Publications by authors named "Kimberley S Samkoe"

71 Publications

Examining the Feasibility of Quantifying Receptor Availability Using Cross-Modality Paired-Agent Imaging.

Mol Imaging Biol 2021 Jul 20. Epub 2021 Jul 20.

Thayer School of Engineering, Dartmouth College, 03755, Hanover, NH, USA.

Purpose: The ability to noninvasively quantify receptor availability (RA) in solid tumors is an aspirational goal of molecular imaging, often challenged by the influence of non-specific accumulation of the contrast agent. Paired-agent imaging (PAI) techniques aim to compensate for this effect by imaging the kinetics of a targeted agent and an untargeted isotype, often simultaneously, and comparing the kinetics of the two agents to estimate RA. This is usually accomplished using two spectrally distinct fluorescent agents, limiting the technique to superficial tissues and/or preclinical applications. Applying the approach in humans using conventional imaging modalities is generally infeasible since most modalities are unable to routinely image multiple agents simultaneously. We examine the ability of PAI to be implemented in a cross-modality paradigm, in which the targeted and untargeted agent kinetics are imaged with different modalities and used to recover receptor availability.

Procedures: Eighteen mice bearing orthotopic brain tumors were administered a solution containing three contrast agents: (1) a fluorescent agent targeted to epidermal growth factor receptor (EGFR), (2) an untargeted fluorescent isotype, and (3) a gadolinium-based contrast agent (GBCA) for MRI imaging. The kinetics of all three agents were imaged for 1 h after administration using an MRI-coupled fluorescence tomography system. Paired-agent receptor availability was computed using (1) the conventional all-optical approach using the targeted and untargeted optical agent images and (2) the cross-modality approach using the targeted optical and untargeted MRI-GBCA images. Receptor availability estimates between the two methods were compared.

Results: Receptor availability values using the cross-modality approach were highly correlated to the conventional, single-modality approach (r = 0.94; p < 0.00001).

Conclusion: These results suggest that cross-modality paired-agent imaging for quantifying receptor availability is feasible. Ultimately, cross-modality paired-agent imaging could facilitate rapid, noninvasive receptor availability quantification in humans using hybrid clinical imaging modalities.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11307-021-01629-6DOI Listing
July 2021

TRIPODD: a Novel Fluorescence Imaging Platform for In Situ Quantification of Drug Distribution and Therapeutic Response.

Mol Imaging Biol 2021 Mar 9. Epub 2021 Mar 9.

Biomedical Engineering Department, Oregon Health & Science University, Portland, OR, USA.

Purpose: Personalized medicine has largely failed to produce curative therapies in advanced cancer patients. Evaluation of in situ drug target availability (DTA) concomitant with local protein expression is critical to an accurate assessment of therapeutic efficacy, but tools capable of both are currently lacking.

Procedure: We developed and optimized a fluorescence imaging platform termed TRIPODD (Therapeutic Response Imaging through Proteomic and Optical Drug Distribution), resulting in the only methodology capable of simultaneous quantification of single-cell DTA and protein expression with preserved spatial context within a tumor. Using TRIPODD, we demonstrate the feasibility of combining two complementary fluorescence imaging techniques, intracellular paired agent imaging (iPAI) and cyclic immunofluorescence (cyCIF), conducted with oligonucleotide-conjugated antibodies (Ab-oligos) on tissue samples.

Results: We successfully performed sequential imaging on a single tissue section of iPAI to capture single-cell DTA and local protein expression heterogeneity using Ab-oligo cyCIF. Fluorescence imaging data acquisition was followed by spatial registration resulting in high dimensional data correlating DTA to protein expression at the single-cell level where uptake of a targeted probe alone was not well correlated to protein expression.

Conclusion: Herein, we demonstrated the utility of TRIPODD as a powerful imaging platform capable of interpreting tumor heterogeneity for a mechanistic understanding of therapeutic response and resistance through quantification of drug target availability and proteomic response with preserved spatial context at single-cell resolution.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11307-021-01589-xDOI Listing
March 2021

Intraoperative Detection of Micrometastases in Whole Excised Lymph Nodes Using Fluorescent Paired-Agent Imaging Principles: Identification of a Suitable Staining and Rinsing Protocol.

Mol Imaging Biol 2021 Aug 16;23(4):537-549. Epub 2021 Feb 16.

Biomedical Engineering, Illinois Institute of Technology, Chicago, IL, 60616, USA.

Purpose: Correctly identifying nodal status is recognized as a critical prognostic factor in many cancer types and is essential to guide adjuvant treatment. Currently, surgical removal of lymph nodes followed by pathological examination is commonly performed as a standard-of-care to detect node metastases. However, conventional pathology protocols are time-consuming, yet less than 1 % of lymph node volumes are examined, resulting in a 30-60 % rate of missed micrometastases (0.2-2 mm in size).

Procedures: This study presents a method to fluorescently stain excised lymph nodes using paired-agent molecular imaging principles, which entail co-administration of a molecular-targeted imaging agent with a suitable control (untargeted) agent, whereby any nonspecific retention of the targeted agent is accounted for by the signal from the control agent. Specifically, it was demonstrated that by dual-needle continuous infusion of either an antibody-based imaging agent pair (epidermal growth factor receptor (EGFR) targeted agent: IRDye-800CW labeled Cetuximab; control agent: IRDye-700DX-IgG) or an Affibody-based pair (EGFR targeted Affibody® agent: ABY-029; control agent IRDYe-700DX carboxylate) at 0.3 ml/min.

Results: The results demonstrated the possibility to achieve >99 % sensitivity and > 95 % specificity for detection of a single micrometastasis (~0.2 mm diameter) in a whole lymph node within 22 min of tissue processing time.

Conclusion: The detection capabilities offer substantial improvements over existing intraoperative lymph node biopsy methods (e.g., frozen pathology has a micrometastasis sensitivity <20 %).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11307-021-01587-zDOI Listing
August 2021

Task-based evaluation of fluorescent-guided cancer surgery as a means of identifying optimal imaging agent properties in the context of variability in tumor- and healthy-tissue physiology.

Proc SPIE Int Soc Opt Eng 2020 Feb 19;11222. Epub 2020 Feb 19.

Thayer School of Engineering, Dartmouth College, Hanover, NH.

