Correction: Garza-Morales et al. Temozolomide Enhances Triple-Negative Breast Cancer Virotherapy In Vitro. Cancers 2018, 10, 144

Error in Figure [...].

Influence of structural moieties in squaraine dyes on optoacoustic signal shape and intensity

Optoacoustic imaging has grown in clinical relevance due to inherent advantages in sensitivity, resolution, and imaging depth, but the development of contrast agents is lacking. This study assesses the influence of structural features of squaraine dyes on optoacoustic activity through computational models, in vitro testing, and in vivo experimentation. The squaraine scaffold was decorated with halogens and side-chain extensions. Extension of side chains and heavy halogenation of squaraines both increased optoacoustic signals individually, although they had a more significant effect in tandem. Density functional theory models suggest that the origin of the increased optoacoustic signal is the increase in transition dipole moment and vibrational entropy, which manifested as increased absorbance in near-infrared region (NIR) wavelengths and decreased fluorescence quantum yield. This study provides insight into the structure-function relationships that will lead guiding principles for optimizing optoacoustic contrast agents. Further developments of squaraines and other agents will further increase the relevance of optoacoustic imaging in a clinical setting.

Erratum: Influence of structural moieties in squaraine dyes on optoacoustic signal shape and intensity

[This corrects the article PMC11087056.].

Dynamic 2-deoxy-D-glucose-enhanced multispectral optoacoustic tomography for assessing metabolism and vascular hemodynamics of breast cancer

Clinical tools for measuring tumor vascular hemodynamics, such as dynamic contrast-enhanced MRI, are clinically important to assess tumor properties. Here we explored the use of multispectral optoacoustic tomography (MSOT), which has a high spatial and temporal resolution, to measure the intratumoral pharmacokinetics of a near-infrared-dye-labeled 2-Deoxyglucose, 2-DG-800, in orthotropic 2-LMP breast tumors in mice. As uptake of 2-DG-800 is dependent on both vascular properties, and glucose transporter activity - a widely-used surrogate for metabolism, we evaluate hemodynamics of 2-DG-MP by fitting the dynamic MSOT signal of 2-DG-800 into two-compartment models including the extended Tofts model (ETM) and reference region model (RRM). We showed that dynamic 2-DG-enhanced MSOT (DGE-MSOT) is powerful in acquiring hemodynamic rate constants, including Ktrans and Kep, via systemically injecting a low dose of 2-DG-800 (0.5 µmol/kg b.w.). In our study, both ETM and RRM are efficient in deriving hemodynamic parameters in the tumor. Area-under-curve (AUC) values (which correlate to metabolism), and Ktrans and Kep values, can effectively distinguish tumor from muscle. Hemodynamic parameters also demonstrated correlations to hemoglobin, oxyhemoglobin, and blood oxygen level (SO2) measurements by spectral unmixing of the MSOT data. Together, our study for the first time demonstrated the capability of DGE-MSOT in assessing vascular hemodynamics of tumors.

Intraoperative Imaging in Hepatopancreatobiliary Surgery

Hepatopancreatobiliary surgery belongs to one of the most complex fields of general surgery. An intricate and vital anatomy is accompanied by difficult distinctions of tumors from fibrosis and inflammation; the identification of precise tumor margins; or small, even disappearing, lesions on currently available imaging. The routine implementation of ultrasound use shifted the possibilities in the operating room, yet more precision is necessary to achieve negative resection margins. Modalities utilizing fluorescent-compatible dyes have proven their role in hepatopancreatobiliary surgery, although this is not yet a routine practice, as there are many limitations. Modalities, such as photoacoustic imaging or 3D holograms, are emerging but are mostly limited to preclinical settings. There is a need to identify and develop an ideal contrast agent capable of differentiating between malignant and benign tissue and to report on the prognostic benefits of implemented intraoperative imaging in order to navigate clinical translation. This review focuses on existing and developing imaging modalities for intraoperative use, tailored to the needs of hepatopancreatobiliary cancers. We will also cover the application of these imaging techniques to theranostics to achieve combined diagnostic and therapeutic potential.

Simultaneous Detection of Multiple Tumor-targeted Gold Nanoparticles in HER2-Positive Breast Tumors Using Optoacoustic Imaging

Purpose To develop optoacoustic, spectrally distinct, actively targeted gold nanoparticle-based near-infrared probes (trastuzumab [TRA], TRA-Aurelia-1, and TRA-Aurelia-2) that can be individually identifiable at multispectral optoacoustic tomography (MSOT) of human epidermal growth factor receptor 2 (HER2)-positive breast tumors. Materials and Methods Gold nanoparticle-based near-infrared probes (Aurelia-1 and 2) that are optoacoustically active and spectrally distinct for simultaneous MSOT imaging were synthesized and conjugated to TRA to produce TRA-Aurelia-1 and 2. Freshly resected human HER2-positive (n = 6) and HER2-negative (n = 6) triple-negative breast cancer tumors were treated with TRA-Aurelia-1 and TRA-Aurelia-2 for 2 hours and imaged with MSOT. HER2-expressing DY36T2Q cells and HER2-negative MDA-MB-231 cells were implanted orthotopically into mice (n = 5). MSOT imaging was performed 6 hours following the injection, and the Friedman test was used for analysis. Results TRA-Aurelia-1 (absorption peak, 780 nm) and TRA-Aurelia-2 (absorption peak, 720 nm) were spectrally distinct. HER2-positive human breast tumors exhibited a significant increase in optoacoustic signal following TRA-Aurelia-1 (28.8-fold) or 2 (29.5-fold) (P = .002) treatment relative to HER2-negative tumors. Treatment with TRA-Aurelia-1 and 2 increased optoacoustic signals in DY36T2Q tumors relative to those in MDA-MB-231 controls (14.8-fold, P < .001; 20.8-fold, P < .001, respectively). Conclusion The study demonstrates that TRA-Aurelia 1 and 2 nanoparticles operate as a spectrally distinct HER2 breast tumor-targeted in vivo optoacoustic agent. Keywords: Molecular Imaging, Nanoparticles, Photoacoustic Imaging, Breast Cancer Supplemental material is available for this article. © RSNA, 2023.

Abstract 362: Development of PEP3-IR750 probe to identify adipose tissue and cachexia in murine models

Background Cachexia is a multifactorial adipose and muscle wasting disease that is frequently identified in patients with cancer. Cachexia results from increased lipolysis, proteolysis, inflammation, and tumor/host secreted cytokines. Unfortunatly, cachexia is often identified in the clinic at late stages after substantial adipose and muscle loss has occured. Currently, the identification of cachexia in its adipose-wasting stages is difficult due to the lack of a diagnostic imaging tool that easily, objectively, and reproducibly monitors the loss of adipose tissue. Objective identification of fat stores could be used for the early identification and monitoring of cachexia.

Methods We used Fmoc chemistry to synthesize a peptide that binds to fat, i.e. PEP3, CPATAEPC, and scrambled control peptide, AQYLNPS. Following microwave peptide synthesis, we lyophilized, purified, and conjugated the peptides to the Hilyte Fluor750 succinimidyl ester using NHS reaction. Excess dye was removed using dialysis in water. IR750-PEP3 probe was assessed using HPLC and spectroscopy to determine the probe concentrations. Sixty nanomoles of probe reconstituted in 200 µL PBS (pH 7.4). Ex vivo interscapular, perirenal, and omental fat and control muscle tissues were incubated with 20 µM IR750-PEP3 and scrambled probes for 1 h in a 6-well plate, tissues washed with PBS to remove unbound probe, and imaged using near infrared fluorescence. In vivo testing assessed, 60 nmol intravenous injection into healthy female mice. Mice were imaged using MSOT 4 h post injection, images were reconstructed and spectrally unmixed based upon the spectrums of brown fat and IR750 dye. Parametric maps were generated via MATLAB to identify distributions of fat and injected probes. Secondary confirmation of probe biodistribution was conducted using NIR fluorescence of excised tissues.

Results Following injecting 60 nmol of IR750-PEP3, MSOT images confirmed that the PEP3-IR750 dye localized to areas of fat in the interscapular, and perirenal areas in vivo compared to scrambled control (p=0.05, Mann-Whitney U Test). The higher capability of PEP3-IR750 to localize to fat tissue was further confirmed by ex vivo evaluation of PEP3-IR750 and scramble probes-IR750 (p=0.05, Mann-Whitney U Test). Notably, there was a complete lack of signal in the control muscle tissue.

Conclusion PEP3-IR750 can specifically identify fat in mice, and our data supports its potential use in the early identification of cachexia.

Citation Format: Sophia Chakrabarty, Zheng Han, Lacey R. McNally. Development of PEP3-IR750 probe to identify adipose tissue and cachexia in murine models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 362.

Abstract 2390: Claudin-4 probe identifies triple negative breast cancer using multispectral optoacoustic tomography

Background: Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. The cancer is known for the lack of estrogen and her2 receptors. TNBC has a 5-year survival rate of 77% as for the other breast cancers averaging out at 93%. The CL-750 probes are made to identify the claudin-4 that is expressed in TNBC, making it easy to identify the cancer quickly so we can treat quickly.

Methods: TNBC, aggressive pancreatic and kidney cancer cell lines were used to assess the expression of claudin-4 via western blot. Based upon the C-terminal fragment of Clostridium perfingens, we synthesized a 30 aa peptide. CL peptide was conjugated to amine reactive HiLite 750 nm fluorescent dye. The CL-750 probes were purified using dialysis to remove unattached dye. MDA-MB-468 (TNBC), MDA-MB-231 (TNBC), S2VP10 (pancreatic), and 293 (kidney) cells were incubated with CL-750 probes for 30 minutes and evaluated with near infrared-fluorescence using Odyssey imaging software. Using the treated cells were then scraped into agar tissue mimicking phantoms, the probes were assessed for optoacoustic activity using the MSOT (Multispectral optoacoustic tomography).

