Liquid Biopsies

Question 1

What is a liquid biopsy?

Answer 1

Sampling and analysis of non-solid biological tissue

Question 2

What does amniotic analysis test for?

Answer 2

Paternity
Sex
Chromosomal abnormalities

Question 3

Why is blood really good as a liquid biopsy?

Answer 3

Fragments from apoptotic cells make their way into the blood on their way to being discarded

Question 4

What can blood liquid biopsies test for?

Answer 4

Circulating endothelial cells
Circulating tumour cells
Disseminated tumor cells
Tumor educated platelets
Cell free nucleotides
Metabolites
Extracellular microvesicles

Question 5

What type of information can you get from a liquid biopsy?

Answer 5

Germline (hereditary) and somatic information

Question 6

How do you extract a liquid biopsy?

Answer 6

By taking 10mL blood by vernipuncture (4-5mL plasma)

Question 7

What do the biopsy tubes need to prevent?

Answer 7

Blood clots
Genomic DNA release
Haemolysis

Question 8

What do the EDTA and citrate tubes contain?

Answer 8

Anticoagulant to prevent clotting

Question 9

What are the properties of cell-free DNA tubes?

Answer 9

Contain a stabiliser to prevent release of gDNA from white blood and haemolysis of red blood cells

Question 10

What are circulating tumour cells?

Answer 10

Cells that have detached from a tumour and travelled through the bloodstream to other parts of the body

Question 11

How often do you find circulating tumour cells?

Answer 11

Rarely

1-10 in 1mL of blood

Question 12

How can you isolate circulating tumour cells?

Answer 12

Antibodies of cell surface markers

Size (they’re a little bit bigger than other cells)

Question 13

What can you use to analyse circulating tumour cells?

Answer 13

NGS, FISH, flow cytometry RTqPCR or in vivo/in vitro culture

Question 14

What does circulating tumour cell analysis give information about?

Answer 14

The tumour they’ve detached from

Question 15

What concentration is circulating tumour DNA present in?

Answer 15

1-50ng DNA/mL plasma

Question 16

What does circulating tumour DNA provide information of?

Answer 16

Current genetic makeup

80-95% specificity and 60-85% sensitivity

Question 17

How do you isolate the circulating DNA?

Answer 17

Transfer the supernatant to a clean polypropylene tube and freeze it
Then isolate using magnetic beads cellulose or silica based systems

Question 18

What are the advantages of a liquid biopsy?

Answer 18

Low invasiveness
Higher patient compliance
Higher cost/effectiveness
Allow repeated access and multiple sampling
No special training needed for extraction

Question 19

What are the disadvantages of liquid biopsy?

Answer 19

Low amount of material
Early diagnosis
Data interpretation

Question 20

Why are liquid biopsies good for cancer biomarkers?

Answer 20

Molecular properties within a tumour differ so you get a better overview
No need to identify the tumor site before taking a biopsy
Allows for repeat sampling

Question 21

When can liquid biopsies be used in cancer biomarkers?

Answer 21

Early disease stages
Check disease response
Determine subsequent therapy

Question 22

What is an example of a currently approved cancer biomarker test?

Answer 22

EGFR mutation in lung cancer