1
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Zhang L, Wang Y, Homan KT, Gaudette SM, McCluskey AJ, Chan Y, Murphy J, Abdalla M, Nelson CM, Sun VZ, Erickson JE, Knight HL, Clabbers A, Sterman AJS, Mitra S. Imaging the Alternatively Spliced D Domain of Tenascin C in a Preclinical Model of Inflammatory Bowel Disease. Mol Imaging Biol 2023; 25:314-323. [PMID: 35906512 PMCID: PMC10006278 DOI: 10.1007/s11307-022-01758-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/11/2022] [Accepted: 07/12/2022] [Indexed: 11/28/2022]
Abstract
PURPOSE To image colon-expressed alternatively spliced D domain of tenascin C in preclinical colitis models using near infrared (NIR)-labeled targeted molecular imaging agents. PROCEDURES A human IgG1 with nanomolar binding affinity specific to the alternatively spliced D domain of tenascin C was generated. Immunohistochemistry identified disease-specific expression of this extracellular matrix protein in the colon of mice given dextran sulfate sodium in the drinking water. The antibody reagent was labeled with the NIR fluorophore IRDye 800CW via amine chemistry and intravenously dosed to evaluate in vivo targeting specificity. Increasing doses of imaging agent were given to estimate the saturating dose. RESULTS The NIR-labeled proteins successfully targeted colonic lesions in a murine model of colitis. Co-administration of a molar excess competing unlabeled dose reduced normalized uptake in diseased colon by > 70%. Near infrared ex vivo images of colon resected from diseased animals showed saturation at doses exceeding 1 nmol and was confirmed with additional quantitative ex vivo biodistribution. Cellular-level specificity and protein stability were assessed via microscopy. CONCLUSIONS Our imaging data suggest the alternatively spliced D domain of tenascin C is a promising target for delivery-based applications in inflammatory bowel diseases.
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Affiliation(s)
- Liang Zhang
- AbbVie Bioresearch Center, 100 Research Dr, Worcester, MA, 01605, USA.
| | - Yuzhen Wang
- AbbVie Bioresearch Center, 100 Research Dr, Worcester, MA, 01605, USA
| | | | - Stephanie M Gaudette
- Worcester Technical High School, 1 Officer Manny Familia Wy, Worcester, MA, 01605, USA
| | | | - Ying Chan
- AbbVie Bioresearch Center, 100 Research Dr, Worcester, MA, 01605, USA
| | - Joanne Murphy
- AbbVie Bioresearch Center, 100 Research Dr, Worcester, MA, 01605, USA
| | - Mary Abdalla
- AbbVie Bioresearch Center, 100 Research Dr, Worcester, MA, 01605, USA
| | | | - Victor Z Sun
- AbbVie Bioresearch Center, 100 Research Dr, Worcester, MA, 01605, USA
| | - Jamie E Erickson
- AbbVie Bioresearch Center, 100 Research Dr, Worcester, MA, 01605, USA
| | - Heather L Knight
- AbbVie Bioresearch Center, 100 Research Dr, Worcester, MA, 01605, USA
| | - Anca Clabbers
- AbbVie Bioresearch Center, 100 Research Dr, Worcester, MA, 01605, USA
| | | | - Soumya Mitra
- AbbVie Bioresearch Center, 100 Research Dr, Worcester, MA, 01605, USA
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2
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Roberts S, Khera E, Choi C, Navaratna T, Grimm J, Thurber GM, Reiner T. Optoacoustic Imaging of Glucagon-like Peptide-1 Receptor with a Near-Infrared Exendin-4 Analog. J Nucl Med 2021; 62:839-848. [PMID: 33097631 PMCID: PMC8729860 DOI: 10.2967/jnumed.120.252262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 09/18/2020] [Indexed: 11/16/2022] Open
Abstract
Limitations in current imaging tools have long challenged the imaging of small pancreatic islets in animal models. Here, we report the first development and in vivo validation testing of a broad-spectrum and high-absorbance near-infrared optoacoustic contrast agent, E4x12-Cy7. Our near-infrared tracer is based on the amino acid sequence of exendin-4 and targets the glucagon-like peptide-1 receptor (GLP-1R). Cell assays confirmed that E4x12-Cy7 has a high-binding affinity (dissociation constant, Kd, 4.6 ± 0.8 nM). Using the multispectral optoacoustic tomography, we imaged E4x12-Cy7 and optoacoustically visualized β-cell insulinoma xenografts in vivo for the first time. In the future, similar optoacoustic tracers that are specific for β-cells and combines optoacoustic and fluorescence imaging modalities could prove to be important tools for monitoring the pancreas for the progression of diabetes.