Results: Using western blot to show expression of claudin-4 within cell lines the S2VP10 pancreatic (positive control) showed the most expression of claudin-4, while the 293 kidney cells showed a lesser amount. Both MDA-MB-468 and MDA-MB-231 TNBC cells showed the lowest amount of claudin-4 nonetheless both showed enough to continue with experiments. Cell line S2VP10 showed an extreme amount of binding to probe, while as the probe also bound to both smaller amount of claudin positive breast cancer cell line (MDA-MB-231) and larger amount of claudin breast cancer cell line (MDA-MB-468). Both CL-Short-750 and CL-Long-750 showed signal using MSOT. The CL-Long-750 showed 2x as much signal as CL-Short-750 making the Cl-long-750 probe more efficient in identifying claudin positive cell TNBC (p&lt;0.05).

Conclusion: Both CL-750-probes have the capability of identifying claudin-4 positive cell lines, but CL-Long-750 was more effective and had greater binding.

Citation Format: Laycee Parsons, William M. MacCuaig, Lacey R. McNally. Claudin-4 probe identifies triple negative breast cancer using multispectral optoacoustic tomography [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2390.

Abstract 2379: Tunable squaraine dyes as contrast agents for image guided surgery with optoacoustic imaging

Surgical removal of cancers results in the most favorable patient outcomes. Resection margins may be tumor-positive in up to 70% of cases depending on cancer type, representing an unmet clinical need. Image-guided surgery often utilizes fluorescent dyes such as IR 800CW, but are limited to 8mm of depth and result in potential false-positive signal due to high blood binding. To overcome limitations, we are developing new contrast agents for Multispectral optoacoustic tomography (MSOT)-guided surgery to allow for greater depth of penetration and future potential of multiplexing of agents.To generate squaraine contrast agents, we prepared heterocyclic salts side arms refluxed with squaric acid to form 6 different compounds. The compounds differ only in halogenation of heterocyclic salts and inclusion of dual trimethylpropylammonium (TMAB) pendant groups. All squaraines were confirmed with NMR/spectrometry. MSOT and fluorescence were utilized to investigate the in vitro optoacoustic/fluorescence activity of the compounds. Computational modeling of squaraines through density functional theory was used to reveal quantum properties of the compounds including vibrational entropy, oscillator strength, and dipole moment. Compounds were administered orally in a murine model to confirm visualization capability with MSOT and fluorescence.Squaraine dyes functionalized with heavier halogens (Br, Cl) exhibited higher optoacoustic activity than dyes with less heavy (F), or without halogen. Specifically, TMAB/Br functionalized squaraine exhibited 2.12 optoacoustic units in vivo, compared to 0.81, 0.58, and 0.44 for Cl, F, and no halogen compounds, respectively (all p&lt;0.001). Inclusion of the dual TMAB groups increased optoacoustic activity. When comparing Br compounds with/without TMAB, the TMAB functionalized compound outperformed the counterpart significantly, (2.12 a.u. vs. 0.21 a.u., p&lt;0.001). Fluorescence intensity in vivo between TMAB/Br and TMAB/Cl compounds were not significantly different (3.07E9 vs. 2.81E9 counts), indicating that fluorescence signal does not necessarily predict optoacoustic activity. Computational modeling revealed heavy halogens and TMAB functionalized dyes exhibit increased vibrational entropy, oscillator strength, dipole moment, and presence of right-shifted absorbance peaks. In vivo studies in a murine model confirmed that heavy halogen and TMAB functionalized dyes were visible in the gastrointestinal tract using both MSOT and fluorescence imaging.Image-guided surgical removal of cancer yields best patient outcomes, but is currently limited by blood binding and imaging depth. MSOT is a potential candidate, but lack of contrast has hurt clinical application. This study focused on synthesis and evaluation of squaraine compounds as potential optoacoustic contrast to expand the potential of MSOT in a clinical setting for image guided surgery for cancer.

Citation Format: William M. MacCuaig, Carly Wickizer, Maged Henary, Yihan Shao, Barish H. Edil, Ajay Jain, William E. Grizzle, Lacey R. McNally. Tunable squaraine dyes as contrast agents for image guided surgery with optoacoustic imaging [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2379.

Innovative Imaging Techniques Used to Evaluate Borderline-Resectable Pancreatic Adenocarcinoma

A diagnosis of pancreatic cancer carries a 5-y survival rate of less than 10%. Furthermore, the detection of pancreatic cancer occurs most often in later stages of the disease due to its location in the retroperitoneum and lack of symptoms (in most cases) until tumors become more advanced. Once diagnosed, cross-sectional imaging techniques are heavily utilized to determine the tumor stage and the potential for surgical resection. However, a major determinant of resectability is the extent of local vascular involvement of the mesenteric vessels and critical tributaries; current imaging techniques have limited capacity to accurately determine vascular involvement. Surrounding inflammation and fibrosis can be difficult to discriminate from viable tumor, making determination of the degree of vascular involvement unreliable. New innovations in fluorescence and optoacoustic imaging techniques may overcome these limitations and make determination of resectability more accurate. These imaging modalities are able to more clearly discern between viable tumor tissue and non-neoplastic inflammation or desmoplasia, allowing clinicians to more reliably characterize vascular involvement and develop individualized treatment plans for patients. This review will discuss the current imaging techniques used to diagnose pancreatic cancer, the barriers that current techniques raise to accurate staging, and novel fluorescence and optoacoustic imaging techniques that may provide more accurate clinical staging of pancreatic cancer.

Advances in Imaging of Inflammation, Fibrosis, and Cancer in the Gastrointestinal Tract

Gastrointestinal disease is prevalent and broad, manifesting itself in a variety of ways, including inflammation, fibrosis, infection, and cancer. However, historically, diagnostic technologies have exhibited limitations, especially with regard to diagnostic uncertainty. Despite development of newly emerging technologies such as optoacoustic imaging, many recent advancements have focused on improving upon pre-existing modalities such as ultrasound, computed tomography, magnetic resonance imaging, and endoscopy. These advancements include utilization of machine learning models, biomarkers, new technological applications such as diffusion weighted imaging, and new techniques such as transrectal ultrasound. This review discusses assessment of disease processes using imaging strategies for the detection and monitoring of inflammation, fibrosis, and cancer in the context of gastrointestinal disease. Specifically, we include ulcerative colitis, Crohn's disease, diverticulitis, celiac disease, graft vs. host disease, intestinal fibrosis, colorectal stricture, gastric cancer, and colorectal cancer. We address some of the most recent and promising advancements for improvement of gastrointestinal imaging, including unique discussions of such advancements with regard to imaging of fibrosis and differentiation between similar disease processes.

Abstract 2458: Comparing influences of active targeting and nanoparticle size on tumor specificity in pancreatic adenocarcinoma

Purpose: While nanoparticles are widely studied as potential theranostic treatments for cancer, weak tumor specificity has hindered clinical translation. Features that contribute to tumor specificity are historically controversial, particularly when using clinically relevant models. Aggressive cancers, such as pancreatic ductal adenocarcinoma (PDAC), stand to benefit from development of highly specific nanoparticles as a theranostic drug delivery system. This work evaluates active targeting and nanoparticle size, in a silica-based nanoparticle for specific accumulation and release of contrast agent within an orthotopically implanted tumor.

Methods: Mesoporous silica nanoparticles (MSNs) were synthesized with wormhole-like pores using a silica precursor to coat a surfactant scaffold. Chitosan was attached to MSN surface as a pH-responsive gatekeeper for encapsulated agents. A series of acidification and basification procedures resulted in loading of photoacoustic contrast agent IR780 within MSN pores. MSNs were further functionalized for attachment of V7 peptide to target aggressive and acidic pancreatic cancer. pH-sensitivity and tumor specificity/uptake was validated using an in vitro PDAC cell model (S2VP10L) prior to implantation and assessment in an animal model. Functionalized MSNs were intravenously injected into athymic mice with orthotopically implanted PDAC tumors. Near infrared fluorescence and optoacoustic imaging were used to evaluate the biodistribution of MSNs subsequent to treatment.

Results: Zeta potential, DLS, and TEM were utilized to show three differently sized MSNs of 26, 45, and 73 nm and confirm conjugation of chitosan and V7 peptide. Dye-release assays indicated significantly increased agent release from MSNs in acidic pH (~90%) compared to biological pH (~15%) (p=0.001). Treatment of PDAC cell line with MSNs showed highest uptake and specificity with actively targeted 26nm particles and that all actively targeted MSNs exhibited greater specificity than all passively targeted MSNs (p&lt;0.05). In vivo results utilizing optoacoustic imaging confirmed that active targeting produces a stronger tumor specificity, and that nanoparticle size has a secondary influence in which the smaller, 26 nm MSNs, showed optimal specificity (p&lt;0.001). Ex vivo evaluation of organs was in agreement with in vivo observations.

Conclusion: Active targeting outperforms nanoparticle size for facilitation of tumor-specific uptake in an acidic PDAC murine model. Active targeting was necessary for high accumulation of MSNs and contrast agent in the tumor. Nanoparticle size had a secondary, but notable influence on tumor uptake in which smaller sized MSNs resulted in higher tumor specificity.

