CAR T - CELL THERAPY - SCIENCE AND TECHNOLOGY
News: Explained
| Why CAR T-cell therapy is cancer treatment’s next moonshot
What's in the news?
● A
new development on the systemic therapy front, currently holding the attention
of many researchers worldwide, is CAR T-cell therapy.
Types of Cancer therapy:
● Surgery - Removing
the cancer cells.
● Radiotherapy - Delivering
ionizing radiation to the tumour.
● Systemic therapy - Administering
medicines that act on the tumour.
Types of Systemic therapy:
1. Chemotherapy:
● Systemic
therapy’s earliest form was chemotherapy - when administered, it preferentially
acts on cancer cells because of the latter’s rapid, unregulated growth and poor
healing mechanisms.
● Chemotherapeutic
drugs have modest response rates and
significant side-effects as they affect
numerous cell types in the body.
2. Immunotherapy:
● The
drugs bind to specific targets on the cancer or in the immune cells that help
the tumour grow or spread.
● This
method often has fewer side-effects as the impact on non-tumour cells is
limited.
● However,
it is effective only against tumours that express these targets.
3. CAR T-cell Therapy:
● Chimeric
antigen receptor (CAR) T-cell therapies represent a quantum leap in the
sophistication of cancer treatment.
● Unlike
chemotherapy or immunotherapy, which require mass-produced injectable or oral
medication, CAR T-cell therapies use a
patient’s own cells.
● They
are modified in the laboratory to activate T-cells, a component of immune
cells, to attack tumours.
● These
modified cells are then infused back into the patient’s bloodstream after
conditioning them to multiply more effectively.
● The
cells are even more specific than
targeted agents and directly activate the patient’s immune system against
cancer, making the treatment more clinically
effective. This is why they’re called “living
drugs”.
How does it work?
● In
CAR T-cell therapy, the patient’s blood is drawn to harvest T-cells – immune
cells that play a major role in destroying
tumour cells.
● Researchers
modify these cells in the laboratory so that they express specific proteins on
their surface, known as chimeric antigen receptors (CAR) - they have an
affinity for proteins on the surface of tumour cells.
● This
modification in the cellular structure allows CAR T-cells to effectively bind
to the tumour and destroy it.
○ Conventional chemotherapy
or immunotherapy comprises molecules that bind to the
tumour or block chemical pathways that allow the tumour to grow or multiply –
but don’t directly affect the immune
system.
● In
CAR T-cell therapy, the immune system is
activated when the modified T-cells are reintroduced into the body, which
allows a gradual and sustained tumour kill as these cells multiply.
Applications:
● As
of today, CAR T-cell therapy has been approved for leukaemias (cancers arising from the cells that produce white blood
cells) and lymphomas (arising from
the lymphatic system).
● CAR
T-cell therapy is also presently used among patients with cancers that have
returned after an initial successful treatment or which haven’t responded to
previous combinations of chemotherapy or immunotherapy.
Response of CAR T-cell therapy:
● Its
response rate is variable. In
certain kinds of leukaemias and lymphomas, the efficacy is as high as 90%,
whereas in other types of cancers it is significantly lower.
● The
potential side-effects are also significant, associated with cytokine release syndrome (a widespread
activation of the immune system and collateral damage to the body’s normal
cells) and neurological symptoms (severe confusion, seizures, and speech
impairment).
● It
is unaffordable to half of the Indians as it is costly.