Fluorescent molecular-guided surgery (FGS) is at a tipping point in terms of clinical approval and adoption in a number cancer applications, with ongoing phase 0 and phase 1 clinical trials being carried out in a wide range of cancers using a wide range of agents. The pharmacokinetics of each of these agents and the physiology of these cancers can differ vastly on a patient-to-patient basis, bringing to question: how can one fairly compare different methodologies (defined as the combination of imaging agent, system, and protocol) and how can existing methodologies be further optimized? To this point, little methodology comparison has been carried out, and the majority of FGS optimization has concerned system development-on the level of maximizing signal-to-noise, dynamic detection range, and sensitivity-independently from traditional agent development-in terms of fluorophore brightness, toxicity, solubility, and binding affinity and specificity. Here we propose an inclusion of tumor and healthy tissue physiology (blood flow, vascular permeability, specific and nonspecific binding sites, extracellular matrix, interstitial pressure, etc…) variability into the optimization process and re-establish well-described task-based metrics for methodology optimization and comparing quality of one methodology to another. Two salient conclusions were identified: (1) contrast-to-background variability is a simple metric that correlates with difficult-to-carry-out task-based metrics for comparing methodologies, and (2) paired-agent imaging protocols offer unique advantages over single-imaging-agent studies for mitigating confounding tumor and background physiology variability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/12.2546700DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7872148PMC
February 2020

Hyperspectral imaging and spectral unmixing for improving whole-body fluorescence cryo-imaging.

Biomed Opt Express 2021 Jan 16;12(1):395-408. Epub 2020 Dec 16.

Thayer School of Engineering at Dartmouth, 14 Engineering Drive, Hanover, NH 03755, USA.

Whole-animal fluorescence cryo-imaging is an established technique that enables visualization of the biodistribution of labeled drugs, contrast agents, functional reporters and cells in detail. However, many tissues produce endogenous autofluorescence, which can confound interpretation of the cryo-imaging volumes. We describe a multi-channel, hyperspectral cryo-imaging system that acquires densely-sampled spectra at each pixel in the 3-dimensional stack. This information enables the use of spectral unmixing to isolate the fluorophore-of-interest from autofluorescence and/or other fluorescent reporters. In phantoms and a glioma xenograft model, we show that the approach improves detection limits, increases tumor contrast, and can dramatically alter image interpretation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/BOE.410810DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7818953PMC
January 2021

Visualization and quantification of pancreatic tumor stroma in fresh tissue via ultraviolet surface excitation.

J Biomed Opt 2021 01;26(1)

Dartmouth College, Thayer School of Engineering, Hanover, New Hampshire, United States.

Significance: The study has confirmed the feasibility of using ultraviolet (UV) excitation to visualize and quantify desmoplasia in fresh tumor tissue of pancreatic adenocarcinoma (PDAC) in an orthotopic xenograft mouse model, which provides a useful imaging platform to evaluate acute therapeutic responses.

Aim: Stromal network of collagen prominent in PDAC tumors is examined by imaging fresh tissue samples stained with histological dyes. Fluorescence signals are color-transferred to mimic Masson's trichrome staining.

Approach: Murine tumor samples were stained with Hoechst, eosin, and rhodamine B and excited at 275-nm. Fluorescence signals in the visible spectrum were captured by a CMOS color camera with high contrast and resolution at whole-tumor slice field of view.

Results: Fluorescence imaging using UV excitation is capable of visualizing collagen deposition in PDAC tumors. Both fluorescence and histology data showed collagen content of up to 30%. The collagen modulation effect due to photodynamic priming treatment was observed showing 13% of collagen reduction. Necrosis area is visible and perfusion imaging using Texas Red dextran is feasible.

Conclusions: The study demonstrates collagen visualization in fresh PDAC tumor samples using UV excitation. This imaging platform also provides quantitative stromal information from fiber analysis and visibility of necrosis and perfusion, suitable for therapeutic response assessment of photodynamic therapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/1.JBO.26.1.016002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7850982PMC
January 2021

Noninvasive quantification of target availability during therapy using paired-agent fluorescence tomography.

Theranostics 2020 14;10(24):11230-11243. Epub 2020 Sep 14.

Thayer School of Engineering, Dartmouth College, Hanover, NH 03755.

Immuno-oncological treatment strategies that target abnormal receptor profiles of tumors are an increasingly important feature of cancer therapy. Yet, assessing receptor availability (RA) and drug-target engagement, important determinants of therapeutic efficacy, is challenging with current imaging strategies, largely due to the complex nonspecific uptake behavior of imaging agents in tumors. Herein, we evaluate whether a quantitative noninvasive imaging approach designed to compensate for nonspecific uptake, MRI-coupled paired-agent fluorescence tomography (MRI-PAFT), is capable of rapidly assessing the availability of epidermal growth factor receptor (EGFR) in response to one dose of anti-EGFR antibody therapy in orthotopic brain tumor models. Mice bearing orthotopic brain tumor xenografts with relatively high EGFR expression (U251) (N=10) or undetectable human EGFR (9L) (N=9) were considered in this study. For each tumor type, mice were either treated with one dose of cetuximab, or remained untreated. All animals were scanned using MRI-PAFT, which commenced immediately after paired-agent administration, and values of RA were recovered using a model-based approach, which uses the entire dynamic sequence of agent uptake, as well as a simplified "snapshot" approach which requires uptake measurements at only two time points. Recovered values of RA were evaluated between groups and techniques. Hematoxylin & eosin (H&E) and immunohistochemical (IHC) staining was performed on tumor specimens from every animal to confirm tumor presence and EGFR status. In animals bearing EGFR(+) tumors, a significant difference in RA values between treated and untreated animals was observed (RA = 0.24 ± 0.15 and 0.61 ± 0.18, respectively, p=0.027), with an area under the curve - receiver operating characteristic (AUC-ROC) value of 0.92. We did not observe a statistically significant difference in RA values between treated and untreated animals bearing EGFR(-) tumors (RA = 0.18 ± 0.19 and 0.27 ± 0.21, respectively; = 0.89; AUC-ROC = 0.55), nor did we observe a difference between treated EGFR(+) tumors compared to treated and untreated EGFR(-) tumors. Notably, the snapshot paired-agent strategy quantified drug-receptor engagement within just 30 minutes of agent administration. Examination of the targeted agent alone showed no capacity to distinguish tumors either by treatment or receptor status, even 24h after agent administration. This study demonstrated that a noninvasive imaging strategy enables rapid quantification of receptor availability in response to therapy, a capability that could be leveraged in preclinical drug development, patient stratification, and treatment monitoring.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7150/thno.45273DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7532673PMC
June 2021

Dual-agent fluorescent labeling of soft-tissue sarcomas improves the contrast based upon targeting both interstitial and cellular components of the tumor milieu.

