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Gold dots, great hopes

Gold dots, great hopes
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First Published: Fri, Apr 22 2011. 01 15 AM IST
Updated: Sat, Jul 02 2011. 02 11 PM IST
We have heard a lot about the Pulitzer prize for Siddhartha Mukherjee, author of The Emperor of All Maladies, an evocative biography of cancer. But we rarely hear as much of the quiet battle against the disease.
Cancer is a disease from within. Normal cells grow and die. Cancerous cells cannot stop growing. They become malignant, destroying tissue around them and often spreading through the body. As Mukherjee notes, malignant growth and normal growth “are so genetically intertwined that unbraiding the two might be one of the most significant scientific challenges faced by our species”.
The desire for a longer and better life has caused the identification of a class of carcinogens, from cigarette smoke to pollutants in air, water and food. These carcinogens cause mutations in genes that regulate cell growth, sending them on an immutable quest to recreate the human body in their cancerous image.
So, cancer threatens to be a 21st century contagion, a malady spawned chiefly by environmental factors—less than 10% of cancers are hereditary—and helped by aging, longer-living populations. “If we seek immortality,” says Mukherjee, “then so, too, in a rather perverse sense, does the cancer cell.”
The rather difficult scientific trick, then, is to quell cancer’s quest for immortality. An important way to do that is to catch cancers early. If that can be done, many can be cured.
This is where people like Sanjiv “Sam” Gambhir come in. Gambhir (47), director of the Molecular Imaging Program at Stanford University, published a paper in the journal Science Translational Medicine a day before the Pulitzer announcement, taking forward this idea: Like tiny detectives, invisible particles can travel through the body finding and fixing previously undetectable tumours.
Gambhir and his team use nanoparticles just 100 nanometres across, or 0.000001 mm. A synthesis of gold and silica (the primary raw material for glass), these already have a real-world application. Embedded in currency notes, the gold dots allow detection of counterfeits. When scanned, they scatter light in unique patterns, like a fingerprint.
Unique to every type of molecule, this fingerprinting by light was first revealed by Chandrasekhara Venkata Raman, the Indian physicist who won the Nobel prize for physics 81 years ago for his work on the same subject.
Using what is called Raman spectra or Raman imaging, Gambhir’s team has previously shown the gold dots work. It now proved that the dots are safe to use in mice. Little is known about their effects on humans. “We are about 18 months from human trials,” Gambhir told me.
Gambhir and his team are working on colorectal cancer, injecting the gold dots into mice through their rectum or the tail vein. This allows the dots to seep into the liver, spleen and bone marrow. The dots have hook-shaped peptides, or specific molecules, that attach themselves to polyps, or abnormal cells. Many small or flat polyps currently escape detection during endoscopy, scans for colorectal cancer.
The gold dots can be used in other cancers, says Gambhir. “For human use, they would be sprayed into the bowel during colonoscopy or eventually just by drinking. For non-colorectal cancer applications they would be injected into a human vein (so they could spread through the body).”
Other teams are working on tools that adopt a similar micro-target approach against cancer. Present-day chemotherapy debilitates patients because it devastates healthy tissue along with cancerous cells. Two months ago, researchers at the Penn State College of Medicine in the US used molecule-sized bubbles filled with chemotherapy drugs to kill abnormal cells in test tubes and mice.
There is so much potential seen in the relatively new field of molecular imaging that Gambhir is a founder, investor or consultant to 10 biotechnology companies, including one called Enlight Biosciences, a Boston-based venture fund set up in 2008 with support from six of the biggest pharma companies. Apart from Gambhir, Enlight’s scientific advisory board has Rakesh Jain, a professor of tumour biology at Harvard Medical School, and Raju Kucherlapati, a professor of medicine at Harvard. Its chairman is Robert Horovitz, a professor of biology at Massachusetts Institute of Technology and Nobel-prize winner. The idea: coax pharma companies to jointly develop technologies for medical needs unaddressed by emerging science.
Such pooling of intellect and resources was inevitable in an industry where scaling up advances such as gold dots for human use is now a fraught endeavour. In the last 10 years, the world’s largest pharma companies have spent $480 billion to get just 85 products approved.
So, while the future holds promise, a triumph over cancer is a long way off.
Lance Armstrong, the champion cyclist who overcame life-threatening cancer, once said he was more proud of his victory over the disease than of his unrivalled seven victories in the Tour de France cycle race. “When you think about it, what other choice is there but to hope?” said Amstrong. “We have two options, medically and emotionally: give up, or fight like hell.”
Samar Halarnkar is editor-at-large,Hindustan Times.This is a fortnightly column that explores the cutting edge of science and technology. Comments are welcome at frontiermail@livemint.com
To read Samar Halarnkar’s previous columns, go to www.livemint.com/frontiermail
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First Published: Fri, Apr 22 2011. 01 15 AM IST