Citation Format: William M. MacCuaig, Abhilash Samykutty, Molly McNally, Ajay Jain, William E. Grizzle, Lacey R. McNally. Comparing influences of active targeting and nanoparticle size on tumor specificity in pancreatic adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2458.

Abstract 300: Matrix metalloproteinase-9 responsive active targeted silica nanoparticles for pancreatic cancer detection by multispectral optoacoustic tomography

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is the most lethal disease and the leading cause of cancer death worldwide. The survival rate of patients with this form of cancer is about 8%. The physiological barrier of the tumor microenvironment composed of a dense stroma and disorganized blood vessels creates a barrier for early identification and treatment of this deadly disease. In recent years, nanoparticle-based controlled delivery systems were developed to exploit the pathophysiology of biological systems such as acidic tumor microenvironment or the altered tumor-specific enzymes to improve the diagnosis and treatment efficacy. Here, we demonstrate the collagenase IV-mediated tumor site-selective release of the IR-780 imaging probe from the M-Ge-SDC1 nanoparticles, revealing the feasibility of the collagenase IV (MMP-9) responsive target specificity for diagnosing pancreatic cancer by multispectral optoacoustic tomography (MSOT) imaging.

Methods: Mesoporous silica nanoparticles (MSN) with wormhole pore topology were synthesized and were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The surface of MSN was conjugated with Gelatin-A to obtain M-Ge. The M-Ge particles were loaded with propidium Iodide (PI) or IR780 infrared imaging dye. The M-Ge surface was further conjugated with Syndecan-1 (SDC1) to improve the target specificity to release imaging cargo from the nanoparticles. Female athymic mice were orthotopically implanted with S2VP10 tumor cells. After a week of tumor implantation, mice were intravenously injected with M-Ge-SDC1 nanoparticles containing IR780 dye and were imaged with MSOT and AMI.

Results: In the current study, Mesoporous silica nanoparticles with 27 nm diameter were synthesized. The Gelatin-A crosslinking on the surface of MSN particles as a gatekeeper was developed that could degrade upon contact with collagenase IV in the tumor microenvironment. The conjugation of SDC1 further improved the tumor specificity. The athymic mice orthotopically implanted with S2VP10 cells closely resemble human PDAC. Our results demonstrated that intravenous delivery of M-Ge-SDC1 nanoparticles could enzymatically degrade (MMP-9) and release IR780 at the tumor site and conjugation of SDC1 further improved the tumor specificity to detect the orthotopically implanted pancreatic tumors (p&lt;0.0001,n=5).

Conclusion: Due to the lack of effective screening tools, PDAC has the lowest survival rate and limited therapeutic efficacy for current FDA-approved drugs compared to other malignancies. Innovative technologies to develop engineered nanoparticles with active targeting moiety and dynamic imaging technology can overcome these limitations. Implementing such systems can enhance PDAC detection that can be translated into the clinic to improve health care.

Citation Format: Abhilash Samykutty, Molly McNally, William M. MacCuaig, Jordan Hagood, Girish Mishra, Barish H. Edil, William E. Grizzle, Lacey R. McNally. Matrix metalloproteinase-9 responsive active targeted silica nanoparticles for pancreatic cancer detection by multispectral optoacoustic tomography [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 300.

Toxicity Assessment of Mesoporous Silica Nanoparticles upon Intravenous Injection in Mice: Implications for Drug Delivery

Nanoparticles are popular tools utilized to selectively deliver drugs and contrast agents for identification and treatment of disease. To determine the usefulness and translational potential of mesoporous silica nanoparticles (MSNs), further evaluations of toxicity are required. MSNs are among the most utilized nano-delivery systems due to ease of synthesis, pore structure, and functionalization. This study aims to elucidate toxicity as a result of intravenous injection of 25 nm MSNs coated with chitosan (C) or polyethylene glycol (PEG) in mice. Following acute and chronic injections, blood was evaluated for standard blood chemistry and complete blood count analyses. Blood chemistry results primarily indicated that no abnormalities were present following acute or chronic injections of MSNs, or C/PEG-coated MSNs. After four weekly administered treatments, vital organs showed minor exacerbation of pre-existing lesions in the 35KPEG-MSN and moderate exacerbation of pre-existing lesions in uncoated MSN and 2KPEG-MSN treatment groups. In contrast, C-MSN treatment groups had minimal changes compared to controls. This study suggests 25 nm MSNs coated with chitosan should elicit minimal toxicity when administered as either single or multiple intravenous injections, but MSNs coated with PEG, especially 2KPEG may exacerbate pre-existing vascular conditions. Further studies should evaluate varying sizes and types of nanoparticles to provide a better overall understanding on the relation between nanoparticles and in vivo toxicity.

Differential expression of microRNA between triple negative breast cancer patients of African American and European American descent

There are racial disparities in the outcome of triple negative breast cancer (TNBC) patients between women of African ancestry and women of European ancestry, even after accounting for lifestyle, socioeconomic and clinical factors. MicroRNA (miRNA) are non-coding molecules whose level of expression is associated with cancer suppression, proliferation and drug resistance; therefore, these have potential for biomarker applications in cancers including TNBC. Historically, miRNAs up-regulated in African American (AA) patients have received less attention than for patients of European ancestry. Using laser capture microdissection (LCM) to acquire ultrapure tumor cell samples, miRNA expression was evaluated in 15 AA and 15 European American (EA) TNBC patients. Tumor sections were evaluated using RNA extraction followed by miRNA analysis and profiling. Results were compared based on ethnicity and method of tissue fixation. miRNAs that showed high differential expression in AA TNBC patients compared to EA included: miR-19a, miR-192, miR-302a, miR-302b, miR-302c, miR-335, miR-520b, miR-520f and miR-645. LCM is a useful technique for isolation of tumor cells. We found a greater abundance of RNA in frozen samples compared to formalin fixed, paraffin embedded samples. miRNA appears to be a useful biomarker for TNBC to improve diagnosis and treatment.

Active Targeting Significantly Outperforms Nanoparticle Size in Facilitating Tumor-Specific Uptake in Orthotopic Pancreatic Cancer

Nanoparticles are widely studied as theranostic vehicles for cancer; however, clinical translation has been limited due to poor tumor specificity. Features that maximize tumor uptake remain controversial, particularly when using clinically relevant models. We report a systematic study that assesses two major features for the impact on tumor specificity, i.e., active vs passive targeting and nanoparticle size, to evaluate relative influences in vivo. Active targeting via the V7 peptide is superior to passive targeting for uptake by pancreatic tumors, irrespective of nanoparticle size, observed through in vivo imaging. Size has a secondary effect on uptake for actively targeted nanoparticles in which 26 nm nanoparticles outperform larger 45 and 73 nm nanoparticles. Nanoparticle size had no significant effect on uptake for passively targeted nanoparticles. Results highlight the superiority of active targeting over nanoparticle size for tumor uptake. These findings suggest a framework for optimizing similar nonaggregate nanoparticles for theranostic treatment of recalcitrant cancers.

Mesoporous Silica Nanoparticles: Properties and Strategies for Enhancing Clinical Effect

Due to the theragnostic potential of mesoporous silica nanoparticles (MSNs), these were extensively investigated as a novel approach to improve clinical outcomes. Boasting an impressive array of formulations and modifications, MSNs demonstrate significant in vivo efficacy when used to identify or treat myriad malignant diseases in preclinical models. As MSNs continue transitioning into clinical trials, a thorough understanding of the characteristics of effective MSNs is necessary. This review highlights recent discoveries and advances in MSN understanding and technology. Specific focus is given to cancer theragnostic approaches using MSNs. Characteristics of MSNs such as size, shape, and surface properties are discussed in relation to effective nanomedicine practice and projected clinical efficacy. Additionally, tumor-targeting options used with MSNs are presented with extensive discussion on active-targeting molecules. Methods for decreasing MSN toxicity, improving site-specific delivery, and controlling release of loaded molecules are further explained. Challenges facing the field and translation to clinical environments are presented alongside potential avenues for continuing investigations.

Diabetes, Obesity, and Inflammation: Impact on Clinical and Radiographic Features of Breast Cancer

Obesity, diabetes, and inflammation increase the risk of breast cancer, the most common malignancy in women. One of the mainstays of breast cancer treatment and improving outcomes is early detection through imaging-based screening. There may be a role for individualized imaging strategies for patients with certain co-morbidities. Herein, we review the literature regarding the accuracy of conventional imaging modalities in obese and diabetic women, the potential role of anti-inflammatory agents to improve detection, and the novel molecular imaging techniques that may have a role for breast cancer screening in these patients. We demonstrate that with conventional imaging modalities, increased sensitivity often comes with a loss of specificity, resulting in unnecessary biopsies and overtreatment. Obese women have body size limitations that impair image quality, and diabetes increases the risk for dense breast tis-sue. Increased density is known to obscure the diagnosis of cancer on routine screening mammography. Novel molecu-lar imaging agents with targets such as estrogen receptor, human epidermal growth factor receptor 2 (HER2), pyrimi-dine analogues, and ligand-targeted receptor probes, among others, have potential to reduce false positive results. They can also improve detection rates with increased resolution and inform therapeutic decision making. These emerg-ing imaging techniques promise to improve breast cancer diagnosis in obese patients with diabetes who have dense breasts, but more work is needed to validate their clinical application.

