BioMarker

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BioMarker
Definition
Biomarker is a substance used as an indicator of
a biologic state Existence of living
organisms or biological process. A particular
disease state A fragment of DNA sequence
Proteins
Nucleic acids
Carbohydrate
Lipids
Small molecules
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Biomarkers
Location of the biomarker
Location of a particular molecule can also be a
marker
Cellular-subcellular locations
Tissue or organ locations
Thymidylate synthase (TS)
nucleus vs the cytoplasm
The higher the level in NE, lower level in the
cyto. Lower survival in colorectal cancer
patients
Galectin-3
Galectin-3 is a member of lectin family. It is
wildly distributed In tissue of epithelial,
fibroblast, and dendritic cells.
Blood Galectin-3 Predict the outcomes
for patients with symptoms of heart failure
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Biomarker
Detection of biomarker
Detection of biomarker diagnosis Self
properties, e.g enzymatic activities Antibodies,
IHC, ELISA
Detection of biomarker Quantitative a link
between quantity of the marker and disease
Qualitative a link between exist of a
marker and disease
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Biomarker Diagnosis
Ideal Marker for diagnosis
Should have great sensitivity, specificity, and
accuracy in reflecting total disease burden. A
tumor marker should also be prognostic of outcome
and predictive of tumor recurrence and
effectiveness of anti-cancer treatments.
Biomarker for Screening

• The marker must be highly specific, minimize
  false positive and negative

• The marker must be able to clearly reflect the
  early stage of disease

• The marker must be easily detected without
  complicated medical
• procedures. The disease markers released to
  serum and urine are good
• targets for application of early screening.

• The method for screening should be cost
  effective.