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Affiliation(s)
- Sheryl Roberts
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Eshita Khera
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Crystal Choi
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Tejas Navaratna
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Jan Grimm
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
- Program of Molecular Pharmacology, Memorial Sloan Kettering Cancer Center, New York, New York
- Department of Radiology, Weill Cornell Medical College, New York, New York
- Pharmacology Program, Weill Cornell Medical College, New York, New York
| | - Greg M Thurber
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; and
| | - Thomas Reiner
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
- Department of Radiology, Weill Cornell Medical College, New York, New York
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York
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3
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Thurber GM. Reply: From Mice to Humans: The Exocrine Pancreas Does Not Matter in Human GLP-1 Receptor Imaging. J Nucl Med 2021; 62:745-747. [PMID: 33674402 DOI: 10.2967/jnumed.121.262029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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4
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Nessler I, Khera E, Vance S, Kopp A, Qiu Q, Keating TA, Abu-Yousif AO, Sandal T, Legg J, Thompson L, Goodwin N, Thurber GM. Increased Tumor Penetration of Single-Domain Antibody-Drug Conjugates Improves In Vivo Efficacy in Prostate Cancer Models. Cancer Res 2020; 80:1268-1278. [PMID: 31941698 DOI: 10.1158/0008-5472.can-19-2295] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 11/19/2019] [Accepted: 01/07/2020] [Indexed: 01/11/2023]
Abstract
Targeted delivery of chemotherapeutics aims to increase efficacy and lower toxicity by concentrating drugs at the site-of-action, a method embodied by the seven current FDA-approved antibody-drug conjugates (ADC). However, a variety of pharmacokinetic challenges result in relatively narrow therapeutic windows for these agents, hampering the development of new drugs. Here, we use a series of prostate-specific membrane antigen-binding single-domain (Humabody) ADC constructs to demonstrate that tissue penetration of protein-drug conjugates plays a major role in therapeutic efficacy. Counterintuitively, a construct with lower in vitro potency resulted in higher in vivo efficacy than other protein-drug conjugates. Biodistribution data, tumor histology images, spheroid experiments, in vivo single-cell measurements, and computational results demonstrate that a smaller size and slower internalization rate enabled higher tissue penetration and more cell killing. The results also illustrate the benefits of linking an albumin-binding domain to the single-domain ADCs. A construct lacking an albumin-binding domain was rapidly cleared, leading to lower tumor uptake (%ID/g) and decreased in vivo efficacy. In conclusion, these results provide evidence that reaching the maximum number of cells with a lethal payload dose correlates more strongly with in vivo efficacy than total tumor uptake or in vitro potency alone for these protein-drug conjugates. Computational modeling and protein engineering can be used to custom design an optimal framework for controlling internalization, clearance, and tissue penetration to maximize cell killing. SIGNIFICANCE: A mechanistic study of protein-drug conjugates demonstrates that a lower potency compound is more effective in vivo than other agents with equal tumor uptake due to improved tissue penetration and cellular distribution.