An integrated model of N6-methyladenosine regulators to predict tumor aggressiveness and immune evasion in pancreatic cancer

BACKGROUND

N6-methyladenosine (m6A) is the most abundant mRNA modification. Whether m6A regulators can determine tumor aggressiveness and risk of immune evasion in pancreatic ductal adenocarcinoma (PDAC) remains unknown.

METHODS

An integrated model named "m6Ascore" is constructed based on RNA-seq data of m6A regulators in PDAC. Association of m6Ascore and overall survival is validated across several different datasets. Overlaps of m6Ascore and established molecular classifications of PDAC is examined. Immune infiltration, enriched pathways, somatic copy number alterations (SCNAs), mutation profiles and response to immune checkpoint inhibitors are compared between m6Ascore-high and m6Ascore-low tumors.

FINDINGS

m6Ascore is associated with dismal overall survival and increased tumor recurrence in PDAC as well as several other solid tumors including colorectal cancer and breast cancer. Basal-like (Squamous) PDAC has higher m6Ascore than that in the classical PDAC. Mechanism study showed m6Ascore-high tumors are characterized with reduced immune infiltration and T cells exhaustion. Meanwhile, m6Ascore is associated with genes regulating cachexia and chemoresistance in PDAC. Furthermore, distinct SCNAs patterns and mutation profiles of KRAS and TP53 are present in m6Ascore-high tumors, indicating immune evasion. m6Ascore-low tumors have higher response rates to immune checkpoint inhibitors (ICIs).

INTERPRETATION

These findings indicate m6Ascore can predict aggressiveness and immune evasion in pancreatic cancer. This model has implications for pancreatic cancer prognosis and treatment response to ICIs.

FUNDING

This work was supported in part by National Institutes of Health (NIH) grants to M. Li (R01 CA186338, R01 CA203108, R01 CA247234 and the William and Ella Owens Medical Research Foundation) and NIH/National Cancer Institute Q39 award P30CA225520 to Stephenson Cancer Center.

Improved pentamethine cyanine nanosensors for optoacoustic imaging of pancreatic cancer

Optoacoustic imaging is a new biomedical imaging technology with clear benefits over traditional optical imaging and ultrasound. While the imaging technology has improved since its initial development, the creation of dedicated contrast agents for optoacoustic imaging has been stagnant. Current exploration of contrast agents has been limited to standard commercial dyes that have already been established in optical imaging applications. While some of these compounds have demonstrated utility in optoacoustic imaging, they are far from optimal and there is a need for contrast agents with tailored optoacoustic properties. The synthesis, encapsulation within tumor targeting silica nanoparticles and applications in in vivo tumor imaging of optoacoustic contrast agents are reported.

Molecular Imaging of Inflammatory Disease

Inflammatory diseases include a wide variety of highly prevalent conditions with high mortality rates in severe cases ranging from cardiovascular disease, to rheumatoid arthritis, to chronic obstructive pulmonary disease, to graft vs. host disease, to a number of gastrointestinal disorders. Many diseases that are not considered inflammatory per se are associated with varying levels of inflammation. Imaging of the immune system and inflammatory response is of interest as it can give insight into disease progression and severity. Clinical imaging technologies such as computed tomography (CT) and magnetic resonance imaging (MRI) are traditionally limited to the visualization of anatomical information; then, the presence or absence of an inflammatory state must be inferred from the structural abnormalities. Improvement in available contrast agents has made it possible to obtain functional information as well as anatomical. In vivo imaging of inflammation ultimately facilitates an improved accuracy of diagnostics and monitoring of patients to allow for better patient care. Highly specific molecular imaging of inflammatory biomarkers allows for earlier diagnosis to prevent irreversible damage. Advancements in imaging instruments, targeted tracers, and contrast agents represent a rapidly growing area of preclinical research with the hopes of quick translation to the clinic.

Development of Multispectral Optoacoustic Tomography as a Clinically Translatable Modality for Cancer Imaging

The use of optoacoustic imaging takes advantage of the photoacoustic effect to generate high-contrast, high-resolution medical images at penetration depths of up to 5 cm. Multispectral optoacoustic tomography (MSOT) is a type of optoacoustic imaging system that has seen promising preclinical success with a recent emergence into the clinic. Multiwavelength illumination of tissue allows for the mapping of multiple chromophores, which are generated endogenously or exogenously. However, translation of MSOT to the clinic is still in its preliminary stages. For successful translation, MSOT requires refinement of probes and data-acquisition systems to tailor to the human body, along with more intuitive, real-time visualization settings. The possibilities of optoacoustic imaging, namely MSOT, in the clinic are reviewed here. ©RSNA, 2020.

Abstract 2790: Evaluation of S100A9 targeted nanoparticles containing rapamycin to treat pancreatic adenocarcinoma

Despite Pancreatic cancer being expected to contribute to only 3% of new cancer cases in both males and females in 2019, it is expected to cause an estimated 45,750 deaths making it the third highest contributor to cancer deaths. This is due to the low survivability associated with pancreatic cancer which has a 5-year survival rate of only 9%. In order to address the poor prognosis common with pancreatic cancer, biomarkers are being used to create therapies targeted to specific cancer cells. The S100A8/A9 complex is a heterodimer, known for modulating the inflammatory response, and it is upregulated in a variety of cancers including pancreatic cancers. For this reason, we selected it as a targeting agent to deliver Rapamycin to pancreatic cancer cells via a mesoporous silica-encased gold nanorod (MS-GNR). The use of this nanoparticle allows an anticancer molecule to be encapsulated within the mesoporous silica matrix by further encapsulation of the nanoparticle with the pH sensitive polymer chitosan. A low pH tumor microenvironment induces relaxation of the chitosan surrounding this chitosan-capped mesoporous silica gold nanorod (CMG) allowing for the anticancer molecule to be released only in cancer cells. The gold nanorod at the core of this enables these nanoparticles to be imaged in real time via Multispectral Optoacoustic Tomography (MSOT). Using these tools, we linked S100A9 to a mesoporous silica-encased gold nanorod which contained Rapamycin held in via the chitosan polymer (S100A9-Rap-CMG). MSOT imaging revealed a strong uptake in S2013Q and MiaPaca pancreatic cancer cells. Further tests showed that at a pH 6.8 S100A9-Rap-CMG treatment resulted in an increase in cell death by 69% compared to treatment at physiologic pH of 7.4 by the S100A9-Rap-CMG's which did not induce cell death. This data indicates the feasibility of S100A9 as a targeting agent for pancreatic cancer cells and the potential benefits of nano-drug delivery of Rapamycin to treat pancreatic adenocarcinoma. The ultimate benefit of the nano-drug delivery includes both increased tumor targeting and mitigating premature drug release and offsite delivery.

Citation Format: Karl Thomas, Molly McNally, Abhilash Samykutty, Lacey R. McNally. Evaluation of S100A9 targeted nanoparticles containing rapamycin to treat pancreatic adenocarcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2790.

The neutral red assay can be used to evaluate cell viability during autophagy or in an acidic microenvironment in vitro

Harsh conditions within the tumor microenvironment, such as hypoxia and extracellular acidic pH (pH_e), inactivate some chemotherapies, which results in limited or no cytotoxicity. Standard MTT, ATPlite and protease assays that are used to determine the potency of newly developed drugs often give erroneous results when applied under hypoxic or acidic conditions. Therefore, development of a cytotoxicity assay that does not yield false positive or false negative results under circumstances of both hypoxia and acidic pH_e is needed. We evaluated currently used cell viability assays as well as neutral red staining to assess viability of ovarian and pancreatic cancer cells grown in an acidic pH_e microenvironment after treatment with carboplatin, gemcitabine or chloroquine. We validated cell viability using western blotting of pro-caspase-9 and cleaved-caspase-9, and LC3-I and - II. Standard cell viability assays indicated cell viability accurately at pH_e 7.4, but was not correlated with induction of apoptosis or autophagy at acidic pH_e. By contrast, our modified neutral red assay detected cell viability accurately over a range of pH_e as demonstrated by its correlation with induction of apoptosis and autophagy. Neutral red staining is effective for evaluating the effect of chemotherapeutic agents on cell viability under acidic pH_e or hypoxic conditions.

Incidence and Survival by Human Epidermal Growth Factor Receptor 2 Status in Young Women With Stage I-III Breast Cancer: SEER, 2010-2016

BACKGROUND

Young premenopausal women with breast cancer often experience more aggressive disease biology and poorer survival than older women. Diagnostic and therapeutic advances, including human epidermal growth factor receptor 2 (HER2)-directed therapy, may lessen treatment burden and improve survival for these young women, but contemporary incidence and survival data by HER2 status are limited.

PATIENTS AND METHODS

We identified women aged 20-49 years (n = 68,530) diagnosed with stage I-III breast cancer during 2010-2016 from the United States Surveillance, Epidemiology, and End Results 18 registries database. Age-adjusted average annual percent changes in incidence (diagnosis 2010-2016) and 5-year Kaplan-Meier survival curves (diagnosis 2010-2015) were estimated by HER2 and hormone receptor (HR) status and stratified independently by cancer stage and race/ethnicity.

RESULTS

With increasing age decade, proportions of HER2-/HR+ cancer increased, whereas proportions of HER2+/HR+, HER2+/HR-, and HER2-/HR- decreased. The greatest increases in incidence during 2010-2016 were observed for HER2+ among women aged 20-49 years and HER2-/HR- among women aged 20-29 years. Incidence decreased for HER2-/HR- among women aged 40-49 years. Five-year survival was lowest for HER2-/HR- status compared to other receptor-based subtypes among women aged 20-49 years. HER2+ status was more beneficial for 5-year survival than HR+ status among women aged 20-29 years, with the opposite observed among women aged 30-49 years, particularly those aged 40-49 years.

