetic profile in the brain and low accumulation of lipophilic radiometabolites. Radiprodil did not consistently change [11C]HACH242 brain uptake. These findings may be explained by variations in cerebral blood flow, a low fraction of specifically bound tracer, or interactions with endogenous NMDA receptor ligands at the binding site. Further experiments of ligand interactions are necessary to facilitate the development of radiotracers for in vivo imaging of the ionotropic NMDA receptor.
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Wolters EE, Ossenkoppele R, Verfaillie SCJ, Coomans EM, Timmers T, Visser D, Tuncel H, Golla SSV, Windhorst AD, Boellaard R, van der Flier WM, Teunissen CE, Scheltens P, van Berckel BNM. Regional [ 18F]flortaucipir PET is more closely associated with disease severity than CSF p-tau in Alzheimer's disease. Eur J Nucl Med Mol Imaging 2020; 47:2866-2878. [PMID: 32291510 PMCID: PMC7567681 DOI: 10.1007/s00259-020-04758-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/04/2020] [Indexed: 12/15/2022]
Abstract
Purpose In vivo Alzheimer’s disease (AD) biomarkers for tau pathology are cerebrospinal fluid (CSF) phosphorylated tau (p-tau) and [18F]flortaucipir positron emission tomography (PET). Our aim was to assess associations between CSF p-tau with [18F]flortaucipir PET and the associations of both tau biomarkers with cognition and atrophy. Methods We included 78 amyloid positive cognitively impaired patients (clinical diagnoses mild cognitive impairment (MCI, n = 8) and AD dementia (n = 45) and 25 cognitively normal subjects with subjective cognitive decline (SCD) (40% amyloid-positive)). Dynamic 130 min [18F]flortaucipir PET scans were acquired to generate binding potential (BPND) images using receptor parametric mapping and standardized uptake values ratios of 80–100 min (SUVr80-100min) post injection. We obtained regional BPND and SUVr from entorhinal, limbic, and neocortical regions-of-interest (ROIs), closely aligning to the neuropathological tau staging schemes. Cognition was assessed using MMSE and composite scores of four cognitive domains, and atrophy was measured using gray matter volume covering the major brain lobes. First, we used linear regressions to investigate associations between CSF p-tau (independent variable) and tau PET (dependent variable). Second, we used linear regressions to investigate associations between CSF p-tau, tau PET (separate independent variables, model 1), and cognition (dependent variable). We then assessed the independent effects of CSF p-tau and tau PET on cognition by simultaneously adding the other tau biomarker as a predictor (model 2). Finally, we performed the same procedure for model 1 and 2, but replaced cognition with atrophy. Models were adjusted for age, sex, time lag between assessments, education (cognition only), and total intracranial volume (atrophy only). Results Higher [18F]flortaucipir BPND was associated with higher CSF p-tau (range of standardized betas (sβ) across ROIs, 0.43–0.46; all p < 0.01). [18F]flortaucipir BPND was more strongly associated with cognition and atrophy than CSF p-tau. When [18F]flortaucipir BPND and CSF p-tau were entered simultaneously, [18F]flortaucipir BPND (range sβ = − 0.20 to – 0.57, all p < 0.05) was strongly associated with multiple cognitive domains and atrophy regions. SUVr showed comparable results to BPND. Conclusion Regional [18F]flortaucipir BPND correlated stronger with cognition and neurodegeneration than CSF p-tau, suggesting that tau PET more accurately reflects disease severity in AD. Electronic supplementary material The online version of this article (10.1007/s00259-020-04758-2) contains supplementary material, which is available to authorized users.
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Pees A, Windhorst AD, Vosjan MJWD, Tadino V, Vugts DJ. Synthesis of [18
F]Fluoroform with High Molar Activity. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000056] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Huisman MC, Niemeijer ALN, Windhorst AD, Schuit RC, Leung D, Hayes W, Poot A, Bahce I, Radonic T, Oprea-Lager DE, Hoekstra OS, Thunnissen E, Hendrikse NH, Smit EF, de Langen AJ, Boellaard R. Quantification of PD-L1 Expression with 18F-BMS-986192 PET/CT in Patients with Advanced-Stage Non-Small Cell Lung Cancer. J Nucl Med 2020; 61:1455-1460. [PMID: 32060213 DOI: 10.2967/jnumed.119.240895] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 01/29/2020] [Indexed: 11/16/2022] Open
Abstract
The aim of this work was to quantify the uptake of 18F-BMS-986192, a programmed cell death ligand 1 (PD-L1) adnectin PET tracer, in patients with non-small cell lung cancer. To this end, plasma input kinetic modeling of dynamic tumor uptake data with online arterial blood sampling was performed. In addition, the accuracy of simplified uptake metrics such as SUV was investigated. Methods: Data from a study with 18F-BMS-986192 in patients with advanced-stage non-small cell lung cancer eligible for nivolumab treatment were used if a dynamic scan was available and lesions were present in the field of view of the dynamic scan. After injection of 18F-BMS-986192, a 60-min dynamic PET/CT scan was started, followed by a 30-min whole-body PET/CT scan. Continuous arterial and discrete arterial and venous blood sampling were performed to determine a plasma input function. Tumor time-activity curves were fitted by several plasma input kinetic models. Simplified uptake parameters included tumor-to-blood ratio as well as several SUV measures. Results: Twenty-two tumors in 9 patients were analyzed. The arterial plasma input single-tissue reversible compartment model with fitted blood volume fraction seems to be the most preferred model as it best fitted 11 of 18 tumor time-activity curves. The distribution volume (V T ) ranged from 0.4 to 4.8 mL⋅cm-3 Similar values were obtained with an image-derived input function. From the simplified measures, SUV normalized for body weight at 50 and 67 min after injection correlated best with V T , with an R 2 of more than 0.9. Conclusion: A single-tissue reversible model can be used to quantify tumor uptake of the PD-L1 PET tracer 18F-BMS-986192. SUV at 60 min after injection, normalized for body weight, is an accurate simplified parameter for uptake assessment of baseline studies. To assess its predictive value for response evaluation during programmed cell death protein 1 or PD-L1 immune checkpoint inhibition, further validation of SUV against V T based on an image-derived input function is recommended.
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