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Affiliation(s)
- Ian Nessler
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Eshita Khera
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | | | - Anna Kopp
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | | | | | | | | | - James Legg
- Crescendo Biologics, Cambridge, United Kingdom
| | | | | | - Greg M Thurber
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan. .,Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan
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5
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Khera E, Zhang L, Roberts S, Nessler I, Sandoval D, Reiner T, Thurber GM. Blocking of Glucagonlike Peptide-1 Receptors in the Exocrine Pancreas Improves Specificity for β-Cells in a Mouse Model of Type 1 Diabetes. J Nucl Med 2019; 60:1635-1641. [PMID: 31076502 DOI: 10.2967/jnumed.118.224881] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 05/03/2019] [Indexed: 01/18/2023] Open
Abstract
The diabetes community has long desired an imaging agent to quantify the number of insulin-secreting β-cells, beyond just functional equivalents (insulin secretion), to help diagnose and monitor early stages of both type 1 and type 2 diabetes mellitus. Loss in the number of β-cells can be masked by a compensatory increase in function of the remaining cells. Since β-cells form only about 1% of the pancreas and decrease as the disease progresses, only a few imaging agents, such as exendin, have demonstrated clinical potential to detect a drop in the already scarce signal. However, clinical translation of imaging with exendin has been hampered by pancreatic uptake that is higher than expected in subjects with long-term diabetes who lack β-cells. Exendin binds glucagonlike peptide-1 receptor (GLP-1R), previously thought to be expressed only on β-cells, but recent studies report low levels of GLP-1R on exocrine cells, complicating β-cell mass quantification. Methods: Here, we used a GLP-1R knockout mouse model to demonstrate that exocrine binding of exendin is exclusively via GLP-1R (∼1,000/cell) and not any other receptor. We then used lipophilic Cy-7 exendin to selectively preblock exocrine GLP-1R in healthy and streptozotocin-induced diabetic mice. Results: Sufficient receptors remain on β-cells for subsequent labeling with a fluorescent- or 111In-exendin. Conclusion: Selective GLP-1R blocking, which improves contrast between healthy and diabetic pancreata and provides a potential avenue for achieving the long-standing goal of imaging β-cell mass in the clinic.
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Affiliation(s)
- Eshita Khera
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Liang Zhang
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Sheryl Roberts
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Ian Nessler
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Darleen Sandoval
- Department of Surgery, University of Michigan Medical School, Ann Arbor, Michigan
| | - Thomas Reiner
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York.,Department of Radiology, Weill Cornell Medical College, New York, New York.,Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York; and
| | - Greg M Thurber
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan .,Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan
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6
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Babič A, Vinet L, Chellakudam V, Janikowska K, Allémann E, Lange N. Squalene-PEG-Exendin as High-Affinity Constructs for Pancreatic Beta-Cells. Bioconjug Chem 2018; 29:2531-2540. [PMID: 29869878 DOI: 10.1021/acs.bioconjchem.8b00186] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Novel drug delivery systems targeting native, transplanted, or cancerous beta-cells are of utmost importance. Herein, we present new exendin-4 derivatives with modified unnatural amino acids at strategic positions within the polypeptide sequence. The modified peptides allowed modular orthogonal chemical modifications to attach imaging agents and amphiphilic squalene-PEG groups. The resulting conjugates, SQ-PEG-ExC1-Cy5 and SQ-PEG-ExC40-Cy5 fluorescence probes, display low nanomolar affinity to GLP-1R in fluorescence-based binding assays with EC50 at 1.1 ± 0.2 and 0.8 ± 0.2 nM, respectively. Naturally expressing GLP-1R MIN6 cells and recombinantly transfected CHL-GLP-1R positive cells were specifically targeted by all of the new beta-cell probes in vitro. Specific islet targeting was observed after i.v. injection of SQ-PEG-ExC1-Cy5 with SQ-PEG in normoglycemic mice ex vivo. Semiquantitative biodistribution analysis by epifluorescence indicated prolonged blood half-life (3.8 h) for the amphiphilic Ex conjugate. Liver and pancreas were identified as main biodistribution organs for SQ-PEG-ExC1-Cy5.