CONCLUSION

HER2+ breast cancer increased among premenopausal women and was also associated with higher early survival within each HR status. HER2-/HR- cancer also increased among women aged 20-29 years and was associated with lower early survival. Our contemporary data provide important insights to help inform preventive and therapeutic strategies for premenopausal women.

Squaraine Dyes: Molecular Design for Different Applications and Remaining Challenges

Squaraine dyes are a class of organic dyes with strong and narrow absorption bands in the near-infrared. Despite high molar absorptivities and fluorescence quantum yields, these dyes have been less explored than other dye scaffolds due to their susceptibility to nucleophilic attack. Recent strategies in probe design including encapsulation, conjugation to biomolecules, and new synthetic modifications have seen squaraine dyes emerging into the forefront of biomedical imaging and other applications. Herein, we provide a concise overview of (1) the synthesis of symmetrical and unsymmetrical squaraine dyes, (2) the relationship between structure and photophysical properties of squaraine dyes, and (3) current applications of squaraine dyes in the literature. Given the recent successes at overcoming the limitations of squaraine dyes, they show high potential in biological imaging, in photodynamic and photothermal therapies, and as molecular sensors.

Abstract P3-06-04: Tumor specific cargo release in ex vivo patient samples and murine models of triple negative breast cancer by a pH-targeted nanoparticle: V3-RUBY

Background: Triple negative breast cancer (TNBC), unlike other breast cancer subtypes, lacks a specific targetable receptor. As such tumor specific delivery, which can limit off-target effects of anti-neoplastic therapies, has been an unmet clinical need in treating this aggressive breast cancer subtype. To address this need, we exploited the tumor hallmark of an acidic microenvironment and developed a pH targeted nanoparticle by conjugation of the V3 pH specific peptide on a wormhole pore mesoporous silica nanoparticles (V3-RUBY) and assessed the ability of V3-RUBY to specifically release cargo in ex vivo patient samples and in orthotopically implanted TNBC tumors as detect by multispectral optoacoustic imaging technology (MSOT).

Methods: The silica nanoparticles with wormhole pore architecture were synthesized by sol-gel chemistry and characterized by transmission electron microscopy (TEM), zeta potential, and dynamic light scattering (DLS). The surface base particle was crosslinked with a gatekeeper molecule, chitosan. Further targeting of the particle using V3 pHLIP (low insertion peptide), resulted in the V3-RUBY nanoparticle which allows for pH-sensitive cargo release. The particle was loaded with imaging dye to assess tumor specificity. Fresh ex vivo TNBC patient tumor tissues were resected and rapidly treated with V3-RUBY containing propodium iodide (PI) to evaluate tumor uptake of V3-RUBY and cargo release within the tumor cells, as measured by the red fluorescence of PI when bound to nucleic acids. (PI independently cannot cross cell membranes.) In vivo, female athymic mice were implanted with MDA-MB-468 breast cancer cells by the mammary fat pad injection. Once the tumor reached 3mm in size, athymic mice were intravenously injected with V3-RUBY nanoparticles carrying IR780 infrared imaging dye and were imaged with MSOT inVision 512TF.

Results: The RUBY nanoparticle with wormhole pores was 27 nm diameter. The dual targeting approach of a nanoparticle with V3 targeting peptide and chitosan demonstrated pH specificity around tumor pH. In ex vivo patient TNBC samples, V3-RUBY demonstrated active targeting and dye release at pH 6.8, which approximated the pH measured at surgical tumor removal, in 10 fresh patient samples compared to pH 7.4 controls (p&lt;0.0001, N=10) (Table). There was a non-significant trend towards lower uptake in histological grade 2 tumors, relative to grade 3 tumors. In the murine models, IR780 uptake in the MDA-MB-468 tumors measured 23.2 a.u (arbitrary units) and was 3.1, a.u. in the liver and 0.9 a.u. in the kidneys (p &lt;0.0001, N=5). Tumor accumulation in the MDA-MB-468 model was significantly increased compared to both liver and kidneys (p=0.0002 and p=0.0003).

Conclusion: The tumor-specific release of payload by V3-RUBY suggests the potential of a pH specific target in TNBC, with such a nanoparticle holding promise to deliver both diagnostic and therapeutic cargo directly to the tumor and limit off-target toxicity. Future translation of these technologies could have promise in TNBC, as well as other high-grade breast cancer subtypes and expand treatment options in this challenging area of oncology.

TablePatientBreast Cancer SubtypeTumor GradePathologic StagePI Uptake (a.u.) pH 6.8PI Uptake (a.u.) 7.41TNBC3ypT3N3a33.20.82TNBC3ypT2N038.41.53TNBC3ypT4bN1a36.81.74TNBC3T1bN022.40.85TNBC2T1cN021.80.86TNBC2ypT0N021.50.67TNBC3ypT1aN2a22.00.48TNBC3ypT4dN239.52.19TNBC3T2N2a31.52.210TNBC3T2N1a32.21.8

Citation Format: Alexandra Thomas, Akiko Chiba, Abhilash Samykutty, Molly W. McNally, Lacey R. McNally. Tumor specific cargo release in ex vivo patient samples and murine models of triple negative breast cancer by a pH-targeted nanoparticle: V3-RUBY [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-06-04.

Targeting Melanoma Hypoxia with the Food-Grade Lactic Acid Bacterium Lactococcus Lactis

Melanoma is the most aggressive form of skin cancer. Hypoxia is a feature of the tumor microenvironment that reduces efficacy of immuno- and chemotherapies, resulting in poor clinical outcomes. Lactococcus lactis is a facultative anaerobic gram-positive lactic acid bacterium (LAB) that is Generally Recognized as Safe (GRAS). Recently, the use of LAB as a delivery vehicle has emerged as an alternative strategy to deliver therapeutic molecules; therefore, we investigated whether L. lactis can target and localize within melanoma hypoxic niches. To simulate hypoxic conditions in vitro, melanoma cells A2058, A375 and MeWo were cultured in a chamber with a gas mixture of 5% CO₂, 94% N₂ and 1% O₂. Among the cell lines tested, MeWo cells displayed greater survival rates when compared to A2058 and A375 cells. Co-cultures of L. lactis expressing GFP or mCherry and MeWo cells revealed that L. lactis efficiently express the transgenes under hypoxic conditions. Moreover, multispectral optoacoustic tomography (MSOT), and near infrared (NIR) imaging of tumor-bearing BALB/c mice revealed that the intravenous injection of either L. lactis expressing β-galactosidase (β-gal) or infrared fluorescent protein (IRFP713) results in the establishment of the recombinant bacteria within tumor hypoxic niches. Overall, our data suggest that L. lactis represents an alternative strategy to target and deliver therapeutic molecules into the tumor hypoxic microenvironment.

Imaging Inflammation and Infection in the Gastrointestinal Tract

A variety of seemingly non-specific symptoms manifest within the gastrointestinal (GI) tract, particularly in the colon, in response to inflammation, infection, or a combination thereof. Differentiation between symptom sources can often be achieved using various radiologic studies. Although it is not possible to provide a comprehensive survey of imaging gastrointestinal GI tract infections in a single article, the purpose of this review is to survey several topics on imaging of GI tract inflammation and infections. The review discusses such modalities as computed tomography, positron emission tomography, ultrasound, endoscopy, and magnetic resonance imaging while looking at up-an-coming technologies that could improve diagnoses and patient comfort. The discussion is accomplished through examining a combination of organ-based and organism-based approaches, with accompanying selected case examples. Specific focus is placed on the bacterial infections caused by Shigella spp., Escherichia coli, Clostridium difficile, Salmonella, and inflammatory conditions of diverticulitis and irritable bowel disease. These infectious and inflammatory diseases and their detection via molecular imaging will be compared including the appropriate differential diagnostic considerations.

Publisher Correction: On the issue of transparency and reproducibility in nanomedicine

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Publisher Correction: On the issue of transparency and reproducibility in nanomedicine

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Abstract 1937: pH-responsive tumor-targeted mesoporous silica nanoparticle for the identification of pancreatic cancer using optoacoustic tomography

Purpose: Due to inadequate early detection and inability to operate at advanced stages, pancreatic ductal adenocarcinoma (PDAC) has remained one of the most difficult types of cancer to treat. A small range of non-specific symptoms coupled with quick metastasis rate result in a poor 5-year survival rate; 14% for those diagnosed within stage IA, and as low as 1% for those diagnosed during stage IV. Nanoparticles have recently emerged as a potential delivery agent for diagnostic and therapeutic agents, and although clinical success has not been ample due to targeting accuracy issues. This work shows a nanoparticle that has been functionalized with a pancreatic cancer-specific targeting ligand and exhibits specific particle release in pancreatic malignant environment (pH 6.6) as compared to non-malignant environments (pH 7.4). Methods: Wormhole-pored mesoporous silica nanoparticles were formed at 80°C using Tetrapropyl orthosilicate (TPOS) and a scaffold of hexadecyltrimethyl-ammonium bromide (CTAB). Acetic acid and ethanol were used in dialysis procedures to remove the CTAB scaffold and create worm-like pores. Chitosan was added to coat the silica particles and serve as a gatekeeper. IR-780 was added before the solution was acidified to load the dye into the worm-hole particles created. Shortly after, the solution pH was raised back to physiological levels (pH=7.4) to trap the dye within the particle. The particle surfaces were functionalized to attach a targeting ligand pH-low insertion peptide (V7) to conjugate the dye-loaded nanoparticles. Pancreatic adenocarcinoma cells (S2VP10 line) were plated in pH-7.4,6.8, and 6.6 PBS solutions with the loaded particles to assess uptake via near-infrared fluorescence and multispectral optoacoustic imaging. Results: Zeta potential and dynamic light scattering were used to ensure the 63nm size nanoparticle and proper coating. Near-infrared fluorescence imaging showed ~10X increased signal at pH 6.6 as compared to pH=7.4. MSOT imaging ~5X increased signal in the malignant microenvironment environment that is acidic as compared to the non-malignant environment at pH 7.4. Conclusion: The functionalized wormhole mesoporous silica nanoparticles coated with chitosan demonstrated pH-sensitivity in terms of cellular uptake via NIR fluorescence and MSOT imaging.