J Surg Oncol 2020 Dec 3;122(8):1711-1720. Epub 2020 Sep 3.

Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire.

Background: Current practices for fluorescence-guided cancer surgery utilize a single fluorescent agent, but homogeneous distribution throughout the tumor is difficult to achieve. We hypothesize that administering a perfusion and a molecular-targeted agent at their optimal administration-to-imaging time will improve whole-tumor contrast.

Experimental Design: Mice bearing subcutaneous xenograft human synovial sarcomas were administered indocyanine green (ICG) (3 mg/kg) or ABY-029 (48.7 μg/kg)-an epidermal growth factor receptor-targeted Affibody molecule-alone or in combination. Fluorescence contrast and signal distribution were compared between treatment groups. Two commercial fluorescence imaging systems were tested for simultaneous imaging of ICG and ABY-029.

Results: ABY-029 has a moderate positive correlation with viable tumor (ρ = 0.2 ± 0.4), while ICG demonstrated a strong negative correlation (ρ = -0.6 ± 0.1). The contrast-to-variance ratio was highest in the ABY-029 +ICG (2.5 ± 0.8), compared to animals that received ABY-029 (2.3 ± 0.8) or ICG (2.0 ± 0.5) alone. Moreover, the combination of ABY-029 + ICG minimizes the correlation between viable tumor and fluorescence intensity (ρ = -0.1 ± 0.2) indicating the fluorescence signal distribution is more homogeneous throughout the tumor milieu.

Conclusion: Dual-agent imaging utilizing a single channel in a commercial fluorescence-guided imaging system tailored for IRDye 800CW is a promising method to increase tumor contrast in a clinical setting.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jso.26190DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8287542PMC
December 2020

Quantification of Osteosarcoma Mineralization on Plain Radiographs - Novel Software Applications to Assess Response to Chemotherapy.

Proc SPIE Int Soc Opt Eng 2020 Feb 25;11224. Epub 2020 Feb 25.

Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756.

Osteosarcoma is the most common primary malignant bone tumor in children. Patient survival with osteosarcoma is heavily influenced by the response to chemotherapy, measured by tumor necrosis upon histological analysis. Unfortunately, response is not measurable until the time of surgery and therefore modifications to chemotherapy protocol are only made after several weeks of treatment and surgery. Osteosarcoma tumors often demonstrate increased mineralization following the onset of chemotherapy. Furthermore, it has been hypothesized that this mineralization-apparent on radiographs-may correlate with chemotherapy response, however, this has not been demonstrated with qualitative visual evaluation. The ability to non-invasively measure a patient's response to chemotherapy using plain radiographs, which is currently included in the normal clinical workflow, would guide the medical oncologists to tailor treatment for patients with osteosarcoma. After obtaining appropriate multi-center institutional review board approvals, we identified 31patients that possess a pair of pre-and post-chemotherapy radiograph along with the necrosis measure. The images were digitized scans of physical radiographs between 1999 and 2013. Software was designed to measure the signal intensities in the tumor, a region of the soft tissue, air, and healthy bone. The tumor signals were normalized based on the random combination of air, soft tissue or bone, by subtraction or division. The differences in tumor signal between pre-and post-image were plotted against the percent necrosis determined by histological analysis. Different combinations of the normalization methods were compared 2based on the slope, coefficient of determination (R) and Pearson correlation coefficient (ρ).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/12.2546954DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7263182PMC
February 2020

Effect of preoperative cancer treatment on epidermal growth factor receptor (EGFR) receptor expression level in ABY-029 guided sarcoma surgery.

Proc SPIE Int Soc Opt Eng 2020 Feb 19;11222. Epub 2020 Feb 19.

Orthopaedics, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755.

Surgical excision via wide local excision (WLE) of the primary sarcoma tumor is a mainstay of treatment due to the limited effectiveness of chemotherapy and radiation. Even with attempts at WLE, 22-34% of the patient will be diagnosed with a positive margin by the pathologist, necessitating additional radiation or surgery. Recent studies have demonstrated reduced local recurrence when using fluorescence-guided surgery (FGS) to detect residual sarcoma following attempted WLE. ABY-029 is an anti-EGFR Affibody® molecule labeled with IRDye800CW that is currently under Phase 0 human trial for FGS. To date, several studies have been performed to evaluate ABY-029 signal intensity in untreated human sarcoma xenografts; however, many patients undergoing cancer surgery have received pre-operative radiation and/or chemotherapy, which can affect tissue properties and tumor molecule expression level. Determining the effects of radiation and chemotherapy exposure on fluorophore binding in sarcomas may influence best practices in implementing FGS for sarcoma. In this project, fluorophore signal intensities in tumor and surrounding tissue were measured and compared to the receptor concentration determined by immunohistochemistry. Here, we report the result for one EGFR positive synovial sarcoma cell lines, SW982. Four groups of human dose equivalent therapies - control, radiation, chemotherapy (Doxorubicin) and radiation followed by chemotherapy - were given to the tumor-bearing mice. The difference between groups can be used to determine the effects of preoperative sarcoma therapies on EGFR expression, ABY-029 uptake, and optical properties of tissues.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/12.2546963DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7263172PMC
February 2020

Intracellular paired agent imaging enables improved evaluation of tyrosine kinase inhibitor target engagement.

Proc SPIE Int Soc Opt Eng 2020 Feb 19;11219. Epub 2020 Feb 19.

Department of Biomedical Engineering, Oregon Health and Science University, Portland, OR, 97201.

Targeting the aberrant epidermal growth factor receptor (EGFR) signaling pathway is an attractive choice for many cancers (e.g., non-small cell lung carcinoma (NSCLC) and head and neck squamous cell carcinoma (HNSCC)). Despite the development of promising therapeutics, incomplete target engagement and acquired resistance (e.g., mutagenesis and intracellular signaling pathway rewiring) ensure that curative options still elude patients. To address limitations posed by standard drag evaluation assays (e.g., western blot, bulk plasma monitoring, immunohistochemistry), we have developed a novel dynamic, fluorescence-based platform termed intracellular paired agent imaging (iPAI). iPAI quantifies intracellular protein target engagement using two matched small-molecule, cell membrane-permeable agents: one targeted to the protein of interest and one untargeted, which accounts for non-specific therapeutic uptake. Currently, our iPAI panel includes successfully characterized tyrosine kinase inhibitors targeting the kinase binding domain of numerous proteins in the EGFR pathway, including erlotinib (EGFR). Here, we present a pharmacokinetic uptake study using our novel iPAI erlotinib reagents: a targeted erlotinib probed conjugated to silicon tetramethylrhodamine (Erl-SiTMR-T) and an untargeted reagent conjugated to tetramethylrhodaime (Erl-TMR-UT). An initial uptake study in a cell derived xenograft (CDX) model of NSCLC was performed by administering the Erl iPAI reagents systemically via tail vein injection, where drag uptake was quantified in the tumor over time. Excitingly, evidence of heterogeneous uptake was observed in the iPAI injected cohort, displaying distinct drug-uptake within a single tumor. Characterization of additional iPAI agents targeting downstream effectors (e.g., AKT, PI3K, MEK and ERK) is ongoing and will allow us to visualize complex drug-target interactions and quantify their downstream signaling partners during treatment regimens for NSCLC and other cancers. Together, we anticipate these iPAI probes will improve understanding of current limitations in personalized cancer therapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7155938PMC
February 2020

Topical dual-probe staining using quantum dot-labeled antibodies for identifying tumor biomarkers in fresh specimens.