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Affiliation(s)
- Andrej Babič
- School of Pharmaceutical Sciences Geneva-Lausanne , University of Geneva, University of Lausanne , 1211 , Geneva , Switzerland
| | - Laurent Vinet
- Institute for Molecular and Translational Imaging , University of Geneva , 1211 , Geneva , Switzerland
| | - Vineetha Chellakudam
- School of Pharmaceutical Sciences Geneva-Lausanne , University of Geneva, University of Lausanne , 1211 , Geneva , Switzerland
| | - Karolina Janikowska
- School of Pharmaceutical Sciences Geneva-Lausanne , University of Geneva, University of Lausanne , 1211 , Geneva , Switzerland
| | - Eric Allémann
- School of Pharmaceutical Sciences Geneva-Lausanne , University of Geneva, University of Lausanne , 1211 , Geneva , Switzerland
| | - Norbert Lange
- School of Pharmaceutical Sciences Geneva-Lausanne , University of Geneva, University of Lausanne , 1211 , Geneva , Switzerland
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7
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Cilliers C, Menezes B, Nessler I, Linderman J, Thurber GM. Improved Tumor Penetration and Single-Cell Targeting of Antibody-Drug Conjugates Increases Anticancer Efficacy and Host Survival. Cancer Res 2017; 78:758-768. [PMID: 29217763 DOI: 10.1158/0008-5472.can-17-1638] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 10/18/2017] [Accepted: 11/28/2017] [Indexed: 12/31/2022]
Abstract
Current antibody-drug conjugates (ADC) have made advances in engineering the antibody, linker, conjugation site, small-molecule payload, and drug-to-antibody ratio (DAR). However, the relationship between heterogeneous intratumoral distribution and efficacy of ADCs is poorly understood. Here, we compared trastuzumab and ado-trastuzumab emtansine (T-DM1) to study the impact of ADC tumor distribution on efficacy. In a mouse xenograft model insensitive to trastuzumab, coadministration of trastuzumab with a fixed dose of T-DM1 at 3:1 and 8:1 ratios dramatically improved ADC tumor penetration and resulted in twice the improvement in median survival compared with T-DM1 alone. In this setting, the effective DAR was lowered, decreasing the amount of payload delivered to each targeted cell but increasing the number of cells that received payload. This result is counterintuitive because trastuzumab acts as an antagonist in vitro and has no single-agent efficacy in vivo, yet improves the effectiveness of T-DM1 in vivo Novel dual-channel fluorescence ratios quantified single-cell ADC uptake and metabolism and confirmed that the in vivo cellular dose of T-DM1 alone exceeded the minimum required for efficacy in this model. In addition, this technique characterized cellular pharmacokinetics with heterogeneous delivery after 1 day, degradation and payload release by 2 days, and in vitro cell killing and in vivo tumor shrinkage 2 to 3 days later. This work demonstrates that the intratumoral distribution of ADC, independent of payload dose or plasma clearance, plays a major role in ADC efficacy.Significance: This study shows how lowering the drug-to-antibody ratio during treatment can improve the intratumoral distribution of a antibody-drug conjugate, with implications for improving the efficacy of this class of cancer drugs. Cancer Res; 78(3); 758-68. ©2017 AACR.
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Affiliation(s)
- Cornelius Cilliers
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Bruna Menezes
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Ian Nessler
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Jennifer Linderman
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Greg M Thurber
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan. .,Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan
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8
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Cilliers C, Nessler I, Christodolu N, Thurber GM. Tracking Antibody Distribution with Near-Infrared Fluorescent Dyes: Impact of Dye Structure and Degree of Labeling on Plasma Clearance. Mol Pharm 2017; 14:1623-1633. [PMID: 28294622 PMCID: PMC5415873 DOI: 10.1021/acs.molpharmaceut.6b01091] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Monoclonal
antibodies labeled with near-infrared (NIR) fluorophores
have potential use in disease detection, intraoperative imaging, and
pharmacokinetic characterization of therapeutic antibodies in both
the preclinical and clinical setting. Recent work has shown conjugation
of NIR fluorophores to antibodies can potentially alter antibody disposition
at a sufficiently high degree of labeling (DoL); however, other reports
show minimal impact after labeling with NIR fluorophores. In this
work, we label two clinically approved antibodies, Herceptin (trastuzumab)
and Avastin (bevacizumab), with NIR dyes IRDye 800CW (800CW) or Alexa
Fluor 680 (AF680), at 1.2 and 0.3 dyes/antibody and examine the impact
of fluorophore conjugation on antibody plasma clearance and tissue
distribution. At 0.3 DoL, AF680 conjugates exhibited similar clearance
to unlabeled antibody over 17 days while 800CW conjugates diverged
after 4 days, suggesting AF680 is a more suitable choice for long-term
pharmacokinetic studies. At the 1.2 DoL, 800CW conjugates cleared
faster than unlabeled antibodies after several hours, in agreement
with other published reports. The tissue biodistribution for bevacizumab–800CW
and −AF680 conjugates agreed well with literature reported
biodistributions using radiolabels. However, the greater tissue autofluorescence
at 680 nm resulted in limited detection above background at low (∼2
mg/kg) doses and 0.3 DoL for AF680, indicating that 800CW is more
appropriate for short-term biodistribution measurements and intraoperative
imaging. Overall, our work shows a DoL of 0.3 or less for non-site-specifically
labeled antibodies (with a Poisson distribution) is ideal for limiting
the impact of NIR fluorophores on antibody pharmacokinetics.
