Cancer Biology Tumour Markers Tumour Markers Prof. Kenneth Bagshawe FRS

Tumour Markers Widest Definition Tumour Markers Widest Definition The concept of tumour markers can mean anything that helps in the diagnosis of cancer The concept of tumour markers can mean anything that helps in the diagnosis of cancer In a more restricted sense it refers to the biochemical detection of cancer In a more restricted sense it refers to the biochemical detection of cancer

Imaging Techniques Imaging Techniques Detected by: Detected by: x-ray +/- contrast media x-ray +/- contrast media Ultra sound Ultra sound Computerised Tomography (CT) Computerised Tomography (CT) Magnetic resonance imaging (MRI) Magnetic resonance imaging (MRI) Gamma Camera and radioisotopes Gamma Camera and radioisotopes (Nuclear Medicine) (Nuclear Medicine)

Cannon Ball

Multiple Metastases

Diffuse Metastases-Before and After Chemotherapy

Detection of Tumour Markers Detection of Tumour Markers Those detected on cancer tissue Those detected on cancer tissue i) Biochemical methods i) Biochemical methods Oestrogen receptors in breast cancer Oestrogen receptors in breast cancer ii) Genetic methods ii) Genetic methods Mutated genes BRCA1 and BRCA2 in breast cancer Mutated genes BRCA1 and BRCA2 in breast cancer iii) Antibody methods iii) Antibody methods Carcinoembryonic antigen (CEA) Carcinoembryonic antigen (CEA)

Secreted by cancers into the blood Detection by : Detection by : Biochemical techniques Biochemical techniques steroids in adrenocortical cancer steroids in adrenocortical cancer Immunoassay Immunoassay proteins, glycoproteins proteins, glycoproteins

Ancient History 1848 Bence Jones 1848 Bence Jones Multiple myeloma Multiple myeloma 1929 Ascheim-Zondek 1929 Ascheim-Zondek hCG-trophoblast hCG-trophoblast 1932 Harvey Cushing 1932 Harvey Cushing Pituitary Basophils Pituitary Basophils

The First Tumour Marker It is known as Bence –Jones proteinuria, a marker for multiple myeloma a It is known as Bence –Jones proteinuria, a marker for multiple myeloma a malignancy of the plasma cell. malignancy of the plasma cell. Often referred to as a paraproteinuria Often referred to as a paraproteinuria It is a monoclonal gammopathy with any class of immunoglobulin It is a monoclonal gammopathy with any class of immunoglobulin

Cancers of Endocrine Organs Adrenocortical Adrenocortical Phaeochromocytoma Phaeochromocytoma Insulinoma Insulinoma Gastrinoma Gastrinoma Carcinoid Carcinoid Medullary Ca Thyroid Medullary Ca Thyroid Cortisol Cortisol adrenaline & nor adrenaline adrenaline & nor adrenaline insulin, C peptide insulin, C peptide gastrin gastrin 5-HIAA 5-HIAA Calcitonin Calcitonin

Ectopic product syndromes Cancers sometimes produce substances inappropriate to the cell type of origin Cancers sometimes produce substances inappropriate to the cell type of origin Bronchial carcinomas may produce ACTH, parathormone and Bronchial carcinomas may produce ACTH, parathormone and human Chorionic Gonadotrophin (hCG) human Chorionic Gonadotrophin (hCG)

Protein markers of common cancers detected by immunossay in blood Human Chorionic gonadotrophin (hCG) Human Chorionic gonadotrophin (hCG) Pregnancy Pregnancy Trophoblastic disease - Choriocarcinoma Trophoblastic disease - Choriocarcinoma Germ cell cancers of testis and ovary Germ cell cancers of testis and ovary Alfa- feto protein (AFP) Alfa- feto protein (AFP) Germ cell cancers of testis and ovary Germ cell cancers of testis and ovary Hepatoma Hepatoma