PLoS One 2020 11;15(3):e0230267. Epub 2020 Mar 11.

Thayer School of Engineering at Dartmouth College, Hanover, New Hampshire, United States of America.

Purpose: Rapid, intra-operative identification of tumor tissue in the margins of excised specimens has become an important focus in the pursuit of reducing re-excision rates, especially for breast conserving surgery. Dual-probe difference specimen imaging (DDSI) is an emerging approach that uses the difference in uptake/clearance kinetics between a pair of fluorescently-labeled stains, one targeted to a biomarker-of-interest and the other an untargeted isotype, to reveal receptor-specific images of the specimen. Previous studies using antibodies labeled with either enhanced Raman particles or organic fluorophores have shown promising tumor vs. normal diagnostic performance. Yet, the unique properties of quantum dot-labeled antibody complexes (QDACs), which provide spectrally-distinct fluorescence emission from a common excitation source, make them ideal candidates for this application. Herein, we evaluate the diagnostic performance of QDAC-based DDSI in excised xenografts.

Procedures: Excised fresh specimens of normal tissue and human tumor xenografts with elevated expression of HER2 were stained with a HER2-targeted QDAC and an untargeted QDAC isotype. Stained specimens were imaged on a custom hyperspectral imaging system capable of spectrally separating the quantum dot signatures, and images processed using the DDSI approach. The diagnostic performance of this technique under different incubation temperatures and probe concentrations was evaluated using receiver-operator characteristic analysis.

Results: HER2-targeted QDAC-DDSI was able to distinguish HER2(+) tumors from normal tissue with reasonably high diagnostic performance; however, this performance was sensitive to temperature during the staining procedure. Area under the curve values were 0.61 when staining at room temperature but increased to over 0.81 when staining at 37 °C. Diagnostic performance was not affected by increasing stain concentration.

Conclusions: This study is the first to report dual-probe difference imaging of specimens using QDACs and hyperspectral imaging. Our results show promising diagnostic performance under certain conditions, and compel further optimization and evaluation of this intra-operative margin assessment technique.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0230267PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7065915PMC
June 2020

A paired-agent fluorescent molecular imaging strategy for quantifying antibody drug target engagement in window chamber xenograft models.

Proc SPIE Int Soc Opt Eng 2020 Feb 19;11219. Epub 2020 Feb 19.

Biomedical Engineering, Illinois Institute of Technology, Chicago, IL.

A paired-agent fluorescent molecular imaging strategy is presented as a method to measure drug target engagement in whole tumor imaging. The protocol involves dynamic imaging of a pair of targeted and control imaging agents prior to and following antibody therapy. Simulations demonstrated that antibody "drug target engagement" can be estimated within a 15%-error over a wide range of tumor physiology (blood flow, vascular permeability, target density) and antibody characteristics (affinity, binding rates). Experimental results demonstrated the first in vivo detection of binding site barrier, highlighting the potential for this methodology to provide novel insights in drug distribution/binding imaging.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/12.2545182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8236091PMC
February 2020

Effect of nonspecific binding of imaging agents to plasma protein in the paired-agent imaging for resection during surgery (PAIRS).

Proc SPIE Int Soc Opt Eng 2020 Feb 19;11219. Epub 2020 Feb 19.

Geisel School of Medicine, Dartmouth College, Hanover, NH 03755.

Long-term survival of head and neck squamous cell carcinoma (HNSCC) patients have proven to be correlated with negative surgical margins. Paired-Agent Imaging for Resection during Surgery (PAIRS) is capable of drawing the fine line between tumor and normal tissue by employing a control imaging-agent, which is co-administered with the targeted imaging agent to account for nonspecific signal. PAI is highly dependent on the parallel paired-agent delivery and static quantum yield of the agent to trace the molecular concentration. However, it is well known that nonspecific binding of fluorescence probes to plasma proteins can change its delivery, dissociation constant, and quantum yield. A thorough evaluation of the effect of plasma protein binding in the estimation of receptor concentration was performed for the paired-agents in this study. We are planning to evaluate ABY-029, an anti-epithelial growth factor receptor (EGFR) Affibody, and IRDye 700DX as a control agent. The plasma-dependent change in fluorescence intensity, percent binding, and distribution kinetics will be studied for each agent alone, and in combination. In this proceeding, the absorption, emission patterns for the targeted agent, ABY-029, measured by UV-Vis, fluorometer, and Pearl were shown. Initial studies indicate that binding to Bovine serum albumin (BSA), human serum albumin (HSA) and EGFR can introduce the Solvatochromic shift, which will change the absorption and emission pattern for ABY-029. Computational modeling will be performed to determine how each of these changes will affect the determined BP, and thus detection of tumors from normal tissue.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8192242PMC
February 2020

Noninvasive imaging of dual-agent uptake in glioma and normal tissue using MRI-coupled fluorescence tomography.

Proc SPIE Int Soc Opt Eng 2019 Feb 1;10874. Epub 2019 Mar 1.

Thayer School of Engineering, Dartmouth College, Hanover, NH 03755.

As the role of immuno-oncological therapeutics expands, the capacity to noninvasively quantify molecular targets and drug-target engagement is increasingly critical to drug development efforts and treatment monitoring. Previously, we showed that MRI-coupled dual-agent fluorescence tomography (FMT) is capable of estimating the concentration of epidermal growth factor receptor (EGFR) in orthotopic glioma models noninvasively. This approach uses the dynamic information of two fluorescent agents (a targeted agent and untargeted isotype) to estimate tumor receptor concentration in vivo. This approach generally relies on the two tracers having similar kinetics in normal tissues, which may not always be the case. Herein, we describe an additional channel added to the MRI-FMT system which measures the uptake of both agents in the normal muscle, data which can be used to compensate for differing kinetic behavior.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/12.2510515DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6953723PMC
February 2019

Effect of staining temperature on topical dual stain imaging of tissue specimens for tumor identification.

