Advance gene therapy

1. Advances In Gene Therapy
Presented by
Mahendra G S
M.pharm
Pharmaceutical
chemistry

2. A Brief history of gene therapy
Advances in biochemistry and molecular
biology have helped to understand the
genetic basis of inherited diseases.
 gene therapy was once considered a
fantasy
(imaginary)
It was a dream of researchers to replace
the
defective genes with good ones and cure
the
genetic disorder

3. Contd….
 However, thousands of individuals
already undergone human clinical
trials.
 A great leap in medical science has
taken place on the 14th sept 1990,
when a girl suffering from adenosine
deaminase deficiency (severe
combined immunodeficiency) was
treated by transferring the normal
gene for adenosine deaminase.

4. What is gene therapy
 Gene therapy is the process of inserting genes into
a person’s cells to treat or prevent disease.
 The newly introduced gene will encode proteins
and correct the deficiencies that occur in genetic
disease
 It is a novel approach to treat, cure, or prevent
disease by changing the expression of a
person's genes.
 In the future, this tech may allow doctors to treat
disease by inserting genes instead of drugs or
surgery

5. Gene therapy stategies
1. Gene augmentation therapy
 A DNA is inserted to the genome to
replace missing gene product.
2. Gene inhibition therapy
 The antisense gene inhibits the
expression of the dominant gene.

7. Approaches for gene therapy
1. Somatic cell gene therapy
• The non-reproductive cells of an
organism are referred to as somatic
cells.
• These are cells of organism other
than sperm or egg cells.
eg: bone marrow cell,blood cells,skin
cell,intesinal cell.

8.  At present, all the research on gene
therapy is directed to correct the
genetic defect in somatic cells.
 It involves the insertion of a fully
functional and expressible gene into a
target somatic cell to correct a genetic
disease permanently.

9. 2. Germ cell gene therapy
 the reproductive cells of organism
constitute germ cell line.
 Gene therapy involving the
introduction of DNA into germ cell is
passed on to the successive
generation.
 Due to ethical and technical reason,
germ cell gene therapy is not being
attempted at present.

10. Types of gene therapy
 Ex vivo gene therapy
involves the transfer of genes in
cultured cells (e.g: bone marrow
cell) which are then introduced into
patient.
 In vivo gene therapy
the direct delivery of genes into the
cells of a particular tissue is referred to
as in vivo gene therapy

12. Gene Therapy Depends on
Delivery of Corrective Genes
 Viral vectors are a tool commonly
used by molecular biologists to deliver
genetic material into cells.
 This process can be performed inside
a living organism (in vivo) or in cell
culture (in vitro).
 Viruses have evolved specialized
molecular mechanisms to efficiently
transport their genomes inside the
cells they infect

13. Viruses are used as vectors
 Viruses are used as vectors to
introduce the genetic material inside
the bodies.
These viruses are inactivated, they
are not able to reproduce
1. Adenoviruses
2. Adeno-associated virus
3. Herpes viruses -DNA tumor viruses
4. Retroviruses -RNA tumor viruses

14. 5. Lenti virus
6. Pox viruses
7. Measles viruses
Immunogenicity: ability to produce
immune response

15. Nonviral Vectors:
 Liposomes less Immunogenic
DNA/lipid complexes are easy to prepare and
there is no limit to the size of genes that can
be
delivered. Because carrier systems lack
proteins, they may evoke much less
immunogenic responses.
More importantly, the cationic lipid systems
have much less risk of generating the
infectious form or inducing tumorigenic
mutations because genes delivered have low
integration frequency and cannot replicate or

16. Nanotechnology in Gene therapy
 Nanotechnology", is the study of the
control of matter on an atomic and
molecular scale. Generally
nanotechnology deals with structures
of the size 100 nanometers or smaller,
and involves developing materials or
devices within that size The
nanotechnology-based approach used
by the researchers has minimal toxic
side effects to normal cells

17. First Approved Gene Therapy
 On September 14, 1990 at the U.S.
National Institutes of Health, by W.
French
Anderson M.D. and his colleagues
performed the first approved gene
therapy procedure on four-year old
Ashanthi DeSilva, Born with a rare
genetic disease called severe
combined immunodeficiency (SCID)

18. What did they do
 In Ashanthi's gene therapy procedure,
doctors removed white blood cells
from the child's body, let the cells grow
in the laboratory, inserted the missing
gene into the cells, and then infused
the genetically modified blood cells
back into the patient's bloodstream.