Protein markers continued Carcinoembryonic antigen (CEA) Carcinoembryonic antigen (CEA) Colon, stomach etc Colon, stomach etc Prostate Specific antigen (PSA) Prostate Specific antigen (PSA) CA125- Ovary CA125- Ovary CA153- Breast CA153- Breast

Measurement of Tumour Markers Measurement of Tumour Markers Bioassays on Urine Bioassays on Urine 1958 Immunoassays- serum 1958 Immunoassays- serum 1960 Radioimmunoassay Radioimmunoassay- serum or urine serum or urine 1968 Immunometric assay 1968 Immunometric assay serum or urine- serum or urine- Commercial Kits Commercial Kits 1975 Dip Stick Tests 1975 Dip Stick Tests

What Is An Assay ? Unknown

Antibody Production Immunogen (Antigen) Rabbit Immunogen (Antigen) Rabbit Sheep Antiserum Sheep Antiserum Mouse Mouse Horse etc Horse etc Antisera contain many different antibodies directed at Antisera contain many different antibodies directed at one or more sites on immunogen (polyclonal) one or more sites on immunogen (polyclonal) Burnett (1957)- Clonal selection Theory One Cell - identical antibodies One Cell - identical antibodies

Antibody Production Kohler & Milstein (1975) Kohler & Milstein (1975) Immortalise an antibody producing cell Immortalise an antibody producing cell by fusion with a malignant cell by fusion with a malignant cell Hybridoma Hybridoma Hybridomas proliferate Hybridomas proliferate Identical (monoclonal) antibodies Identical (monoclonal) antibodies

RISING levels of these serum markers indicate disease progression FALLING levels and slowing of rate of increase may indicate response to therapy FALLING levels and slowing of rate of increase may indicate response to therapy BUT interpretation has to take account of the HALF -LIFE (t1/2) BUT interpretation has to take account of the HALF -LIFE (t1/2)

Half Life Of Common Tumour Markers Depends On Molecular Weight MW TM T1/2(D) ROUTE MW TM T1/2(D) ROUTE <70 hCG, PSA 2.3 renal <70 hCG, PSA 2.3 renal 70 aFP 6 mixed 70 aFP 6 mixed > 70 all others 10 hepatic > 70 all others 10 hepatic

Median Doubling Times reflect different growth rates of cancers CANCER TM T2(D) CANCER TM T2(D) Choriocarcinoma hCG 3 Choriocarcinoma hCG 3 Germ cell aFP 6 Germ cell aFP 6 Breast CA153, CEA 30 Breast CA153, CEA 30 Ovary CA Ovary CA Pancreas CA Pancreas CA Colon CEA, CA Colon CEA, CA Prostate PSA 128 Prostate PSA 128

Cell Numbers

Time Scale- Cell Numbers

Human Chorionic Gonadotrophin- (HCG) C-Terminal Peptide

Normal Placental Villi

hCG V Cell Numbers

Human Chorionic Gonadotrophin (hCG) Normal Pregnancy: Mostly Intact molecule (α and β subunits) Mole, Choriocarcinoma: Fragmented hCG molecules

Trophoblastic Tumour

Choriocarcinoma

Germ Cell Tumour

Prostate Specific Antigen (PSA): Age Effect

Carcinoembryonic Antigen

CEA

Radioimmunolocalisation-CEA

Therapeutic Application Radiolabelled Antibodies (RIT) Drug-Antibody Conjugates

Problems Only a fraction of the i.v injected antibody gets into tumour: Only a fraction of the i.v injected antibody gets into tumour: Most of the antibody stays in blood until excreted or metabolised Most of the antibody stays in blood until excreted or metabolised Heterogeneity of cancer cell: Heterogeneity of cancer cell: not all cancer cells express the marker not all cancer cells express the marker

Potential Solutions Antibody directed enzyme prodrug therapy (ADEPT) Antibody directed enzyme prodrug therapy (ADEPT)