Proc SPIE Int Soc Opt Eng 2019 Feb 7;10862. Epub 2019 Mar 7.

Thayer School of Engineering, Dartmouth College, 14 Engineering Dr., Hanover, NH USA 03755-8001.

In the pursuit of reducing re-excision rates in breast conserving surgery, a dual probe specimen staining technique has emerged as a promising approach to identify positive margins during surgery. This approach generally involves staining the tissue with a fluorescent dye targeted to a biomarker of interest, such as a cell surface receptor, and an untargeted counterpart, imaging both dyes and using the two images together to compensate for instrumentation inhomogeneities and non-specific uptake. A growing body of literature suggests that this approach can effectively discriminate tumor and normal tissue in gross fresh specimens in reasonable timeframes. However, the robustness of the staining protocol is still under investigation as all parameters have not been fully evaluated. In this paper, we examine the effect of staining temperature on diagnostic performance. Tumor (overexpressing EGFR) and normal fresh specimens were stained at room temperature or 37 °C and diagnostic performance compared using area under the curve (AUC) from receiver operator characteristic (ROC) analysis. The results suggest that the use of Licor IRDye800CW-labeled anti-EGFR antibody and Licor IRdye680RD-labeled control antibody as the probe pair is not significantly affected by staining temperature, in contrast to our experience with quantum-dot labeled antibodies. The robustness of the technique using these stains is reassuring and simplifies the staining protocol.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/12.2509848DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6953721PMC
February 2019

On the use of fluorescein-based contrast agents as analogs to MRI-gadolinium agents for imaging brain tumors.

Proc SPIE Int Soc Opt Eng 2019 Feb 7;10862. Epub 2019 Mar 7.

Department of Surgery, Geisel School of Medicine, 1 Rope Ferry Rd., Hanover, NH USA 03755.

Magnetic resonance imaging (MRI) of gadolinium (Gd)-based contrast agents plays a central role in managing the treatment of intracranial tumors. These images are involved in diagnosis, surgical planning, surgical navigation, and postoperative assessment of extent of resection. Replicating the information from Gd-MRI in the visual surgical field using fluorescent agents that behave similar to gadolinium in vivo would represent a major advance for surgical intervention of these tumors, and could provide robust compensation information to update pre-operative MRI images during surgery. In this paper, we examine the uptake of a Gd-based contrast agent in orthotopic tumor models and compare this behavior to two fluorescein-based contrast agents; specifically, clinical-grade sodium fluorescein (NaFl) and a 900 Da pegylated form of fluorescein. We show that the pegylated form of fluorescein is a more promising Gd-analog candidate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/12.2510905DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6953720PMC
February 2019

High-Resolution Ex Vivo Elastography to Characterize Tumor Stromal Heterogeneity In Situ in Pancreatic Adenocarcinoma.

IEEE Trans Biomed Eng 2020 09 1;67(9):2490-2496. Epub 2020 Jan 1.

Objective: Tumor stiffening in pancreatic adenocarcinoma (PDAC) has been linked to cancer progression and lack of therapy response, yet current elastography tools cannot map stiffness in a whole tumor field-of-view with biologically relevant spatial resolution. Therefore, this study was developed to assess stiffness heterogeneity and geometrical patterns across whole PDAC xenograft ex vivo tumors.

Methods: The ex vivo elastography (EVE) mapping system was capable of creating stiffness map at 300-micron spatial resolution under a 5-20 mm field of view relevant to whole tumor assessment. The stiffness value at each location was determined by compression testing and an absolute tumor Young's modulus map was calculated based on the calibration between the system and ultrasound elastography (R = 0.95).

Results: Two PDAC tumor lines AsPC-1 and BxPC-3 implanted in xenograft models were assessed to show tumor stiffness and its linear relationship to collagen content (R = 0.59). EVE was able to capture stiffness heterogeneity ranging between 5 and 100 kPa in pancreatic tumors with collagen content up to 25%. More importantly, data shows the inverse relationship of local stiffness to local drug distribution (R = 0.66) and vessel patency (R = 0.61) in both PDAC tumor lines.

Conclusion: The results suggested that elastography could be utilized to predict drug penetration in PDAC tumors or assess response to biological modifying adjunct therapies.

Significance: This study presents the first attempt to map out stiffness on a biologically relevant spatial scale across whole PDAC tumor slices with spatial resolution in the hundreds of microns.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1109/TBME.2019.2963562DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7494001PMC
September 2020

Paired-agent imaging for detection of head and neck cancers.

Proc SPIE Int Soc Opt Eng 2019 Feb 26;10853. Epub 2019 Feb 26.

Department of Biomedical Engineering, llinois Institute of Technology, Chicago, Illinois, 60616.

Head and neck cancers overwhelmingly overexpress epidermal growth factor receptor (EGFR). This overexpression has been utilized for head and neck cancers using molecular targeted agents for therapy and cancer cell detection. Significant progress has been made in using EGFR-targeted fluorescent antibody and Affibody molecule agents for fluorescent guided surgery in head and neck cancers. Although success in achieving tumor-to-background ratio of 3-5 have been achieved, the field is limited by the non-specific fluorescence in normal tissues as well as EGFR specific fluorescence in the oral cavity. We propose that paired-agent imaging (PAI) could improve the contrast between tumor and normal tissue by removing the fluorescent signal arising from non-specific binding. Here, ABY-029 - an anti-EGFR Affibody molecule labeled with IRDye 800CW - and IRDye 680RD conjugated to Affibody Control Imaging Agent molecule (IR680-Aff) are used as targeted and untargeted control agents, respectively, in a panel of head and neck squamous cell carcinomas (HNSCC) to test the ability of PAI to increase tumor detection. Initial results demonstrate that binding potential, a value proportional to receptor concentration, correlates well to EGFR expression but experimental limitations prevented pixel-by-pixel analysis that was desired. Although promising, a more rigorous and well-defined experimental protocol is required to align EGFR immunohistochemistry with binding potential and fluorescence intensity. Additionally, a new set of paired-agents, ABY-029 and IRDye 700DX, are successfully tested in naïve mice and will be carried forward for clinical translation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/12.2510897DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6827556PMC
February 2019

Measuring microdose ABY-029 fluorescence signal in a primary human soft-tissue sarcoma resection.

