Liquid Biopsy Based on Circulating Cancer-Associated Cells: Bridging the Gap from an Emerging Concept to a Mainstream Tool in Precision Medicine

A protocol to clinically evaluate liquid biopsies as a tool to speed up diagnosis of children and young adults with aggressive infection-related lymphoma in East Africa "(AI-REAL)"

Background

The capacity for invasive tissue biopsies followed by histopathology diagnosis in sub-Saharan Africa is severely limited. Consequently, many cancer patients are diagnosed late and outcomes are poor. Here, we propose to evaluate circulating tumour (ct) DNA analysis (“liquid biopsy”), a less invasive and faster approach to diagnose endemic EBV-driven lymphomas (EBVL) in East Africa.

Methods

We will evaluate the clinical utility of an already validated ctDNA test prospectively in a head-to-head comparison against histopathology. The primary endpoint is the time from presentation to the specialist centre to a final diagnosis of EBV- Lymphoma. Secondary endpoints include the sensitivity and specificity of liquid biopsy and health economic benefits over histopathology. One hundred forty-six patients will be recruited over 18 months. Patients will be eligible if they are 3–30 years of age and have provided written consent or assent as per IRB guidelines. Tissue and venous blood samples will be processed as per established protocols. Clinical data will be captured securely and in real-time into a REDCap database. The time from presentation to diagnosis will be documented. The sensitivity and specificity of the methods can be estimated within 5% error margin with 95% confidence level using 73 cases and 73 controls. Health-economic assessment will include micro-costing of ctDNA test and histopathology. All results will be reviewed in a multidisciplinary tumour board.

Discussion

The study evaluates the clinical utility of ctDNA in improving the speed of diagnostic pathways for EBVL in sub-Saharan Africa. Our results would provide proof-of-principle that ctDNA can be used as a diagnostic tool in areas without access to regular pathology, that transfer of the tool is feasible, and that it leads to an earlier and faster diagnosis. The potential clinical and economic impact of this proposal is thus significant. If successful, this study will provide appropriate, and cost-effective diagnostic tools that will promote earlier diagnosis of EBVL and potentially other cancers in countries with restricted healthcare resources.

Trial registration

Pan African Clinical Trials Registry: PACTR202204822312651, registered on 14th-April-2022.

Single-Cell Digital Microfluidic Mass Spectrometry Platform for Efficient and Multiplex Genotyping of Circulating Tumor Cells

Gene mutation profiling of heterogeneous circulating tumor cells (CTCs) offers comprehensive and real-time molecular information of tumors for targeted therapy guidance, but the lack of efficient and multiplex genotyping techniques for single-CTC analysis greatly hinders its development and clinical application. This paper reports a single-CTC mass spectrometry analysis method for efficient and multiplex mutation profiling based on digital microfluidics. Digital microfluidics affords integrated single-CTC manipulation, from single-CTC isolation to high-performance whole genome amplification, via nanoliter droplet-based wettability trapping and hydrodynamic adjustment of cell distribution. Coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, multiplex mutation information of individual CTCs can be efficiently and accurately identified by the inherent mass differences of different DNA sequences. This platform achieves Kirsten rat sarcoma viral oncogene mutation profiling of heterogeneous CTCs at the single-cell level from cancer patient samples, offering new avenues for genotype profiling of single CTCs and cancer therapy guidance.

The influence of cell elastic modulus on inertial positions in Poiseuille microflows

Microchannels are used as a transportation highway for suspended cells both in vivo and ex vivo. Lymphatic and cardiovascular systems transfer suspended cells through microchannels within the body, and microfluidic techniques such as lab-on-a-chip devices, flow cytometry, and CAR T-cell therapy utilize microchannels of similar sizes to analyze or separate suspended cells ex vivo. Understanding the forces that cells are subject to while traveling through these channels are important because certain applications exploit these cell properties for cell separation. This study investigated the influence that cytoskeletal impairment has on the inertial positions of circulating cells in laminar pipe flow. Two representative cancer cell lines were treated using cytochalasin D, and their inertial positions were investigated using particle streak imaging and compared between benign and metastatic cell lines. This resulted in a shift in inertial positions between benign and metastatic as well as treated and untreated cells. To determine and quantify the physical changes in the cells that resulted in this migration, staining and nanoindentation techniques were then used to determine the cells' size, circularity, and elastic modulus. It was found that the cells' exposure to cytochalasin D resulted in decreased elastic moduli of cells, with benign and metastatic cells showing decreases of 135 ± 91 and 130 ± 60 Pa, respectively, with no change in either size or shape. This caused benign, stiffer cancer cells to be more evenly distributed across the channel width than metastatic, deformable cancer cells; additionally, a decrease in the elastic moduli of both cell lines resulted in increased migration toward the channel center. These results indicate that the elastic modulus may play more of a part in the inertial migration of such cells than previously thought.