20. 'mending broken hearts' by using
gene therapy
Novel techniques to “mend broken hearts”
using gene therapy and stem cells
represent a major new development in the
treatment of heart disease
 It was achieved by the researchers at
Gladstone Institute of Cardiovascular Disease
in California
 They were able to re-programme scar-forming
cells into heart muscle cells, some of which
were capable of transmitting the kind of
electrical signals that make the heart beat
 They performed on a live mice, transforming
scar-forming cells, called fibroblasts, into
beating heart muscle cells

21. Contd…
 They injected three genes (cocktail of
genes) into the heart of live mice that
had been damaged by heart attack,
fibroblasts could be turned into
working heart cells.
 Researchers said that the “cocktail of
genes” used to regenerate cells could
one day be replaced with “small drug-
like molecules” that would offer safer
and easier delivery

22. First Real-Time MRI-Guided
Gene Therapy for Brain Cancer
 Neurosurgeons at the University of California
and San Diego School of Medicine are among
the first in the world to utilize real-time magnetic
resonance imaging (MRI) guidance for delivery
of gene therapy as a potential treatment for
brain tumors
 Using MRI navigational technology,
neurosurgeons can inject Toca 511
(vocimagene amiretrorepvec), a novel
investigational gene therapy, directly into a
brain malignancy
 The new approach offers a precise way to
deliver a therapeutic virus designed to make

23.  Toca 511 is a retrovirus engineered to
selectively replicate in cancer cells, such
as glioblastomas.
 Toca 511 produces an enzyme that
converts
an anti-fungal drug, flucytosine (5-FC),
into
the anti-cancer drug 5-fluorouracil (5-
FU).
 After the injection of Toca 511, the
patients
are treated with an investigational
extended-
release oral formulation of 5-FC called

24. stem cell gene therapy gives
hope to
prevent inherited neurological
disease
Scientists from The University of
Manchester have used stem cell gene
therapy to treat a fatal genetic brain
disease
 It was used to treat Sanfilippo – a fatal
inherited condition which causes progressive
dementia in children
 Sanfilippo, is currently untreatable
mucopolysaccharide (MPS) disease
 It is caused by the lack of SGSH enzyme in
the body which helps to breakdown and
recycle long chain sugars, such as heparan

25. Contd..
 Children with the condition build up
and store excess HS throughout their
body from birth which affects their
brain and results in progressive
dementia and hyperactivity, followed
by losing the ability to walk and
swallow

26. Mucopolysaccharidosis Type IIIA
potential gene therapy
 Mucopolysaccharidosis Type IIIA
(MPSIIIA) is a metabolic disorder in
which the body is missing an enzyme
that is required to break down long
chains of sugars known as
glycosaminoglycans
 The glycosaminoglycans collect in the
body and cause damage, particularly in
the brain if not broken
 Fàtima Bosch and colleagues at
Universitat Autònoma de Barcelona in
Spain developed a form of gene therapy
to replace the enzyme that is missing in

27. Contd..
 They injected the replacement gene
into the cerebrospinal fluid that
surrounds the brain and spinal cord
 This study demonstrates that gene
therapy can be delivered to the brain
through the cerebrospinal fluid and
suggests that this approach could
potentially be used as a therapy for
MPSIIIA

28. IS GENE THERAPY TOTALLY
SAFE ??
 Although gene therapy is a promising
treatment option for a number of
diseases (including inherited disorders,
some types of cancer, and certain viral
infections), the technique remains risky
and is still under study to make sure that
it will be safe and effective.
 Gene therapy is currently only being
tested for the treatment of diseases that
have no other cures

29. Technical Difficulties in Gene
Therapy
 Gene delivery: Successful gene delivery is not
easy or predictable, even in single-gene
disorders.
 For example, although the genetic basis of
cystic fibrosis is well known, the presence of
mucus in the lungs makes it physically difficult
to deliver genes to the target lung cells.
 Delivery of genes for cancer therapy may also
be complicated by the disease being present at
several sites.
 Gene-therapy trials for X-linked severe
combined
immunodeficiency (X-SCID), however, have
been more successful

30. Problems with Gene Therapy
 Short Lived
Hard to rapidly integrate therapeutic DNA into genome
and rapidly dividing nature of cells prevent gene therapy
from long time Would have to have multiple rounds of
therapy
 Immune Response
new things introduced leads to immune response
Increased response when a repeat offender enters
the gene might be over-expressed (toxicity)
 Viral Vectors
Patient could have toxic, immune, inflammatory
response
also may cause disease once inside

31.  Multigene Disorders
Heart disease, high blood pressure,
Alzheimer’s, arthritis and diabetes are
hard to treat because you need to
introduce more than one gene

33. reference
 biochemistry by u. sathyanarayan,
page:no 625-630
 https://www.nature.com/subjects/gene-
therapy
 http://stm.sciencemag.org/content/2/38/3
8ec102
 http://biologywriter.com/on-
science/articles/genetherapy/
 http://onlinelibrary.wiley.com/doi/10.1111/j
.1365-2036.2010.04424.x/full

34. Thank you