Proc SPIE Int Soc Opt Eng 2019 Feb 22;10862. Epub 2019 May 22.

Thayer School of Engineering, Dartmouth College, Hanover, NH, 03755.

Microdose administration of ABY-029, an anti-epidermal growth factor receptor Affibody molecule conjugated to IRDye 800CW, is being studied in a Phase 0 trial for resection of soft-tissue sarcomas. The excised tissue of a single patient in the microdose administration group was imaged with both a wide-field fluorescence surgical system and a flat-bed scanning fluorescence imaging system. Here the resultant fluorescence from a breadloaf section of the primary tumor specimen and six region-specific tissue samples collected from that breadloaf are compared using these two imaging systems - a flatbed, black-box, fluorescence scanning system, the Odyssey CLx, and a open-air, wide-field, pre-clinical surgical imaging system, the Solaris. Florescence signal is compared using a variety of methods including: mean, standard deviation, variance, tumor-to-background ratio, biological-variance ratio, and contrast-to-noise ratio. The images produced from the Odyssey scanner have higher signal variance but more accurately represent the EGFR expression in small tissue sections. The Solaris system has higher depth sensitivity and volume averaging, and as such has lower signal variation and higher contrast-to-noise ratio.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/12.2510935DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6783124PMC
February 2019

Preclinical imaging of epidermal growth factor receptor with ABY-029 in soft-tissue sarcoma for fluorescence-guided surgery and tumor detection.

J Surg Oncol 2019 Jun 4;119(8):1077-1086. Epub 2019 Apr 4.

Department of Orthaepedics, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire.

Background And Objectives: Fluorescence-guided surgery using epidermal growth factor receptor (EGFR) targeting has been performed successfully in clinical trials using a variety of fluorescent agents. We investigate ABY-029 (anti-EGFR Affibody molecule labeled with IRDye 800CW) compared with a small-molecule perfusion agent, IRDye 700DX carboxylate, in a panel of soft-tissue sarcomas with varying levels of EGFR expression and vascularization.

Methods: Five xenograft soft-tissue sarcoma cell lines were implanted into immunosuppressed mice. ABY-029 and IRDye 700DX were each administered at 4.98 μM. Fluorescence from in vivo and ex vivo (fresh and formalin-fixed) fixed tissues were compared. The performance of three fluorescence imaging systems was assessed for ex vivo tissues.

Results: ABY-029 is retained longer within tumor tissue and achieves higher tumor-to-background ratios both in vivo and ex vivo than IRDye 700DX. ABY-029 fluorescence is less susceptible to formalin fixation than IRDye 700DX, but both agents have disproportional signal loss in a variety of tissues. The Pearl Impulse provides the highest contrast-to-noise ratio, but all systems have individual advantages.

Conclusions: ABY-029 demonstrates promise to assist in wide local excision of soft-tissue sarcomas. Further clinical evaluation of in situ or freshly excised ex vivo tissues using fluorescence imaging systems is warranted.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jso.25468DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6529257PMC
June 2019

Simultaneous extracellular and intracellular quantification of EGFR using paired-agent imaging in an tumor model.

Proc SPIE Int Soc Opt Eng 2019 Feb 28;10859. Epub 2019 Feb 28.

Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, Illinois, 60616.

Quantification of protein concentrations is often a static and tissue destructive technique. Paired-agent imaging (PAI) using matched targeted and untargeted agents has been established as a dynamic method for quantifying the extracellular domain of epidermal growth factor receptor (EGFR) in a variety of tumor lines. Here we extend the PAI model to simultaneously quantify the extracellular and intracellular regions of EGFR using novel cell membrane permeable fluorescent small molecules, TRITC-erlotinib (targeted) and BODIPY-N-erlotinib (non-binding control isoform) synthesized in house. An EGFR overexpressing squamous cell carcinoma cell xenograft tumor, A431, was implanted on the chorioallantoic membrane (CAM) of the embryonated chicken egg. In total six fluorescent molecules were administered and monitored over 1 h using multi-spectral imaging. EGFR concentrations were determined using both extracellular and intracellular PAI methods. The fluorescent molecules used for extracellular PAI were ABY-029, an anti-EGFR Affibody molecule conjugated to IRDye 800CW, and a Control Imaging Agent Affibody molecule conjugated to IRDye 680RD. The intracellular PAI (iPAI) fluorescent molecules were cell membrane penetrating TRITC-erlotinib, BODIPY-N-erlotinb, and BODIPY TR carboxylate, as well as cell membrane impermeant control agent, Alexa Fluor 647 carboxylate. Results from simultaneous imaging of both the extracellular and intracellular binding domains of EGFR indicate that concentrations of intracellular EGFR are higher than extracellular. This is anticipated as EGFR exists in two distinct populations in cells, cell membrane bound and internalized, activated protein. iPAI is a promising new method for quantifying intracellular proteins in a rapid tumor model on the chicken CAM.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/12.2510778DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7158268PMC
February 2019

Elucidating the kinetics of sodium fluorescein for fluorescence-guided surgery of glioma.

J Neurosurg 2018 09;131(3):724-734

1Thayer School of Engineering and.

Objective: The use of the optical contrast agent sodium fluorescein (NaFl) to guide resection of gliomas has been under investigation for decades. Although this imaging strategy assumes the agent remains confined to the vasculature except in regions of blood-brain barrier (BBB) disruption, clinical studies have reported significant NaFl signal in normal brain tissue, limiting tumor-to-normal contrast. A possible explanation arises from earlier studies, which reported that NaFl exists in both pure and protein-bound forms in the blood, the former being small enough to cross the BBB. This study aims to elucidate the kinetic binding behavior of NaFl in circulating blood and its effect on NaFl accumulation in brain tissue and tumor contrast. Additionally, the authors examined the blood and tissue kinetics, as well as tumor uptake, of a pegylated form of fluorescein selected as a potential optical analog of gadolinium-based MRI contrast agents.

Methods: Cohorts of mice were administered one of the following doses/forms of NaFl: 1) high human equivalent dose (HED) of NaFl, 2) low HED of NaFl, or 3) pegylated form of fluorescein. In each cohort, groups of animals were euthanized 15, 30, 60, and 120 minutes after administration for ex vivo analysis of fluorescein fluorescence. Using gel electrophoresis and fluorescence imaging of blood and brain specimens, the authors quantified the temporal kinetics of bound NaFl, unbound NaFl, and pegylated fluorescein in the blood and normal brain tissue. Finally, they compared tumor-to-normal contrast for NaFl and pegylated-fluorescein in U251 glioma xenografts.