Citation Format: William MacCuaig, Abhilash Samykutty, Molly McNally, Kylie Nairon, Surya Banks, William Grizzle, Lacey R. McNally. pH-responsive tumor-targeted mesoporous silica nanoparticle for the identification of pancreatic cancer using optoacoustic tomography [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1937.

Abstract 1952: Tumor microenvironment targeted Rosella nanoparticle for the detection of triple negative breast cancer by multispectral optoacoustic tomography

Purpose: Recent advances in the nanotechnology and molecular imaging provides an excellent opportunity for development of delivery vehicles and imaging probes to improve real-time assessment and early detection of breast cancer progression.The absence of estrogen receptor (ER), progesterone receptor (PR), or HER-2 genes, represents a major clinical challenge for triple negative breast cancer (TNBC). Because of the absence of reliable markers, there is an unmet clinical need for developing efficient methods to identify TNBC. We have developed an acidic pH targeted Rosella nanoparticles that can actively release IR780 dye into orthotopically implanted TNBC tumors to improve tumor detection using multispectral optoacoustic imaging technology (MSOT).

Methods: The Rosella nanoparticles are a mesoporous silica base with wormhole pore architecture containing a chitosan gatekeeper and V3 pHLIP targeting peptide. The particles were synthesized using the sol-gel method and characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The Rosella particles were loaded with propidium Iodide (PI) or IR780 infrared imaging dye to evaluate pH-sensitive cargo release. Female athymic mice were implanted with MDA-MB-468 breast cancer cells by the mammary fat pad injection. Once the tumor reaches 3mm in size, athymic mice were intravenously injected with ROSELLA nanoparticles carrying IR780 dye and were imaged with MSOT.

Results: We have synthesized the Rosella nanoparticle with wormhole pores that is 27 nm diameter and can encapsulate the IR780 imaging probes for the detection of the TNBC. The Rosella particle contains a chitosan gatekeeper which can degrade upon contact with acidic pH tumor to prevent off-target release and is further sensitized to pH using V3 peptide. The Rosella nanoparticles can detect acidic tumor microenvironment and can penetrate inside the tumor cells. As a model of TNBC, we have injected MDA-MB-468 cells into the mammary fat pad of the female athymic mice to develop breast tumors. Once the tumor reached 3mm in size, we have intravenously delivered ROSELLA nanoparticles to the athymic mice with TNBC tumors. Our results were demonstrated that the intravenous injection of the ROSELLA particles could detect the orthotopically implanted TNBC tumors (p&lt;0.0001,n=5).

Conclusion: most aggressive subtypes of breast cancer, TNBC has a poor response for majority of the FDA-approved breast cancer drugs. To overcome these limitations, the distinct nanoformulations with potent imaging technology will enable to develop tumor-penetrating nanoparticles to more effectively deliver chemotherapeutics or imaging agents with least off-target effects. Future translation of these technologies has a high clinical impact concerning our current treatment options for TNBC patients.

Citation Format: Abhilash Samykutty, Molly McNally, Alexandra Thomas, William Grizzle, Lacey R. McNally. Tumor microenvironment targeted Rosella nanoparticle for the detection of triple negative breast cancer by multispectral optoacoustic tomography [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1952.

Abstract 1954: Tracking of orally-administered particles within the gastrointestinal tract of murine models using multispectral optoacoustic tomography

While particle carriers have potential to revolutionize disease treatment, using these carriers requires knowledge of spatial and temporal biodistribution. The goal of this study was to track orally administered particle uptake and trafficking through the murine gastrointestinal (GI) tract using multispectral optoacoustic tomography (MSOT).

Polylactic acid (PLA) particles encapsulating AlexaFluor 680 (AF680) dye conjugated to bovine serum albumin (BSA) were orally gavaged into mice. Particle uptake and trafficking were observed using MSOT imaging with subsequent confirmation of particle uptake via fluorescent microscopy. Mice treated with PLA-AF680-BSA particles exhibited MSOT signal within the small bowel wall at 1 and 6 h, colon wall at 6, 12, and 24 h, and mesenteric lymph node 24 and 48h. Particle localization identified using MSOT correlated with fluorescence microscopy. Despite the potential of GI tract motion artifacts, MSOT allowed for teal-time tracking of particles within the GI tract in a non-invasive and real-time manner.

Future use of MSOT in conjunction with particles containing both protein-conjugated fluorophores as well as therapeutic agents could allow for non-invasive, real time tracking of particle uptake and drug delivery.

Citation Format: Neal Bhutiani, Abhilash Samykutty, Kelly McMasters, Nejat Egilmez, Lacey R. McNally. Tracking of orally-administered particles within the gastrointestinal tract of murine models using multispectral optoacoustic tomography [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1954.

Abstract 1934: Development of spectrally distinct silica coated gold nanorods for detection of cancer using MSOT

Traditional cancer imaging devices are limited in their ability to screen for multiple contrast agents simultaneously in real time. Multispectral Optoacoustic Tomography (MSOT) is an emerging imaging modality capable of real-time imaging of numerous contrast agents with enhanced spatial resolution of 75µm at depths of 5 cm. The use of exogenous contrast agents in MSOT remains largely unexplored, so we developed two species of spectrally distinct gold nanorod as contrast agents for use in MSOT. Our goal was to evaluate the potential of MSOT to spectrally differentiate two exogenous contrast agents simultaneously. Two gold nanorod species were created using hydrogen peroxide (GNR-H2O2) or ascorbic (GNR-ASC) acid as reducing agents to modify the length of each species to create nanorods with individual light absorbance spectra in the IR range (680-900 nm). These gold nanorods were highly stabilized via encapsulation with mesoporous silica along with a subsequent chitosan capping. Human epidermal growth factor receptor 2 positive (HER2+) cells were specifically targeted by conjugating these mesoporous silica-coated chitosan capped gold nanorods (CMGs) to Trastuzumab resulting in TRA-CMG particles. Both TRA-CMG-ASC and TRA-CMG-H2O2 resulted in optoacoustic spectrally distinct signals when imaged in tissue phantoms both individually as well as mixed within the same well after multispectral processing using linear regression. Treatment of HER2+ breast cancer cell lines, DY36T2Q and SKBR3, with TRA-CMG-H2O2 resulted in 2.5x and 3.1x enhanced signal, respectively, as compared to HER2- MDA-MD468 cells. Treatment of DY36T2Q and SKBR3 cells with TRA-CMG-ASC demonstrated 3.7x and 6.9x, respectively, compared to MDA-MD468. In all three cell lines treated with a combination of TRA-CMG-H2O2’s and TRA-CMG-ASC’s clear and distinct signals were observed for each particle, demonstrating that each TRA-CMG possessed and maintained a detectibly distinct optoacoustic spectrum, in the IR range, allowing them to be detectable as separate contrast agents in MSOT while proximate to other targeted contrast agents. Both particles have demonstrated that they can be simultaneously administered and targeted at HER2+ cell while also maintaining distinct photoacoustic signals in MSOT upon consolidation. Each particle species, targeted to the same cells, were capable of being monitored individually in the presence of the other gold nanorod contrast agent.

Citation Format: Karl N. Thomas, Abhilash Samykutty, Molly McNally, Lacey R. McNally. Development of spectrally distinct silica coated gold nanorods for detection of cancer using MSOT [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1934.

Incidence and Survival Among Young Women With Stage I-III Breast Cancer: SEER 2000-2015

Background

Although recent findings suggest that de novo stage IV breast cancer is increasing in premenopausal women in the United States, contemporary incidence and survival data are lacking for stage I-III cancer.

Methods

Women aged 20-29 (n = 3826), 30-39 (n = 34 585), and 40-49 (n = 126 552) years who were diagnosed with stage I-III breast cancer from 2000 to 2015 were identified from the Surveillance, Epidemiology, and End Results 18 registries database. Age-adjusted, average annual percentage changes in incidence and 5- and 10-year Kaplan-Meier survival curves were estimated by race and ethnicity, stage, and hormone receptor (HR) status and grade (low to well and moderately differentiated; high to poorly and undifferentiated) for each age decade.

Results

The average annual percentage change in incidence was positive for each age decade and was highest among women aged 20-29 years. Increased incidence was driven largely by HR+ cancer, particularly HR+ low-grade cancer in women aged 20-29 and 40-49 years. By 2015, incidence of HR+ low- and high-grade cancer each independently exceeded incidence of HR- cancer in each age decade. Survival for HR+ low- and high-grade cancer decreased with decreasing age; survival for HR- cancer was similar across age decades. Among all women aged 20-29 years, 10-year survival for HR+ high-grade cancer was lower than that for HR+ low-grade or HR- cancer. Among women aged 20-29 years with stage I cancer, 10-year survival was lowest for HR+ high-grade cancer.

