Washington: A way of fighting cancer that turns the body's immune cells into targeted tumor killers was named the breakthrough of the year by the US journal Science today.
Immunotherapy has only worked for a small number of patients, and only in certain cancers, including melanoma and leukemia, but experts believe its promise is huge.
"Oncologists, a grounded-in-reality bunch, say a corner has been turned and we won't be going back," said the journal Science.
Research began in the late 1980s when French scientists discovered a receptor on T-cells, called CTLA-4, a molecule that turned out to play an important role in regulating the immune system.
A decade later, a Texas researcher showed that blocking CTLA-4 in mice "could unleash T-cells against tumor cells in the animals, shrinking them dramatically," the journal said.
More advances have followed. In the 1990s, a biologist in Japan discovered a molecule expressed in dying T-cells, called PD-1, which has also shown promise in the fight against cancer.
As many as five big pharmaceutical companies are now on board with immunotherapy. A new drug made by Bristol Myers-Squibb was approved in 2011. Called ipilimumab, it costs USD 120,000 per treatment course.
It's costly, and by no means a sure bet. Research in 2012 on a group of 300 people showed the drug shrunk tumors by half or more in 31 per cent of patients with melanoma, 29 per cent with kidney cancer and 17 per cent with lung cancer.
Research out this year on 1,800 people with melanoma who received ipilimumab, 22 per cent were alive three years later.
A related treatment called chimeric antigen receptor therapy, which involves modifying a patient's own T-cells to make them attack tumors, has succeeded in putting 45 of 75 people with leukemia in total remission, researchers said this year.
One of those success stories is Emily Whitehead, now age eight. Last year she became the first pediatric patient to receive the experimental therapy for acute lymphoblastic leukemia (ALL).
"She is doing great. She is almost 20 months cancer free now. Her health has just been wonderful. She is completely back to normal, back to school full time," her mother, Kari, told AFP.
Emily was at the brink of death, and after two relapses doctors admitted they had no options. Their hope was suddenly revived when her family learned about the experimental T-cell therapy and agreed to try it.