Results: Administration of NaFl resulted in the presence of unbound and protein-bound NaFl in the circulation, with unbound NaFl constituting up to 70% of the signal. While protein-bound NaFl was undetectable in brain tissue, unbound NaFl was observed throughout the brain. The observed behavior was time and dose dependent. The pegylated form of fluorescein showed minimal uptake in brain tissue and improved tumor-to-normal contrast by 38%.

Conclusions: Unbound NaFl in the blood crosses the BBB, limiting the achievable tumor-to-normal contrast and undermining the inherent advantage of tumor imaging in the brain. Dosing and incubation time should be considered carefully for NaFl-based fluorescence-guided surgery (FGS) of glioma. A pegylated form of fluorescein showed more favorable normal tissue kinetics that translated to higher tumor-to-normal contrast. These results warrant further development of pegylated-fluorescein for FGS of glioma.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3171/2018.4.JNS172644DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6995036PMC
September 2018

Optimizing Glioma Detection Using an EGFR-Targeted Fluorescent Affibody.

Photochem Photobiol 2018 11 28;94(6):1167-1171. Epub 2018 Sep 28.

Thayer School of Engineering, Dartmouth College, Hanover, NH.

Since many types of cancers overexpress EGFR, this surface receptor has been used as a target for therapy or diagnosis of malignant disease. Uptake kinetics of EGFR-targeted fluorescent Affibody (ABY-029) were studied with a view toward optimizing efficacy of tumor detection in a glioma as a function of both delivered dose and concurrent administration of unlabeled cetuximab (an EGFR antagonist). U251 glioma cells were inoculated in brain of nude rats, and the fluorescence from each brain was analyzed after the administration of ABY-029. Although cetuximab was able to systematically block ABY-029 binding to EGFR in a dose-dependent manner in cell culture, no influence on the tumor-to-normal brain contrast was seen when unlabeled cetuximab was administered prior to ABY-029. Ex vivo imaging of ABY-029 fluorescence showed increasing values of the tumor-to-normal brain ratio with an increasing injected dose. A saturation value was obtained at a dose of 245 μg kg which represents a 10-fold increase over a "microdose" value. According to FDA, the microdose of protein products is considered ≤30 nanomoles due to its difference in molecular weight as compared to synthetic drugs. This observation indicates that glioma detection will be optimal if the ABY-029 dose exceeds the "microdose" value.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/php.13003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6234080PMC
November 2018

Application of Fluorescence-Guided Surgery to Subsurface Cancers Requiring Wide Local Excision: Literature Review and Novel Developments Toward Indirect Visualization.

Cancer Control 2018 Jan-Mar;25(1):1073274817752332

5 Department of Orthopaedics, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.

The excision of tumors by wide local excision is challenging because the mass must be removed entirely without ever viewing it directly. Positive margin rates in sarcoma resection remain in the range of 20% to 35% and are associated with increased recurrence and decreased survival. Fluorescence-guided surgery (FGS) may improve surgical accuracy and has been utilized in other surgical specialties. ABY-029, an anti-epidermal growth factor receptor Affibody molecule covalently bound to the near-infrared fluorophore IRDye 800CW, is an excellent candidate for future FGS applications in sarcoma resection; however, conventional methods with direct surface tumor visualization are not immediately applicable. A novel technique involving imaging through a margin of normal tissue is needed. We review the past and present applications of FGS and present a novel concept of indirect FGS for visualizing tumor through a margin of normal tissue and aiding in excising the entire lesion as a single, complete mass with tumor-free margins.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/1073274817752332DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5933571PMC
August 2018

Development and evaluation of a connective tissue phantom model for subsurface visualization of cancers requiring wide local excision.

J Biomed Opt 2017 12;22(12):1-12

Dartmouth-Hitchcock Medical Center, Department of Orthopaedics, Lebanon, New Hampshire, United States.

Wide local excision (WLE) of tumors with negative margins remains a challenge because surgeons cannot directly visualize the mass. Fluorescence-guided surgery (FGS) may improve surgical accuracy; however, conventional methods with direct surface tumor visualization are not immediately applicable, and properties of tissues surrounding the cancer must be considered. We developed a phantom model for sarcoma resection with the near-infrared fluorophore IRDye 800CW and used it to iteratively define the properties of connective tissues that typically surround sarcoma tumors. We then tested the ability of a blinded surgeon to resect fluorescent tumor-simulating inclusions with ∼1-cm margins using predetermined target fluorescence intensities and a Solaris open-air fluorescence imaging system. In connective tissue-simulating phantoms, fluorescence intensity decreased with increasing blood concentration and increased with increasing intralipid concentrations. Fluorescent inclusions could be resolved at ≥1-cm depth in all inclusion concentrations and sizes tested. When inclusion depth was held constant, fluorescence intensity decreased with decreasing volume. Using targeted fluorescence intensities, a blinded surgeon was able to successfully excise inclusions with ∼1-cm margins from fat- and muscle-simulating phantoms with inclusion-to-background contrast ratios as low as 2∶1. Indirect, subsurface FGS is a promising tool for surgical resection of cancers requiring WLE.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/1.JBO.22.12.121613DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5741805PMC
December 2017

Assessing daylight & low-dose rate photodynamic therapy efficacy, using biomarkers of photophysical, biochemical and biological damage metrics in situ.

Photodiagnosis Photodyn Ther 2017 Dec 14;20:227-233. Epub 2017 Oct 14.

Thayer School of Engineering, Dartmouth College, Hanover, NH, 03755, USA; Department of Surgery, Geisel School of Medicine, Dartmouth College, Lebanon, NH, 03756, USA. Electronic address:

Background: Sunlight can activate photodynamic therapy (PDT), and this is a proven strategy to reduce pain caused byconventional PDT treatment, but assessment of this and other alternative low dose rate light sources, and their efficacy, has not been studied in an objective, controlled pre-clinical setting. This study used three objective assays to assess the efficacy of different PDT treatment regimens, using PpIX fluorescence as a photophysical measure, STAT3 cross-linking as a photochemical measure, and keratinocyte damage as a photobiological measure.

Methods: Nude mouse skin was used along with in vivo measures of photosensitizer fluorescence, keratinocyte nucleus damage from pathology, and STAT3 cross-linking from Western blot analysis. Light sources compared included a low fluence rate red LED panel, compact fluorescent bulbs, halogen bulbs and direct sunlight, as compared to traditional PDT delivery with conventional and fractionated high fluence rate red LED light delivery.