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Affiliation(s)
- Cornelius Cilliers
- Department of Chemical Engineering and ‡Department of Biomedical Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Ian Nessler
- Department of Chemical Engineering and ‡Department of Biomedical Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Nikolas Christodolu
- Department of Chemical Engineering and ‡Department of Biomedical Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Greg M Thurber
- Department of Chemical Engineering and ‡Department of Biomedical Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
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9
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Abbas A, Beamish C, McGirr R, Demarco J, Cockburn N, Krokowski D, Lee TY, Kovacs M, Hatzoglou M, Dhanvantari S. Characterization of 5-(2- 18F-fluoroethoxy)-L-tryptophan for PET imaging of the pancreas. F1000Res 2016; 5:1851. [PMID: 27909574 PMCID: PMC5112576 DOI: 10.12688/f1000research.9129.2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/04/2016] [Indexed: 12/23/2022] Open
Abstract
Purpose: In diabetes, pancreatic beta cell mass declines significantly prior to onset of fasting hyperglycemia. This decline may be due to endoplasmic reticulum (ER) stress, and the system L amino acid transporter LAT1 may be a biomarker of this process. In this study, we used 5-(2-
18F-fluoroethoxy)-L-tryptophan (
18F-L-FEHTP) to target LAT1 as a potential biomarker of beta cell function in diabetes. Procedures: Uptake of
18F-L-FEHTP was determined in wild-type C57BL/6 mice by
ex vivo biodistribution. Both dynamic and static positron emission tomography (PET) images were acquired in wild-type and Akita mice, a model of ER stress-induced diabetes, as well as in mice treated with streptozotocin (STZ). LAT1 expression in both groups of mice was evaluated by immunofluorescence microscopy. Results: Uptake of
18F-L-FEHTP was highest in the pancreas, and static PET images showed highly specific pancreatic signal. Time-activity curves showed significantly reduced
18F-L-FEHTP uptake in Akita mice, and LAT1 expression was also reduced. However, mice treated with STZ, in which beta cell mass was reduced by 62%, showed no differences in
18F-L-FEHTP uptake in the pancreas, and there was no significant correlation of
18F-L-FEHTP uptake with beta cell mass. Conclusions: 18F-L-FEHTP is highly specific for the pancreas with little background uptake in kidney or liver. We were able to detect changes in LAT1 in a mouse model of diabetes, but these changes did not correlate with beta cell function or mass. Therefore,
18F-L-FEHTP PET is not a suitable method for the noninvasive imaging of changes in beta cell function during the progression of diabetes.
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Affiliation(s)
- Ahmed Abbas
- Department of Medical Biophysics, Western University, London, ON, N6A 5C1, Canada
| | - Christine Beamish
- Metabolism and Diabetes Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - Rebecca McGirr
- Metabolism and Diabetes Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada; Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - John Demarco
- Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - Neil Cockburn
- Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - Dawid Krokowski
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Ting-Yim Lee
- Department of Medical Biophysics, Western University, London, ON, N6A 5C1, Canada; Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - Michael Kovacs
- Department of Medical Biophysics, Western University, London, ON, N6A 5C1, Canada; Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - Maria Hatzoglou
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Savita Dhanvantari
- Department of Medical Biophysics, Western University, London, ON, N6A 5C1, Canada; Metabolism and Diabetes Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada; Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada; Department of Pathology and Laboratory Medicine, Western University, London, ON, N6A 5C1, Canada
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10
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Abbas A, Beamish C, McGirr R, Demarco J, Cockburn N, Krokowski D, Lee TY, Kovacs M, Hatzoglou M, Dhanvantari S. Characterization of 5-(2- 18F-fluoroethoxy)-L-tryptophan for PET imaging of the pancreas. F1000Res 2016; 5:1851. [PMID: 27909574 PMCID: PMC5112576 DOI: 10.12688/f1000research.9129.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/04/2016] [Indexed: 10/29/2023] Open
Abstract
