“Isolation of rare circulating tumour cells in cancerpatients by microchip

technology”

Nagrath et al.Nature 2007

Peter Bojo

Big Picture

• Potential uses of CTCs– Choice of therapy– Monitoring of therapy– Explaining the biology of metastasis

• Microchip is one of many CTC technologies– Immunomagnetic beads– Total RNA qPCR

Microchip Design

• Blood pumped through forest of posts• ~80,000 posts on a ~10cmX10cm chip• EpCAM antibodies on posts• Testing with cancer cell spiked solutions

determines:– Flow rate ~1mL/hr– High capture efficiency even for low EpCAM

expression levels ~60%– Identical capture efficiency for whole blood and lysed

blood

Microchip Workflow1. Take whole blood sample,flow through optimized chip

2. Stain with DAPI, cytokeratin, and CD45 antibodies. 47% purity

3. Analyze CTC sensitivity, viability,and predictive ability

Cancer Patient CTC Experiment

• NSCLC, prostate, pancreatic, breast, and colon cancer samples.

• Metastatic and non-metastatic prostate cancer samples.

• Isolated between 5 and 1300 CTCs per patient in 115/116 cases.

• 0 CTCs in healthy samples

• High sensitivity

Predictive Ability for Cancer Treatment

Conclusions

• Microchip is a competitive CTC enrichment technology

• Uses unprocessed blood• High purity of isolated cells: 47% • High sensitivity: 99%• Capture efficiency: ~60%• High cell viability: 98%• Further Study warranted for:

– CTC count and tumor size correlation– Comparable numbers of CTCs in localized and

metastatic cancers