Results: Of the three biomarkers, two had strong correlation to the PpIX-weighted light dose, which is calculated as the product of the treatment light dose (J/cm) and the normalized PpIX absorption spectra. Comparison of STAT3 cross-linking to PpIX-weighted light dose had an R=0.74, and comparison of keratinocyte nuclear damage R=0.70. There was little correlation to PpIX fluorescence. These assays indicate most of the low fluence rate treatment modalities were as effective as conventional PDT, while fractionated PDT showed the most damage.

Conclusions: Daylight or artificial light PDT provides an alternative schedule for delivery of drug-light treatment, and this pre-clinical assay demonstrated that in vivo assays of damage could be used to objectively predict a clinical outcome in this altered delivery process.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.pdpdt.2017.10.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5718943PMC
December 2017

Toxicity and Pharmacokinetic Profile for Single-Dose Injection of ABY-029: a Fluorescent Anti-EGFR Synthetic Affibody Molecule for Human Use.

Mol Imaging Biol 2017 08;19(4):512-521

Department of Surgery, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, NH, 03755, USA.

Purpose: ABY-029, a synthetic Affibody peptide, Z03115-Cys, labeled with a near-infrared fluorophore, IRDye® 800CW, targeting epidermal growth factor receptor (EGFR) has been produced under good manufacturing practices for a US Food and Drug Administration-approved first-in-use human study during surgical resection of glioma, as well as other tumors. Here, the pharmacology, phototoxicity, receptor activity, and biodistribution studies of ABY-029 were completed in rats, prior to the intended human use.

Procedures: Male and female Sprague Dawley rats were administered a single intravenous dose of varying concentrations (0, 245, 2449, and 24,490 μg/kg corresponding to 10×, 100×, and 1000× an equivalent human microdose level) of ABY-029 and observed for up to 14 days. Histopathological assessment of organs and tissues, clinical chemistry, and hematology were performed. In addition, pharmacokinetic clearance and biodistribution of ABY-029 were studied in subgroups of the animals. Phototoxicity and ABY-029 binding to human and rat EGFR were assessed in cell culture and on immobilized receptors, respectively.

Results: Histopathological assessment and hematological and clinical chemistry analysis demonstrated that single-dose ABY-029 produced no pathological evidence of toxicity at any dose level. No phototoxicity was observed in EGFR-positive and EGFR-negative glioma cell lines. Binding strength and pharmacokinetics of the anti-EGFR Affibody molecules were retained after labeling with the dye.

Conclusion: Based on the successful safety profile of ABY-029, the 1000× human microdose 24.5 mg/kg was identified as the no observed adverse effect level following intravenous administration. Conserved binding strength and no observed light toxicity also demonstrated ABY-029 safety for human use.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11307-016-1033-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648591PMC
August 2017

Simultaneous Fluorescent Markers for Perfusion, Protoporphyrin Metabolism, and EGFR Expression for Optically Guided Identification of Orthotopic Glioma.

Clin Cancer Res 2017 May 31;23(9):2203-2212. Epub 2016 Oct 31.

Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire.

While extent of tumor resection is an important predictor of outcome in glioma, margin delineation remains challenging due to lack of inherent contrast between tumor and normal parenchyma. Fluorescence-guided surgery is promising for its ability to enhance contrast through exogenous fluorophores; however, the specificity and sensitivity of the underlying contrast mechanism and tumor delivery and uptake vary widely across approved and emerging agents. Rats with orthotopic F98 wild-type and F98 EGFR-positive (EGFR) gliomas received administration of IRDye680RD, 5-aminioleuvulinic acid, and ABY-029-markers of perfusion, protoporphyrin metabolism, and EGFR expression, respectively. imaging demonstrates the contrast mechanism-dependent spatial heterogeneity and enables within-animal comparisons of tumor-to-background ratio (TBR). Generally, ABY-029 outperformed PpIX in F98 orthotopic tumor margins and core (50% and 60% higher TBR, respectively). PpIX outperformed ABY-029 in F98 margins by 60% but provided equivalent contrast in the bulk tumor. IRDye680RD provided little contrast, having an average TBR of 1.7 ± 0.2. The unique spatial patterns of each agent were combined into a single metric, the multimechanistic fluorescence-contrast index (MFCI). ABY-029 performed best in EGFR tumors (91% accuracy), while PpIX performed best in wild-type tumors (87% accuracy). Across all groups, ABY-029 and PpIX performed similarly (80% and 84%, respectively) but MFCI was 91% accurate, supporting multiagent imaging when tumor genotype was unknown. Human use of ABY-029 for glioma resection should enhance excision of EGFR tumors and could be incorporated into current PpIX strategies to further enhance treatment in the general glioma case. .
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1158/1078-0432.CCR-16-1400DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5411329PMC
May 2017

Optical tracer size differences allow quantitation of active pumping rate versus Stokes-Einstein diffusion in lymphatic transport.

J Biomed Opt 2016 10;21(10):100501

Dartmouth College, Thayer School of Engineering, 14 Engineering Drive, Hanover, New Hampshire 03755, United StatesbGeisel School of Medicine, Department of Surgery, 1 Rope Ferry Road, Hanover, New Hampshire 03755, United States.

Lymphatic uptake of interstitially administered agents occurs by passive convective–diffusive inflow driven by interstitial concentration and pressure, while the downstream lymphatic transport is facilitated by active propulsive contractions of lymphatic vessel walls. Near-infrared fluorescence imaging in mice was used to measure these central components of lymphatic transport for the first time, using two different-sized molecules––methylene blue (MB) and fluorescence-labeled antibody immunoglobulin G (IgG)-IRDye 680RD. This work confirms the hypothesis that lymphatic passive inflow and active propulsion rates can be separated based upon the relative differences in Stokes–Einstein diffusion coefficient. This coefficient specifically affects the passive-diffusive uptake when the interstitial volume and pressure are constant. Parameters such as mean time-to-peak signal, overall fluorescence signal intensities, and number of active peristaltic pulses, were estimated from temporal imaging data. While the mean time to attain peak signal representative of diffusion-dominated flow in the lymph vessels was 0.6±0.2??min for MB and 8±6??min for IgG, showing a size dependence, the active propulsion rates were 3.4±0.8??pulses/min and 3.3±0.5??pulses/min, respectively, appearing size independent. The propulsion rates for both dyes decreased with clearance from the interstitial injection-site, indicating intrinsic control of the smooth muscles in response to interstitial pressure. This approach to size-comparative agent flow imaging of lymphatic function can enable noninvasive characterization of diseases related to uptake and flow in lymph networks.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1117/1.JBO.21.10.100501DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5067306PMC
October 2016
-->