Circulating tumor cells reveal early predictors of disease progression in patients with stage III NSCLC undergoing chemoradiation and immunotherapy

Circulating tumor cells (CTCs) are early signs of metastasis and can be used to monitor disease progression well before radiological detection by imaging. Using an ultrasensitive graphene oxide microfluidic chip nanotechnology built with graphene oxide sheets, we were able to demonstrate that CTCs can be specifically isolated and molecularly characterized to predict future progression in patients with stage III non-small cell lung cancer (NSCLC). We analyzed CTCs from 26 patients at six time points throughout the treatment course of chemoradiation followed by immune checkpoint inhibitor immunotherapy. We observed that CTCs decreased significantly during treatment, where a larger decrease in CTCs predicted a significantly longer progression-free survival time. Durvalumab-treated patients who have future progression were observed to have sustained higher programmed death ligand 1+ CTCs compared to stable patients. Gene expression profiling revealed phenotypically aggressive CTCs during chemoradiation. By using emerging innovative bioengineering approaches, we successfully show that CTCs are potential biomarkers to monitor and predict patient outcomes in patients with stage III NSCLC.

Abstract 2131: Immunoaffinity isolation of EpCAM expressing exosomes utilizing high throughput microfluidic chip with IEDDA chemistry (EpCAM-TCOOncoBean Chip)

The overall objective of this study is to investigate the microfluidic isolation of tumor derived exosome (TDEs) using the OncoBean Chip, functionalized with the unique inverse electron demand Diels-Alder (IEDDA) for downstream analysis of patient TDEs for therapeutic applications. This chemistry allows for capture and subsequent release of exosomes for immunomodulation and functional studies. We developed an approach for targeting TDEs in patient’s blood plasma by using the epithelial cell adhesion molecule (EpCAM) antibody, a highly expressed biomarker associated with non-small cell lung cancer.The OncoBean Chip is a high throughput radial-flow microfluidic device designed for the specific isolation of TDEs. The bean shaped micro-nodes allow for a varying shear profile to better capture nanosized particles by positioning them towards the middle curvature. We optimized the device using exosomes extracted from cell culture media by ultracentrifugation. First, the surface of the device was salinized with (3-Aminopropyl) triethoxysilane, as an anchor, following plasma activation of the surface. Then, bonded with 3,3'-dithiobis(sulfosuccinimidyl propionate) as a crosslinker, to facilitate the release. Finally, trans-cyclooctene (TCO) is attached as the exposed agent for capture of TDEs. The exosome sample is functionalized with an EpCAM antibody (Ab) conjugated to a tetrazine (Tz) molecule via incubation. The anti-EpCAM-Tz conjugate bonds to surface EpCAM on the TDEs creating a TDE-EpCAM-Tz complex for isolation. The TDEs are processed through the functionalized OncoBean Chip for Ab specific isolation. We tested and validated the EpCAM specific isolation and confirmed TDEs were forming complexes with the Ab-Tz conjugates and not arbitrarily sticking to the nodes. This was done by flowing a sample of TDE-Tz through a functionalized device where little to no capture was expected. Then we evaluated the isolation of EpCAM specific TDEs by using H1650 and A549 exosomes and comparing the capture with CD63, a common exosome marker. Limited capture is expected in the A549 group due to low EpCAM expression for the Ab-Tz conjugate to bind too.Additionally, EV isolation was confirmed and quantified by NTA which reveals capture efficiency up to 90% for the H1650 TDEs. Capture efficiency of the no Ab control was found to be at 30% and below while the A549 control, was found to be at about 20% and below. Hence, our OncoBean Chip with IEDDA chemistry has successfully demonstrated efficient and specific isolation of EpCAM and CD63 expressing TDEs from two different cell lines. Data from Western Blot analysis and scanning electron microscopy further confirm the physical characteristics and protein expression of the TDEs established by the International Society of Extracellular Vesicles (ISEV).

Citation Format: Nna-Emeka Onukwugha, Sunitha Nagrath, Henry McEacheron. Immunoaffinity isolation of EpCAM expressing exosomes utilizing high throughput microfluidic chip with IEDDA chemistry (EpCAM-TCOOncoBean Chip) [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 2131.

Emerging micro-nanotechnologies for extracellular vesicles in immuno-oncology: from target specific isolations to immunomodulation

Extracellular vesicles (EVs) have been hypothesized to incorporate a variety of crucial roles ranging from intercellular communication to tumor pathogenesis to cancer immunotherapy capabilities. Traditional EV isolation and characterization techniques cannot accurately and with specificity isolate subgroups of EVs, such as tumor-derived extracellular vesicles (TEVs) and immune-cell derived EVs, and are plagued with burdensome steps. To address these pivotal issues, multiplex microfluidic EV isolation/characterization and on-chip EV engineering may be imperative towards developing the next-generation EV-based immunotherapeutics. Henceforth, our aim is to expound the state of the art in EV isolation/characterization techniques and their limitations. Additionally, we seek to elucidate current work on total analytical system based technologies for simultaneous isolation and characterization and to summarize the immunogenic capabilities of EV subgroups, both innate and adaptive. In this review, we discuss recent state-of-art microfluidic/micro-nanotechnology based EV screening methods and EV engineering methods towards therapeutic use of EVs in immune-oncology. By venturing in this field of EV screening and immunotherapies, it is envisioned that transition into clinical settings can become less convoluted for clinicians.

