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Newer cancer therapiesNewer cancer therapies
ImmunotherapyImmunotherapyAngiotherapy Angiotherapy Gene therapyGene therapy
ImmunotherapyImmunotherapy
ImmunotherapyImmunotherapy
ImmunotherapyImmunotherapy Non-specific immunotherapyNon-specific immunotherapy
BCG BCG CytokinesCytokines Cell therapyCell therapy
Specific immunotherapySpecific immunotherapy adoptive adoptive
Antibody therapyAntibody therapy Adoptive transfer of T cellsAdoptive transfer of T cells
VaccinationVaccination Tumour-based vaccinesTumour-based vaccines Virus-based vaccinesVirus-based vaccines Peptide-based vaccinesPeptide-based vaccines othersothers
ImmunotherapyImmunotherapy
ImmunotherapyImmunotherapy
ImmunotherapyImmunotherapy
AngiotherapyAngiotherapy
Key differences in tumour Key differences in tumour vasculaturevasculature
Different flow Different flow characteristics / characteristics / blood volumeblood volume
Microvasculature Microvasculature permeabilitypermeability
Increased Increased fractional fractional volume of volume of extravascular, extravascular, extracellular extracellular spacespace
Angiogenesis-overviewAngiogenesis-overview Balance between inhibitory factors (endostatin) and angiogenic factors (VEGF, bFGF)
angiogenic factors stimulate MMPs and plasminogen activators
Degradation of basement membrane
Invasion and differentiation of endothelial cells in surrounding tissues
Before treatment after treatment
BLOOD FLOW
MMPIsMMPIs
Disappointing results with matrix Disappointing results with matrix metalloproteinase inhibitors metalloproteinase inhibitors
Poor survival rate in phase III clinical trials Poor survival rate in phase III clinical trials against renal cell carcinomaagainst renal cell carcinoma
Newer cancer therapiesNewer cancer therapiesGene therapyGene therapy
Severe Combined Immunodeficiency Disease (SCID)
Antisense therapy Antisense therapy (suppress gene expression)(suppress gene expression)
Gene augmentation Gene augmentation (supplement defective gene)(supplement defective gene)
Gene therapyGene therapy
Antisense therapyAntisense therapycompensates for genetic compensates for genetic
mutations that produce mutations that produce destructive proteinsdestructive proteins
Main strategies involved areMain strategies involved are
1) short stretches of synthetic 1) short stretches of synthetic DNA that target the mRNA DNA that target the mRNA transcripts of abnormal transcripts of abnormal proteins preventing its proteins preventing its translation ORtranslation OR
small RNA molecules small RNA molecules (siRNA) used to degrade (siRNA) used to degrade aberrant RNA transcriptsaberrant RNA transcripts
Antisense therapyAntisense therapy
2) provide a gene for a 2) provide a gene for a protein (intracellular protein (intracellular antibody) that can antibody) that can block the activity of the block the activity of the mutant proteinmutant protein
Tumor necrosis therapy utilizes monoclonal antibodies targeting intracellular tumor antigens on necrotic (dead) tissue. This method overcomes some of the limitations of current antibody-based therapeutic approaches
3)3) design hybrids of design hybrids of DNA / RNA that DNA / RNA that might direct repair of might direct repair of the mutant gene the mutant gene
Gene augmentationGene augmentationmost therapies simply add a useful gene into a most therapies simply add a useful gene into a
selected cell type to compensate for the missing or selected cell type to compensate for the missing or flawed version or even instil an entirely new flawed version or even instil an entirely new version. version.
Direct approach Direct approach
inducing cancer cells to make a protein that will kill inducing cancer cells to make a protein that will kill the cell. the cell.