Conclusions

HR+ breast cancer is increasing in incidence among premenopausal women, and HR+ high-grade cancer was associated with reduced survival among women aged 20-29 years. Our findings can help guide further evaluation of preventive, diagnostic, and therapeutic strategies for breast cancer among premenopausal women.

In vivo tracking of orally-administered particles within the gastrointestinal tract of murine models using multispectral optoacoustic tomography

While particle carriers have potential to revolutionize disease treatment, using these carriers requires knowledge of spatial and temporal biodistribution. The goal of this study was to track orally administered particle uptake and trafficking through the murine gastrointestinal (GI) tract using multispectral optoacoustic tomography (MSOT). Polylactic acid (PLA) particles encapsulating AlexaFluor 680 (AF680) dye conjugated to bovine serum albumin (BSA) were orally gavaged into mice. Particle uptake and trafficking were observed using MSOT imaging with subsequent confirmation of particle uptake via fluorescent microscopy. Mice treated with PLA-AF680-BSA particles exhibited MSOT signal within the small bowel wall at 1 and 6 h, colon wall at 6, 12, and 24 h, and mesenteric lymph node 24 and 48 h. Particle localization identified using MSOT correlated with fluorescence microscopy. Despite the potential of GI tract motion artifacts, MSOT allowed for teal-time tracking of particles within the GI tract in a non-invasive and real-time manner. Future use of MSOT in conjunction with particles containing both protein-conjugated fluorophores as well as therapeutic agents could allow for non-invasive, real time tracking of particle uptake and drug delivery.

Abstract P1-08-03: An early look at incidence and survival by HR and HER2 status among young US women with stage I-III breast cancer: SEER 2010-15

Background: Population-based contemporary incidence and survival patterns for breast cancer by receptor status (hormone receptor [HR]; human epidermal growth factor receptor 2 [HER2]) among young US women have not been described.

Methods: We identified pre-, peri-, and early postmenopausal women ages 20-29 (n=1,617), 30-39 (n=12,910), 40-49 (n=47,313), and 50-59 (n=68,870) diagnosed with Stage I-III breast cancer from 2010-15 in the Surveillance, Epidemiology and End Results (SEER) database using SEER*Stat version 8.3.5. Of these, respective totals for women with reported HR and non-borderline HER2 status were 1533 (94.8%), 12,225 (94.6%), 44,684 (94.4%), and 64,844 (94.2%). Using this analytic sample, we estimated annual percentage change (APC) in incidence. Restricting the sample to women diagnosed from 2010-14, we estimated four-year survival (maximum available follow-up). Analyses were stratified by age group and receptor status.

Results: The proportion of HER2+/HR+ cancer was highest among women 20-29, decreasing with increasing age; that for HER2+/HR- cancer was lower, differing less across age groups (Table 1). For HER2- cancer, the proportion of HER2-/HR+ cancer was lowest for women 20-29 and increased with age; the opposite pattern was observed for HER2-/HR- cancer. Overall, stage I-III breast cancer increased in incidence from 2010-15 for all age groups, with the APC greatest in women 20-29 [2.20](30-39 [1.98], 40-49 [1.91], 50-59 [1.62]). The patterns for the APCs by age and receptor status tended to reflect those for the observed proportions, except those for women with HER2+/HR- cancer, which tended to increase with increasing age (Table 1). Four-year survival estimates for women 20-29, although imprecise, differed by HER2 status, being higher for those with HER2+ than HER2- cancer, and this difference persisted for HR+ and HR- cancers among these women (Table 2). In the other age groups, survival differed by HR status, being higher for women with HR+ than HR- cancer.

Conclusions: Using SEER data representative of over one-quarter of the US population, Stage I-III breast cancer has increased among young women in recent years. In particular, HER2+/HR+ and HER2-/HR- cancers were over-represented and estimated to have the highest APCs among women 20-39 compared to those 40-59. Receptor status was observed to influence survival differently across age groups. The differences in four-year survival observed among women 20-29 with HR+ cancers may have implications as we consider anti-estrogen therapy options for these youngest premenopausal women.

Table 1:Breast Cancer Frequency and APCReceptorsAge 20-2930-3940-4950-59 N (%)   HER2+/HR+331(21.6)2225(18.2)5865(13.1)7706(11.9)HER2+/HR-109(7.1)863(7.0)2254(5.0)3664(5.7)HER2-/HR+733(47.8)6769(55.2)30809(69.0)45693(70.5)HER2-/HR-360(23.5)2398(19.6)5756(12.9)7781(12.0) APCHER2+/HR+5.44.93.94.4HER2+/HR-1.22.14.43.2HER2-/HR+-1.11.51.91.6HER2-/HR-6.50.5-1.1-1.5

Table 2:Four-Year Breast Cancer SurvivalReceptorsAge 20-2930-3940-4950-59 %(SE)   HER2+/HR+95.3(1.7)95.5(0.6)96.0(0.4)94.4(0.4)HER2-/HR+95.0(2.9)91.9(1.3)90.8(0.9)90.8(0.7)HER2-/HR+90.6(1.6)93.1(0.4)96.2(0.2)95.6(0.1)HER2-/HR-82.2(2.8)80.3(1.1)82.8(0.7)82.5(0.6)SE: standard error

Citation Format: Thomas A, Rhoads A, Pinkerton E, Melin S, Oleson JJ, McNally LR, Hundley WG, Conway K, Lynch CF, Romitti PA. An early look at incidence and survival by HR and HER2 status among young US women with stage I-III breast cancer: SEER 2010-15 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-08-03.

Optoacoustic imaging identifies ovarian cancer using a microenvironment targeted theranostic wormhole mesoporous silica nanoparticle

At the intersection of the newly emerging fields of optoacoustic imaging and theranostic nanomedicine, promising clinical progress can be made in dismal prognosis of ovarian cancer. An acidic pH targeted wormhole mesoporous silica nanoparticle (V7-RUBY) was developed to serve as a novel tumor specific theranostic nanoparticle detectable using multispectral optoacoustic tomographic (MSOT) imaging. We report the synthesis of a small, < 40 nm, biocompatible asymmetric wormhole pore mesoporous silica core particle that has both large loading capacity and favorable release kinetics combined with tumor-specific targeting and gatekeeping. V7-RUBY exploits the acidic tumor microenvironment for tumor-specific targeting and tumor-specific release. In vitro, treatment with V7-RUBY containing either paclitaxel or carboplatin resulted in increased cell death at pH 6.6 in comparison to drug alone (p < 0.0001). In orthotopic ovarian xenograft mouse models, V7-RUBY containing IR780 was specifically detected within the tumor 7X and 4X higher than the liver and >10X higher than in the kidney using both multispectral optoacoustic tomography (MSOT) imaging with secondary confirmation using near infrared fluorescence imaging (p < 0.0004). The V7-RUBY system carrying a cargo of either contrast agent or an anti-neoplastic drug has the potential to become a theranostic nanoparticle which can improve both diagnosis and treatment of ovarian cancer.

Small Molecule Optoacoustic Contrast Agents: An Unexplored Avenue for Enhancing In Vivo Imaging

Almost every variety of medical imaging technique relies heavily on exogenous contrast agents to generate high-resolution images of biological structures. Organic small molecule contrast agents, in particular, are well suited for biomedical imaging applications due to their favorable biocompatibility and amenability to structural modification. PET/SPECT, MRI, and fluorescence imaging all have a large host of small molecule contrast agents developed for them, and there exists an academic understanding of how these compounds can be developed. Optoacoustic imaging is a relatively newer imaging technique and, as such, lacks well-established small molecule contrast agents; many of the contrast agents used are the same ones which have found use in fluorescence imaging applications. Many commonly-used fluorescent dyes have found successful application in optoacoustic imaging, but others generate no detectable signal. Moreover, the structural features that either enable a molecule to generate a detectable optoacoustic signal or prevent it from doing so are poorly understood, so design of new contrast agents lacks direction. This review aims to compile the small molecule optoacoustic contrast agents that have been successfully employed in the literature to bridge the information gap between molecular design and optoacoustic signal generation. The information contained within will help to provide direction for the future synthesis of optoacoustic contrast agents.

Osteopontin-targeted probe detects orthotopic breast cancers using optoacoustic imaging

Improved detection of breast cancer using highly sensitive, tumor-specific imaging would facilitate diagnosis, surveillance and assessment of response to treatment. We conjugated osteopontin peptide to an infrared fluorescent dye to serve as a contrast agent for detection of breast cancer by multispectral optoacoustic tomography (MSOT). Selective binding of the osteopontin-based probe was identified using flow cytometry and near infrared fluorescent imaging in triple negative and HER2 positive breast cancer cell lines in vitro. Osteopontin-750 accumulation was evaluated in vivo using MSOT with secondary confirmation of signal accumulation using near infrared fluorescent imaging. The osteopontin-based probe demonstrated binding to breast cancer cells in vitro. Similarly, after intravenous administration of the osteopontin-750 probe, it accumulated preferentially in the subcutaneous breast tumor in nude mice (557 MSOT a.u. compared to untargeted organs such as kidney (53.7 MSOT a.u.) and liver (32.1 MSOT a.u.). At 2.5 h post-injection, signal intensity within the tumor was 9.7 and 17 times greater in the tumor bed than in the kidney or liver, respectively. Fluorescence imaging ex vivo comparing tumor signal to that of nontarget organs confirmed the results in vivo. MSOT imaging demonstrated selective accumulation of the fluorescent osteopontin targeting probe to tumor sites both in vitro and in vivo, and provided high-resolution images. Further development of this tool is promising for advanced diagnostic imaging, disease surveillance and therapeutic models that limit nontarget toxicity.

