In Amazon, a frustrated search for cancer cures
Researchers say Amazon could yield cancer
breakthrough:
Some 70 extracts show promise; more tests needed:
Stuart GRUDGINGS
The task of harvesting the secrets of Brazil's vast Amazon rain
forest that could help in the battle against cancer largely falls to
Osmar Barbosa Ferreira and a big pair of clippers.
In jungle so dense it all but blocks out the sun, the lithe
46-year-old shimmies up a thin tree helped by a harness, a strap between
his feet, and the expertise gained from a lifetime laboring in the
forest.
Osmar Barbosa Ferreira climbs a tree to collect plants in Sao
Sebastiao de Cuieiras near the Cuieiras river in the Brazil’s
Amazon rain forest October 30, 2009. Finding the right material
is no easy task in the world’s largest rain forest that can have
up to 400 species of trees and many more plants in a 2.5-acre
(1-hectare) area, and in a country where suspicion of outside
involvement in the Amazon runs strong. Picture taken on October
30, 2009. GETTY images |
A few well-placed snips later, branches cascade to a small band of
researchers and a doctor who faithfully make a long monthly trip to the
Cuieiras river in Amazonas state in the belief that the forest's
staggeringly rich plant life can unlock new treatments for cancer. They
may be right.
About 70 percent of current cancer drugs are either natural products
or derived from natural compounds, and the world's largest rain forest
is a great cauldron of biodiversity that has already produced medicine
for diseases such as malaria. But finding the right material is no easy
task in a forest that can have up to 400 species of trees and many more
plants in a 2.5-acre (1-hectare) area, and in a country where suspicion
of outside involvement in the Amazon runs strong.
"If we had very clear rules, we could attract scientists from all
over the world", said the doctor, Drauzio Varella, with a mix of
enthusiasm and frustration. "We could transform a big part of the Amazon
into an enormous laboratory".
As it stands, though, foreigners are barred from helping oncologist
Varella and the researchers from Sao Paulo's Paulista University, who
are among a tiny handful of Brazilian groups licensed to study samples
from the Amazon.
Varella, 66, believes his high profile has helped. He is a well-known
writer and television personality who shot to fame in 1999 with a book
and subsequent hit movie based on his work as a doctor in a brutal Sao
Paulo prison called Carandiru.
But a move by his team in the 1990s to partner with the US National
Cancer Institute produced a storm of accusations of 'bio-piracy' and for
years it has been blocked from the international cooperation and funding
that could increase the chances of finding the Holy Grail of a cancer
cure.
Their work has also been regularly delayed by bureaucratic demands,
once stopping their collections for two years.
In more than a decade of searching, the group has brought back 2,200
samples from this tributary of the mighty, tea-dark Rio Negro (Black
River) to its laboratory in Sao Paulo, of which about 70 have shown some
effect against tumors.
Just those samples have given the team enough analysis work for 20
years, said Varella, a lanky marathon runner whose younger brother died
of cancer.
"If we can find 70, imagine what a big university with international
resources could do, they could screen for an absurd amount of diseases",
said Varella, who still spends part of his time treating prisoners in
Sao Paulo.
"As well as the impact this could have on human health, it could
bring resources for preservation and to improve the quality of life of
people who live here".
Ironically, it was a foreigner who inspired Varella to begin his
search. Robert Gallo, a US researcher and leading AIDS expert who
co-discovered the HIV virus, asked Varella during a trip to the Amazon
in the early 1990s if anyone was researching the medical potential of
the forest.
Jigsaw puzzle
Among the natural products being used to fight cancer today is Taxol,
a chemotherapy drug that comes from the bark of the Pacific yew tree.
David Newman, head of the Natural Products Branch of the US National
Cancer Institute, said several promising cancer drugs derived from
natural sources as varied as a deep-water sponges and microbes are
currently going through clinical trials. Often the natural compounds are
tweaked or mimicked to better fight cancer cells.
"It's a detective story and a jigsaw puzzle, but you don't know how
many pieces there are or what the picture looks like", he said. "In one
teaspoon of soil from the Amazon, you find over a thousand microbes that
have never been isolated".
Out of an estimated 80,000 species of flower-bearing plants in the
Amazon, only about a fifth have been identified.
Newman said progress in Brazil has been greatly hampered by the
inability of companies to patent a natural product under legislation
passed in the 1990s, leaving no incentive to invest in research.
He cited the example of a Brazilian viper snake whose venom proved
vital to the development of blood pressure drug captopril in the 1970s,
a find that might not have happened under today's laws.
Further analysis of the promising compounds found by Varella's team
has been held up while the university waits for access to a
nuclear-magnetic resonance machine that can isolate the active elements.
"We're still a long way from discovering an actual medicine that
could cure a type of cancer but we have strong signs that some plants
have substances that inhibit the growth of tumors", said Mateus
Paciencia, a bearded 34-year-old botanist.
Reuters |