Indirect approach Indirect approach
stimulating an immune response against selected stimulating an immune response against selected cells or eliminating the blood supply. cells or eliminating the blood supply.
deliverydelivery
3 challenges in gene therapy3 challenges in gene therapy
deliverydelivery deliverydelivery
1)1) Package the genePackage the gene2)2) Protect the geneProtect the gene3)3) deliver to the nucleus and release deliver to the nucleus and release
in an active formin an active form
Vectors ‘Trojan horses’ that sneak the gene into the cell
Carrier molecules designed Carrier molecules designed specifically to enter cells & deposit specifically to enter cells & deposit
therapeutic genestherapeutic genes
Vectors can be viral or non-viral Vectors can be viral or non-viral
VectorsVectors
METHODS OF VECTOR DELIVERYMETHODS OF VECTOR DELIVERY
Viral vector strategyViral vector strategyReplication & virulence genes can be Replication & virulence genes can be
substituted with therapeutic genessubstituted with therapeutic genes
designed to enter cell and deposit genesdesigned to enter cell and deposit genes
Problems Problems of retroviral therapy includeof retroviral therapy include
Lack of cell specificity:Lack of cell specificity: Promiscuous: depositing genes into Promiscuous: depositing genes into several cell types resulting in reduced several cell types resulting in reduced target efficiency and unwanted target efficiency and unwanted physiological effectsphysiological effects
Random splicing into host DNARandom splicing into host DNA resulting in normal gene disruption resulting in normal gene disruption and/or alteration in gene function and/or alteration in gene function
Retroviral vectorsRetroviral vectors
Adenoviral vectorsAdenoviral vectors
do not insert into genome
temporary
lack of specificity
strong immune response
Adeno-associated viral vectorsAdeno-associated viral vectors
Nature Reviews Genetics 1; 91-99 (2000);
Integrate into genome but small in size
AdvantagesAdvantages
non-toxicnon-toxic
no immune responseno immune response
Non-viral VectorsNon-viral Vectors
Tumour-suppressor gene deliveryTumour-suppressor gene delivery
Nature Reviews Cancer (2001) Vol 1; 130-141
Delivery of agents that block Delivery of agents that block oncogene expressiononcogene expression
Nature Reviews Cancer (2001) Vol 1; 130-141
Suicide gene deliverySuicide gene delivery
Nature Reviews Cancer (2001) Vol 1; 130-141
Conditionally replicating virusesConditionally replicating viruses
Non-viral VectorsNon-viral Vectors
liposomes (lipoplexes)liposomes (lipoplexes)
amino acid polymers: cationic polymers amino acid polymers: cationic polymers
e.g. B-cyclodextrinse.g. B-cyclodextrins
Non-viral VectorsNon-viral Vectors
naked DNA naked DNA
artificial human chromosomes artificial human chromosomes
Non-viral VectorsNon-viral Vectors Gene gun
SuccessesSuccesses Cancer and the p53 gene. Researchers used a virus to carry a normal
copy of the p53 gene into the abdominal and pelvic areas of women with advanced ovarian cancer. Seven of 25 women tested in California and Iowa survived more than 2 years after the therapy, despite having a terminal diagnosis.
Cancer and enzyme therapy. This type of therapy targets enzymes, or proteins, that are made by abnormal genes. Example: Gleevec, a new drug, targets an abnormal protein produced by a cancer-causing gene. The abnormal protein is necessary for some types of cancer to survive and reproduce. Gleevec blocks the action of the protein. Gleevec has been successful in chronic myeloid leukemia and in gastrointestinal stromal tumors. It is being tested in other types of cancer.
Cancer and other therapies. Advances in identifying genes have helped researchers to target other therapies. Example: Herceptin targets the HER-2 gene. In 25%-35% of breast cancers, HER-2 produces too many copies of itself, causing breast cancer cells to reproduce out of control and spread throughout the body. Herceptin blocks excess HER-2 by binding to growth receptors on the surface of the cell, causing tumors to shrink.
Gleevec for chronic myeloid leukaemia (CML)Gleevec for chronic myeloid leukaemia (CML) CML results through a chromosomal rearrangement that fuses two genes CML results through a chromosomal rearrangement that fuses two genes
together. This produces an oncogene that encodes an enzyme, a form of together. This produces an oncogene that encodes an enzyme, a form of tyrosine kinase known as tyrosine kinase known as BCR-ABL.BCR-ABL. Unchecked production of that enzyme Unchecked production of that enzyme leads to excessive levels of white blood cells in the blood and bone marrow. leads to excessive levels of white blood cells in the blood and bone marrow. that disrupts the normal production of white blood cells. that disrupts the normal production of white blood cells.
Gleevec works specifically to block the activity of that form of tyrosine Gleevec works specifically to block the activity of that form of tyrosine kinase. kinase.