Opportunity
The incidence and mortality of malignant tumors are increasing, and traditional tumor screening and diagnostic methods, such as tissue biopsy, face significant limitations including limited detection efficacy and sampling difficulty, making it challenging to monitor tumor progression efficiently and flexibly. Circulating tumor cells (CTCs), which are cancer cells shed from solid tumors into the bloodstream, serve as crucial biomarkers for cancer diagnosis, treatment guidance, monitoring, and prognosis. However, CTCs are present in extremely low quantities in blood and exhibit heterogeneity. Furthermore, blood contains millions of white blood cells and billions of red blood cells, posing immense challenges for the isolation and analysis of CTCs. Existing isolation methods, such as those based on physical properties (e.g., density gradient centrifugation, membrane filtration) or affinity differences (e.g., immunomagnetic separation), have drawbacks. Physical methods often suffer from poor specificity and high background contamination from blood cells, while size-based methods fail to effectively enrich smaller CTCs. Therefore, there is a pressing need for an efficient, reliable, and highly specific method to enrich CTCs for accurate downstream analysis.
Technology
This patent presents an innovative method that combines immuno-affinity and size-based physical separation to overcome the limitations of existing CTC enrichment techniques. The core technology involves incubating a biological sample (e.g., blood) with immuno-microparticles. These microparticles, with an average diameter of 0.5μm to 10μm, are conjugated with one or more first antibodies (e.g., against EpCAM, N-cadherin, vimentin) that specifically bind to markers on the surface of CTCs. This incubation forms cell and microparticle aggregates (CPAs), where CTCs are bound to multiple microparticles. This binding significantly increases the effective size of the CTCs, with CPAs typically reaching 11μm to 35μm in average size. Subsequently, a size-based isolation method is employed to separate these enlarged CPAs from the much smaller background blood cells (typically 6-9μm). The size-based isolation can utilize a film microfilter with a pore size of 6-10μm or a microfluidic device, such as an inertial focusing chip. The inertial focusing chip leverages fluid dynamics to separate particles based on size; the enlarged CPAs follow a different flow path from smaller blood cells and are collected separately. This hybrid approach ensures high-specificity capture via antibody binding and highly efficient physical separation based on the amplified size difference, effectively enriching even small-sized CTCs that would otherwise be lost.
Advantages
- Significantly enhances CTC enrichment efficiency, with capture rates exceeding 90% for small cancer cells.
- Dramatically improves purity by removing over 99.9% of white blood cells, reducing background interference.
- Effectively enriches small-size CTCs that are missed by conventional size-based methods alone.
- The method is versatile and can target both epithelial and mesenchymal CTC markers, addressing tumor heterogeneity.
- Compatible with various downstream analytical techniques, including immunochemical, genomic, and transcriptomic analyses.
- The kit format standardizes the process, offering simplified operation and potential for clinical application.
- The inertial focusing microfluidic chip enables rapid, label-free, and continuous flow processing.
Applications
- Early cancer screening and non-invasive liquid biopsy.
- Auxiliary diagnosis and stratification of cancer patients.
- Real-time monitoring of treatment efficacy and cancer progression.
- Guidance for personalized therapy and drug selection.
- Prognostic assessment and detection of minimal residual disease.
- Cancer research, including studies on metastasis and tumor biology.
- Potential use with various sample types beyond blood, such as pleural effusion or ascites.