Purpose: In diabetes, pancreatic beta cell mass declines significantly prior to onset of fasting hyperglycemia. This decline may be due to endoplasmic reticulum (ER) stress, and the system L amino acid transporter LAT1 may be a biomarker of this process. In this study, we used 5-(2- 18F-fluoroethoxy)-L-tryptophan ( 18F-L-FEHTP) to target LAT1 as a potential biomarker of beta cell function in diabetes. Procedures: Uptake of 18F-L-FEHTP was determined in wild-type C57BL/6 mice by ex vivo biodistribution. Both dynamic and static positron emission tomography (PET) images were acquired in wild-type and Akita mice, a model of ER stress-induced diabetes, as well as in mice treated with streptozotocin (STZ). LAT1 expression in both groups of mice was evaluated by immunofluorescence microscopy. Results: Uptake of 18F-L-FEHTP was highest in the pancreas, and static PET images showed highly specific pancreatic signal. Time-activity curves showed significantly reduced 18F-L-FEHTP uptake in Akita mice, and LAT1 expression was also reduced. However, mice treated with STZ, in which beta cell mass was reduced by 62%, showed no differences in 18F-L-FEHTP uptake in the pancreas, and there was no significant correlation of 18F-L-FEHTP uptake with beta cell mass. Conclusions:18F-L-FEHTP is highly specific for the pancreas with little background uptake in kidney or liver. We were able to detect changes in LAT1 in a mouse model of diabetes, but these changes did not correlate with beta cell function or mass. Therefore, 18F-L-FEHTP PET is not a suitable method for the noninvasive imaging of changes in beta cell function during the progression of diabetes.
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Affiliation(s)
- Ahmed Abbas
- Department of Medical Biophysics, Western University, London, ON, N6A 5C1, Canada
| | - Christine Beamish
- Metabolism and Diabetes Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - Rebecca McGirr
- Metabolism and Diabetes Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
- Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - John Demarco
- Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - Neil Cockburn
- Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - Dawid Krokowski
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Ting-Yim Lee
- Department of Medical Biophysics, Western University, London, ON, N6A 5C1, Canada
- Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - Michael Kovacs
- Department of Medical Biophysics, Western University, London, ON, N6A 5C1, Canada
- Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
| | - Maria Hatzoglou
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Savita Dhanvantari
- Department of Medical Biophysics, Western University, London, ON, N6A 5C1, Canada
- Metabolism and Diabetes Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
- Imaging Program, Lawson Health Research Institute, London, ON, N6A 4V2, Canada
- Department of Pathology and Laboratory Medicine, Western University, London, ON, N6A 5C1, Canada
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11
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Zhang L, Navaratna T, Thurber GM. A Helix-Stabilizing Linker Improves Subcutaneous Bioavailability of a Helical Peptide Independent of Linker Lipophilicity. Bioconjug Chem 2016; 27:1663-72. [PMID: 27327034 DOI: 10.1021/acs.bioconjchem.6b00209] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Stabilized peptides address several limitations to peptide-based imaging agents and therapeutics such as poor stability and low affinity due to conformational flexibility. There is also active research in developing these compounds for intracellular drug targeting, and significant efforts have been invested to determine the effects of helix stabilization on intracellular delivery. However, much less is known about the impact on other pharmacokinetic parameters such as plasma clearance and bioavailability. We investigated the effect of different fluorescent helix-stabilizing linkers with varying lipophilicity on subcutaneous (sc) bioavailability using the glucagon-like peptide-1 (GLP-1) receptor ligand exendin as a model system. The stabilized peptides showed significantly higher protease resistance and increased bioavailability independent of linker hydrophilicity, and all subcutaneously delivered conjugates were able to successfully target the islets of Langerhans with high specificity. The lipophilic peptide variants had slower absorption and plasma clearance than their respective hydrophilic conjugates, and the absolute bioavailability was also lower likely due to the longer residence times in the skin. Their ease and efficiency make double-click helix stabilization chemistries a useful tool for increasing the bioavailability of peptide therapeutics, many of which suffer from rapid in vivo protease degradation. Helix stabilization using linkers of varying lipophilicity can further control sc absorption and clearance rates to customize plasma pharmacokinetics.