Samples for biomarker detection
Blood, urine, or other body fluids samples
Tissue samples
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Biomarker Discovery and Validation
Correlation a biomarker vs a disease or status
of a disease Do not need understand functions
Detection Detection of a particular marker is
important
Validation Build statistical correlation large
number of samples
Validation sensitivity and specificity
Validation Stand alone vs along with other
markers
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Common Serum Markers for Cancer
Diagnosis/prognosis
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Common Biomarker for Cancer
AFP (gt100 ng/ml) Alpha fetoprotein (AFP) is
typically found in the developing fetus. Because
of the association of the rapid cell growth, this
fetal protein is also used as a tumor marker. non
cancerous liver diseases such as cirrhosis and
viral hepatitis can lead to high level AFP
CEA (gt10 ng/ml) Carcinoembryonic antigen (CEA) is
produced during fetal development. After birth,
the production of CEA stops and is undetectable.
CEA has also been found elevated in nonmalignant
tumors such as pleural effusions. Elevation of
CEA after conventional treatment of neoplasms has
been correlated with a recurrence of cancer
CA19-9 (gt37 U/ml) Carbohydrate Antigen 19-9 (CA
19-9) is present in the fetus in the epithelium
of the fetal stomach. It is primarily used as a
marker for pancreatic cancer. High levels also
exist in conditions such as non-malignant liver
disease and other disorders of the
gastrointestinal tract.
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Common Biomarker for Cancer
hTG (gt10 ng/ml ) Thyroglobulin (hTG) is a
glycoprotein that is found in thyroid gland. This
protein binds to thyroxine, which controls the
rate of metabolic processes in body.
HCG (gt10 mIU/ml ) Human Chorionic
Gonadotropin-beta (HCG) is normally produced by
the placenta during pregnancy, an indicator of
pregnancy. The protein can be detected in serum
or urine. Non-malignant elevations may be
observed in pregnancy, ulcers, dukes disease,
and cirrhosis. Levels of HCG are useful in
monitoring the effectiveness of treatment.
Ferr (gt120 ng/ml ) Ferritin is an iron binding
storage found in the liver, spleen, and bone
marrow. Elevated levels observed in non-cancerous
conditions include rheumatoid arthritis and
anemia
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Common Biomarker for Cancer
NSE (gt12 ng/ml ) Neuron Specific Enolase (NSE) is
produced by neurons and neuroendocrine cells of
the central and peripheral nervous system.
b2M (high level) Beta 2-Microglobulin, (B2M), is
an 11 kD protein associated with the outer
membrane of many cells including lymphocytes. It
is the small subunit of the MHC class I molecule.
B2M is present in small amounts in serum, csf,
and urine of normal people. A non-malignant
condition associated with high b2M levels is
pancreatitis
a2M (lt500 mg/ml ) Alpha 2 Macroglobulin (A2M) is
a large protease inhibitor, 720 kD, capable of
irreversibly binding and inhibiting a wide
variety of proteases including plasmin, pepsin,
trypsin, chymotrypsin, and cathepsin D.
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Prostate Cancer marker PSA
PSA is a protein normally made in the prostate
gland in ductal cells that make some of the
semen. PSA helps to keep the semen liquid. PSA,
also known as kallikrein III, seminin,
semenogelase, ?-seminoprotein and P-30 antigen,
is a glycoprotein, a serine protease
PSA has several forms in serum Free Pre-enzyme
Complex Inactive
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Prostate Cancer Diagnosis with PSA
Cancer of the prostate does not cause any
symptoms until it is locally advanced or
metastatic.
There is a correlation between elevated PSA and
prostate cancer.
Diagnosis of PSA for prostate cancer in the most
time means measure the PSA In serum samples.
Detection of PSA allow early detection of
prostate cancer.
Large screening trials have shown that PSA nearly
doubles the rate of detection possible by combine
with other methods. Based on these data, PSA
testing was approved by the US FDA for the
screening and early detection of prostate cancer.
PSA is also found in the cytoplasm of benign
prostate cells.
Separately measure different forms of PSA give
better results
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Prostate Marker PSMA
Prostate-specific membrane antigen (PSMA) is a
type 2 integral membrane glycoprotein. PSMA
possesses glutamate carboxypeptidase activity,
Detectable levels of PSMA are also found in small
intestine and brain. Intestinal PSMA may play a
role in the metabolism of dietary-glutamated
folate derivatives. Brain PSMA, also referred to
N-acetylated -linked acidic dipeptidase
(NAALADase), may modulate glutamatergic
neurotransmission
In addition to being abundantly and
preferentially expressed on the surface of
prostate cancer cells, PSMA is also present on
endothelial cells of new blood vessels
PSMA also expressed in brush border of proximal
tubules of normal kidneys and tissue samples from
both benign and malignant renal lesions
(neovasculature)
The role of PSMA as a cancer marker is still
under investigation. PSMA is sensitive to reflect
prostate cancer. The specificity, however, is not
fully verified. Most use is image the prostate
metastasis by radio-isotopes
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Prostate Marker PSMA
The role of enzymatic activity (folate hydrolase)
of PSMA in cellular transformation and metastasis
is not understood.
PSMA has isoforms produced by alternative
splicing. In normal prostate epithelia, PSMA is
expressed primarily as a cytoplasmic protein
termed PSM' In prostate carcinomas, however,
differential mRNA splicing leads to expression of
PSMA as a type 2 integral membrane glycoprotein
possessing a 19-aa cytoplasmic fragment, a single
24-aa membrane-spanning domain, and a 707-aa
extracellular region
Unlike PSA, PSMA is not a secret protein. Serum
level is very low even elevated. PSMA is membrane
