Good news: a drug which attacks cancerous cells but leaves the healthy tissues untouched has been developed; but till now only mice have counted its blessings
WHILE anti-cancer drugs kill turnout
cells, healthy tissues in the patient's
body cannot escape the chemical crossfire. This leads to vicious side effects that
sometimes lead the doctor to halt the
treatment before completion of the
dosage. Scientists have now come up
with a solution to this problem. A drug
has been developed that targets features
unique to cancerous cells, thereby
causing minimal harm to healthy
tissues in the body. (New Scientist,
Vol 149, No 2013).
The mechanism that the anti-cancer
drugs adopt to kill the turnour cells
involves destroying DNA in these fast
dividing cells. But as some normal cells
also divide rapidly, they may also be targeted by the drugs currently used in
conventional chemotherapy. Cells from
the bone marrow, hair follicles and the
lining of the gut also divide fast; therefore, the result of the growth restricting
anti-cancer drug is imaginable. The
condition can further be aggravated by
another problem - the cancer cells becoming resistant to the drug.
Scientists at the Cell Therapeutics
Incorporated (CTI), a Seattle-based
company in the us, developed the new
drug that has been christened CT-2584.
The drug takes a different line of
attack, It targets phosphaticlic acids the
molecules with a level in tumour cell as
high as 10 to 15 times as compared to
the normal cells. This ensures that the
normal cells are not so sensitive to
drugs.
The drug stimulates an enzyme
called phosphotidyl-choline phospholipase-D, which is involved in manufacturing phosphaticlic acids. This leads to
a phenomenal rise in the level of
phosphaticlic acid in the turnout cells,
that already have an abnormally high
level of it, to the point where they start
destroying the cells.
The mode of destruction of the
turnout cells by high levels of phosphatidic acids is interesting. It sets
off a chain of reactions that burst
the membranes in the mitochondria of
the cells.
Mitochondria are chambers inside a
cell that store and distribute energy
within it. Called the "powerhouse" of
the cell, these organelles, when exposed
to the new drug are rendered disabled.
Cell death becomes inevitable as a result
of it. After screening CT-2584 against
cells derived from 65 types of cancers, it
was found that "in each one, the killing
effect was at the same dose", as reported
by Jim Bianco, president of CTI
Researchers thus confirmed that the
mechanism of cell death was same for all
types of turnour cells derived from different types of cancer.
Besides rupturing the cancer cell's
energy stores, CT-2584 also kills cells
resistant to other chemotherapy drugs.
Found very effective in preclinical trials
on mice with aggressive forms of lung,
skin and colon cancer, the next step is to
see its effect on the humans. The first
human trials shall be conducted on
around 30 patients, in the UK, with
advanced cancer by Malcom Ranson on
behalf of the Cancer Research
Campaign.
Additional trials will be conducted
in the US. The drug has evoked widespread optimism and interest among
the scientists. Tom Conners of the
University of London's School of
Pharmacy reflects the feeling aptly: The
new drug is of great interest because of
its unique mode of action, and it is right
that it should be looked at in the
clinic. Tested successfully on mice, let US
hope the drug does wonders on humans
too.
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