Abstract 2792: On-chip evaluation of cancer cell-extracellular vesicle interactions using a novel microfluidic microsystem (CellExoChip)

Introduction: Analytical methods of extracellular vesicles (EVs) is becoming an increasingly promising field of study due to them being an effective biomarker for cancers. EVs are present in various types of body fluids, which can be easily used for diagnostic purpose. Prior research has explored numerous techniques for isolating and analyzing these EVs based on their physical and biochemical properties, however, the complexity of biological samples makes conventional EV isolation difficult to exclusively extract EVs of a certain type of cell. Current downstream analysis methods lack the ability to differentiate exosomes of different origins in a sample. Recent studies suggested the presence of certain proteins in cancer exosomes that facilitates preferential uptake of the exosomes by organ-specific cancer cells, called organotropism. Using this unique property, we devised a microfluidic platform to examine the uptake of specific exosomes onto their respective progenitor cell lines, thus aiming to use the interaction for cancer diagnosis purposes.

Methods: The CellExoChip was prepared following the standard PDMS-based soft lithography method. The device consists of an inlet and outlet, with dimensions of 22x22 mm with a cell capture area of about 50 mm2. The microfluidic device was functionalized by Streptavidin and the cancer cells were biotinylated with EZ-Link-NHS-Biotin to create an intense affinity between the cells and the device. We further injected dyed exosomes with different origins through the device and evaluated their specific uptake using fluorescence microscope.

Results: The prepared CellExoChip successfully immobilized over 1,500 cells onto the surface and viability evaluation demonstrated that only 6.79% of the initial cells were sacrificed during the biotinylation and on-chip binding process. The average on-chip cell viability showed 75.47±7.68%. The uptake of lung cancer cell exosomes into three different cancer cell lines (lung, bladder and breast) was measured on chip. The relative uptake of lung cell exosomes by the respective lung cells was 100% compared to the bladder cells and breast cell which were 15.87% and 40.31%, respectively. We extended this specific uptake evaluation to other LungCell-LungExo combinations using H1650, A549, and in-house CTC cell line, CTCR5, and the results demonstrated the organotropism nature of the exosomes in lung cancer.

Discussion and conclusion: We present a novel screening method to accurately characterize specific cancer-derived EVs using a microfluidic platform. This process bypasses the requirement of analyzing and profiling these embedded proteins prior to EV isolation. Our microfluidic device facilitates this interaction between cells and exosomes through the diagnosis process of liquid biopsy.

Citation Format: Kruthi Srinivasa Raju, Zeqi Niu, Joseph Marvar, Shawn Fortna, Nna-Emeka Onukwugha, Yoon-Tae Kang, Sunitha Nagrath. On-chip evaluation of cancer cell-extracellular vesicle interactions using a novel microfluidic microsystem (CellExoChip) [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 2792.

Electrochemical Strategy for Eradicating Fluconazole-Tolerant Candida albicans Using Implantable Titanium

A persistent problem in modern health care derives from the overwhelming presence of antibiotic-resistant microbes on biomaterials, more specifically, fungal growth on metal-based implants. This study seeks to investigate the antifungal properties of low-level electrochemical treatments delivered using titanium electrodes against Candida albicans. We show that C. albicans can be readily controlled with electrical currents/potentials, reducing the number of viable planktonic cells by 99.7% and biofilm cells by 96.0-99.99%. Additionally, this study explores the ability of the electrochemical treatments to potentiate fluconazole, a clinically used antifungal drug. We have found that electrochemical treatment substantially enhances fluconazole killing activity. While fluconazole alone exhibits a low efficiency against the stationary phase and biofilm cells of C. albicans, complete eradication corresponding to 7-log killing is achieved when the antifungal drug is provided subsequently to the electrochemical treatment. Further mechanistic analyses have revealed that the sequential treatment shows a complex multimodal action, including the disruption of cell wall integrity and permeability, impaired metabolic functions, and enhanced susceptibility to fluconazole, while altering the biofilm structure. Altogether, we have developed and optimized a new therapeutic strategy to sensitize and facilitate the eradication of fluconazole-tolerant microbes from implantable materials. This work is expected to help advance the use of electrochemical approaches in the treatment of infections caused by C. albicans in both nosocomial and clinical cases.