protein, ideal for targeting
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Ovarian Cancer Diagnosis by CA-125
CA-125, a product of the MUC16 gene, is a mucin
made by certain cells in the body which include
those of the uterine tubes, uterus, cervix, and
the lining of the abdominal and chest cavities
CA125 is a membrane glycoprotein that has very
short cytoplasmic domain and a very long
extracellular domain. The cellular function of
the protein is still unknown. The protein exist
in the cells of normal and cancerous tissues of
ovarian.
The release of proteolytic fragments of CA125
leads to elevation of CA125 level in bloodstream,
which is associated with progression of ovarian
cancer and a few other cancer types. The CA125
level can be over 10 folds higher in ovarian
cancer patients compared to the level in normal.
Diagnosis of ovarian cancer is often simple. A
pelvic mass is suspicious and is very often
associated with ovarian cancer. However, when the
pelvic mass is detected, the ovarian cancer
usually has already advanced to quit advanced
stage. There is no symptom for ovarian cancer,
especially during early stage.
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Her-2/neu
The HER (erbB) family member are Growth factor
receptors.
In the HER (erbB) family, only Her-2 did not have
identified ligand.
Expression level correlates with growth of breast
cancer cells.
Diagnostic/prognostic applications. HER2-positive
metastatic breast cancer have a more aggressive
disease, greater likelihood of recurrence, poorer
prognosis and decreased survival.
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Beta-2-microglobulin (b2M)
B2M is the small subunit of the MHC class I
molecule.
How does the protein promotes tumor growth and
metastasis the expression of MHC class 1 in
many tumor cells are repressed.
An hypothesis is that b2M is a signaling molecule
that linked to cell growth and survival pathway.
What are the target of the signal?
Receptors? Known or unknown pathway?
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Biomarker Targeted Imaging
Imaging probe link to a targeting moiety that
target to bio-marker
Basic requirement the marker must presented on
cell surface in high number
Ideally The interaction between marker and
targeting moiety is strong The interaction is
highly specific The target internalization
high payload Distribution at neovasculature,
minimal tissue penetration
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Imaging Targeting PSMA
Antibody is targeting moiety
Antibody conjugated quantum dots
Antibody
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Imaging Targeting PSMA
Antibody conjugated to radio-labels
Patient Images
No resolution hardly tissue image
High sensitivity good for detecting metastasis
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MR Image Target Her-2
Advantage for both Her-2 and PSMA imaging is that
the high number and distribution of the marker in
agiogenesis tissue
Disadvantage for both Her-2 and PSMA imaging is
that the ligand for Her-2 and PSMA are not
identified. Antibodies are the only choice
The levels of both Her-2 and PSMA correlate well
with aggressiveness of disease
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Therapies Target Biomarkers
Simply target the biomarker by antibody
Therapeutic agent link to a targeting moiety that
target to bio-marker
Basic requirement the marker must presented on
cell surface
Ideally The interaction is highly
specific. The target internalization,
accumulation good of agent. Distribution at
neovasculature, minimal tissue penetration. The
level of marker correlate with disease progression
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Therapy Target Her-2
Herceptin
Herceptin binds to HER2-positive cancer cells and
may block them from dividing and growing.
Herceptin attaches to the HER2-positive cancer
cells and may signal the body's immune system to
destroy the cell.
Herceptin can also conjugated with chemotherapy
(paclitaxel) to destroy HER2-positive cancer
cells.
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Herceptin
100
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Mouse
Fused
Humanized
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Mechanism of Herceptin
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Molecular Mechanism for Her-2 Antibody
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Therapy Target Her-2
Small Molecules target HER-2
erlotinib (Tarceva), a kinase inhibitor for
EGFR/HER1 Target HER-2
Affibody target HER-2
Polypeptides of 58 aa derived from IgG binding
domain of protein A, forming a three-helix bundle.
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Therapy Target PSMA
One important advantage is the quick endocytosis
of the PSMA upon the antibody binding.
Due to main neovascular distribution, targeting
of PSMA is very easy, less tissue penetration.
Both Her-2 and PSMA have a good property is
their high level correlate well with
aggressiveness of disease.
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Compounds Target PSMA
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PSMA Target for Tumor Blood Vessel
PSMA is found highly expressed in neovascular of
many cancer types, especially the new vessel in
cancer mass.
PSMA is an excellent target for delivery to many
cancer
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Cancer in Stem Cells or Progenitor Cells
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Cancer Stem Cell Target
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Drugs Target Cancer Stem Cells
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Imaging and Therapeutic Agent
The most significance of the double agent is the
immediately follow the effectiveness of
treatment. Also follow whether the therapies have
been targeted to the sites
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Diagnosis by Proteomic
No single marker can accurately reflecting a
disease. Not even a panel of markers.
We need analyses a large number of disease
markers.