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Affiliation(s)
- Liang Zhang
- Department of Chemical Engineering, and ‡Department of Biomedical Engineering University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Tejas Navaratna
- Department of Chemical Engineering, and ‡Department of Biomedical Engineering University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Greg M Thurber
- Department of Chemical Engineering, and ‡Department of Biomedical Engineering University of Michigan , Ann Arbor, Michigan 48109, United States
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Cilliers C, Guo H, Liao J, Christodolu N, Thurber GM. Multiscale Modeling of Antibody-Drug Conjugates: Connecting Tissue and Cellular Distribution to Whole Animal Pharmacokinetics and Potential Implications for Efficacy. AAPS JOURNAL 2016; 18:1117-1130. [PMID: 27287046 DOI: 10.1208/s12248-016-9940-z] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/27/2016] [Indexed: 11/30/2022]
Abstract
Antibody-drug conjugates exhibit complex pharmacokinetics due to their combination of macromolecular and small molecule properties. These issues range from systemic concerns, such as deconjugation of the small molecule drug during the long antibody circulation time or rapid clearance from nonspecific interactions, to local tumor tissue heterogeneity, cell bystander effects, and endosomal escape. Mathematical models can be used to study the impact of these processes on overall distribution in an efficient manner, and several types of models have been used to analyze varying aspects of antibody distribution including physiologically based pharmacokinetic (PBPK) models and tissue-level simulations. However, these processes are quantitative in nature and cannot be handled qualitatively in isolation. For example, free antibody from deconjugation of the small molecule will impact the distribution of conjugated antibodies within the tumor. To incorporate these effects into a unified framework, we have coupled the systemic and organ-level distribution of a PBPK model with the tissue-level detail of a distributed parameter tumor model. We used this mathematical model to analyze new experimental results on the distribution of the clinical antibody-drug conjugate Kadcyla in HER2-positive mouse xenografts. This model is able to capture the impact of the drug-antibody ratio (DAR) on tumor penetration, the net result of drug deconjugation, and the effect of using unconjugated antibody to drive ADC penetration deeper into the tumor tissue. This modeling approach will provide quantitative and mechanistic support to experimental studies trying to parse the impact of multiple mechanisms of action for these complex drugs.
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Affiliation(s)
- Cornelius Cilliers
- Department of Chemical Engineering, University of Michigan, 2800 Plymouth Rd., Ann Arbor, Michigan, 48109, USA
| | - Hans Guo
- Department of Chemical Engineering, University of Michigan, 2800 Plymouth Rd., Ann Arbor, Michigan, 48109, USA
| | - Jianshan Liao
- Department of Chemical Engineering, University of Michigan, 2800 Plymouth Rd., Ann Arbor, Michigan, 48109, USA
| | - Nikolas Christodolu
- Department of Chemical Engineering, University of Michigan, 2800 Plymouth Rd., Ann Arbor, Michigan, 48109, USA
| | - Greg M Thurber
- Department of Chemical Engineering, University of Michigan, 2800 Plymouth Rd., Ann Arbor, Michigan, 48109, USA. .,Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, 48109, USA.
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Mechanistic and quantitative insight into cell surface targeted molecular imaging agent design. Sci Rep 2016; 6:25424. [PMID: 27147293 PMCID: PMC4857130 DOI: 10.1038/srep25424] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 04/15/2016] [Indexed: 12/21/2022] Open
Abstract
Molecular imaging agent design involves simultaneously optimizing multiple probe properties. While several desired characteristics are straightforward, including high affinity and low non-specific background signal, in practice there are quantitative trade-offs between these properties. These include plasma clearance, where fast clearance lowers background signal but can reduce target uptake, and binding, where high affinity compounds sometimes suffer from lower stability or increased non-specific interactions. Further complicating probe development, many of the optimal parameters vary depending on both target tissue and imaging agent properties, making empirical approaches or previous experience difficult to translate. Here, we focus on low molecular weight compounds targeting extracellular receptors, which have some of the highest contrast values for imaging agents. We use a mechanistic approach to provide a quantitative framework for weighing trade-offs between molecules. Our results show that specific target uptake is well-described by quantitative simulations for a variety of targeting agents, whereas non-specific background signal is more difficult to predict. Two in vitro experimental methods for estimating background signal in vivo are compared – non-specific cellular uptake and plasma protein binding. Together, these data provide a quantitative method to guide probe design and focus animal work for more cost-effective and time-efficient development of molecular imaging agents.
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