Applying dynamic contrast enhanced MSOT imaging to intratumoral pharmacokinetic modeling

Examining the dynamics of an agent in the tumor microenvironment can offer critical insights to the influx rate and accumulation of the agent. Intratumoral kinetic characterization in the in vivo setting can further elicudate distribution patterns and tumor microenvironment. Dynamic contrast-enhanced Multispectral Optoacoustic Tomographic imaging (DCE-MSOT) acquires serial MSOT images with the administration of an exogenous contrast agent over time. We tracked the dynamics of a tumor-targeted contrast agent, HypoxiSense 680 (HS680), in breast xenograft mouse models using MSOT. Arterial input function (AIF) approach with MSOT imaging allowed for tracking HS680 dynamics within the mouse. The optoacoustic signal for HS680 was quantified using the ROI function in the ViewMSOT software. A two-compartment pharmacokinetics (PK) model constructed in MATLAB to fit rate parameters. The contrast influx (k_in) and outflux (k_out) rate constants predicted are k_in = 1.96 × 10^-2 s^-1 and k_out = 9.5 × 10^-3 s^-1 (R = 0.9945).

Abstract 4122: Acidic tumor microenvironment targeted wormhole-shaped mesoporous silica nanoparticles to detect ovarian cancer by multispectral optoacoustic tomography

Purpose: The implementation of the innovative technologies remains the top priority for the development of potential modalities for the diagnosis and treatment of various cancers. Despite all the recent advances, ovarian cancer is considered as a lethal gynecologic malignancy in which vast majority of the cases are diagnosed at the late metastatic stage at which the prognosis is poor. Because of the few apparent early symptoms, significant effort was made for developing efficient methods to identify early progression of the disease. We demonstrated that the bioconjugation of the V7 peptide on 27nm wormhole mesoporous silica nanoparticles (V7-CWMSN) particles specifically release the IR780 imaging probe at the orthotopically implanted early-stage ovarian tumor to detect by multispectral optoacoustic imaging technology (MSOT).

Methods: Wormhole mesoporous silica nanoparticles (WMSN) were synthesized by sol-gel chemistry. The WMSN were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The surface of the WMSN particle was functionalized with pH sensitizer chitosan to obtain CWMSN. The CWMSN particle was loaded with propidium Iodide (PI) or IR780 infrared imaging dye. Further, the conjugation of the CWMSN with V7 pHLIP peptide (V7-CWMSN) developed pH sensitive cargo release from the nanoparticles. Female athymic mice were orthotopically implanted with ES-2 ovarian cancer cells. Following 10 days of orthotopic implantation of the tumor cells, mice were intravenously injected with V7-CWMSN particles containing IR780 dye and were imaged with MSOT.

Results: In the current study, we have synthesized the wormhole-shaped mesoporous silica particles (WMSN) with the 27 nm diameter carrying IR780 imaging probes for the detection of early-stage ovarian cancer. The V7 peptide undergoes a conformational change upon contact with the acidic tumor microenvironment. Also, the chitosan crosslinking on the surface of the particles (V7-CWMSN) acts as a gatekeeper that is degradable upon contact with acidic pH tumor to prevent off-target release. As a model for ovarian cancer, we have used athymic mice orthotopically implanted with ovarian cancer cells. This model closely resembles the human ovarian cancer pathophysiology. Our results have demonstrated that the intravenous delivery of V7-CWMSN particles could detect the orthotopically implanted early-stage ovarian tumors (p&lt;0.0001,n=5).

Conclusion: The development of the distinct nanoformulations with potent imaging technology enables the visualization of early-stage ovarian tumors. Translating these modalities may allow clinicians to identify early-stage malignancies that are currently undetectable through conventional imaging techniques.

Citation Format: Abhilash Samykutty, Molly W. McNally, William E. Grizzle, Akiko Chiba, Alexandra Thomas, Lacey R. McNally. Acidic tumor microenvironment targeted wormhole-shaped mesoporous silica nanoparticles to detect ovarian cancer by multispectral optoacoustic tomography [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4122.

Abstract 4269: Dynamic contrast-enhanced MSOT imaging to intratumoral pharmacokinetic modeling

Introduction: Interactions between biological features and nanoparticles could affect tracer biodistribution, kinetics, clearance, and translocation. Because these effects cannot be simply extrapolated from in vitro studies, in vivo quantitative data are needed to determine the pharmacokinetic properties of tracers. Planar fluorescence or 2D fluorescent /bioluminescence imaging has the potential for the tracers to accumulate outside of the tumor and the potential of light scattering. MSOT allows for more precise determination of signal origin and intensity. HypoxiSense 680 is a tracer that targets the hypoxic tumor environment. Our objective is to assess the pharmacokinetics of HypoxiSense 680 in the context of an orthotopic breast tumor in vivo using MSOT. This study takes advantage of a novel contrast tracking imaging modality to study intratumoral pharmacokinetics in in vivo setting with a hypoxia-targeting tracer. Methods: Female, athymic mice were orthotopically implanted with MDA-MB-231 cells and tumors were allowed to grow to 4mm in diameter prior to the evaluation of the tracer. Mice were anesthetized with isoflurane and a mixture of 0.1L of O2 and 0.9L of medical air prior to the insertion of a tail vein catheter. The mouse was placed into the MSOT scanner for 10 minutes to equilibrate. Once the breast tumor was localized, images were acquired for 5 minutes to obtain a baseline measurement. Subsequently, 100μL of HypoxiSense 680 at the recommended dosage of 2nmol per mouse was injected over the course of 30s followed by a catheter flush with 100μL of saline solution. MSOT inVision 256-TF continuously measured optoacoustic signal within the mouse in vivo for a duration of 25 minutes. HypoxiSense 680 signal was isolated by spectral unmixing using backprojection algorithm. Results: A 2-compartmental PK model was constructed in MATLAB and curve-fitted against the animal data. There were two compartments to account for the contrast within the circulatory system and the tumor microenvironment. Rate constants of the model were determined by fitting the model curve to the experimental MSOT imaging data: kforward=2.76x10-4 sec-1, kreverse=4.73x10-4 sec-1, kelcentral=1.01x10-5 sec-1, kelperipheral=3.18x10-7 sec-1. The goodness of fit was evaluated (R=0.83, RMSE=0.0015). Conclusion: Optoacoustic imaging with MSOT provides live tracking of spectrally unique contrasts in vivo. This capability allows for a novel characterization method of intratumoral drug/contrast kinetics in vivo in mouse tumor models.

Citation Format: Ted G. Xiao, Abhilash Samykutty, Jared Weis, Scott Gayzik, Umit Topaloglu, Alexandra Thomas, Akiko Chiba, Lacey R. McNally. Dynamic contrast-enhanced MSOT imaging to intratumoral pharmacokinetic modeling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4269.

Abstract 4664: Enzymatically-responsive tumor-targeted mesoporous silica nanoparticle for identification of pancreatic cancer

Purpose: Pancreatic cancer remains an unsolved health issue, with its rapid progression and resistance to modern therapy leading to poor prognoses for most patients. The prevalence of metastasis in pancreatic cancer makes complete tumor location and removal rare, and those who do have resectable disease have only a 20% 5-year survival rate. In recent years, nanoparticles have been explored as targeted delivery agents for chemotherapeutic drugs and imaging dyes, however few have achieved clinical success due to overestimation of biological phenomena and reliance on passive targeting systems. In this work, an enzyme-responsive nanoparticle has been developed for increased active pancreatic tumor targeting and specific release at biologically-significant enzyme concentrations.

Methods: Mesoporous silica nanoparticles were formed using a scaffold of hexadecyltrimethylammonium bromide (CTAB) at 80°C. The scaffold was removed to form wormhole-like pores using a series of dialysis procedures. Transmission electron microscopy (TEM) confirmed the 35 nm diameter and porous structure of the particles. The particles were then loaded with IR780 dye, and surfaces were functionalized with (3-aminopropyl) triethoxysilane (APTES). The loaded particles were then encapsulated with a combination of Type A and Type B gelatin, followed by a stabilizing polyvinylpyrrolidone (PVP) layer. Dynamic light scattering (DLS) and zeta potential were used to confirm coating. Coated particle samples were exposed to collagenase type IV (MMP-9) enzyme to test encapsulation efficiency and enzyme sensitivity. Enzyme-treated and intact samples were transferred to tissue phantoms, and Multispectral optoacoustic tomography (MSOT) was used for comparative analysis.

Results: TEM confirmed the formation of stable 35 nm silica nanoparticles with a wormhole-like pore structure. Zeta potential decrease from 55 mV to 5 mV and DLS particle diameter increase from 35 nm to 334.5 nm indicated binding of gelatin and PVP to particle surfaces. MSOT imaging showed 10 X increased signals from untreated nanoparticles as compared to enzyme-treated nanoparticles, indicating that dye molecules remained inside the pores of coated particles and were released when exposed to MMP-9.

Conclusion: Gelatin/PVP-coated mesoporous silica nanoparticles encapsulated dye and demonstrated MMP-9 activated dye release at biologically-relevant enzyme concentrations.

Citation Format: Kylie Nairon, Abhilash Samykutty, Molly W. McNally, Girish Mishra, William E. Grizzle, Lacey R. McNally. Enzymatically-responsive tumor-targeted mesoporous silica nanoparticle for identification of pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4664.