Adding an artificial receptor to T-lymphocytes immune cells boosted their ability to fight a deadly form of cancer called neuroblastoma, the researchers reported.
Neuroblastoma attacks the nervous system. While fairly rare, it accounts for seven percent of all childhood cancers, and 15 percent of non-adult cancer deaths.
In two-thirds of cases, it is not diagnosed until it has already spread to other parts of the body.
In their natural state, T-lymphocytes do not survive very long and lack the molecules that would target cancer cells in tumours.
To overcome this double deficiency, a team of researchers led by Malcolm Brenner at the Baylor College of Medicine in Houston, Texas first selected immune cells naturally stimulated by a common but harmless virus called Epstein-Barr.
They then modified these cells to express a receptor keyed to specific proteins found in human neuroblastoma cells.
"In effect, the T-lymphocytes trampoline off the virus and onto the tumor," said Brenner.
In tests on 11 neuroblastoma patients aged three to 10, the re-engineered immune cells, stimulated by the Epstein-Barr virus, lasted for as long as 18 months, the study reported.
In five cases, tumours regressed and in a sixth the disease receded completely.
"For the first time, we started to see tumour responses," Brenner said. "We have one complete remission and others who have had stable disease for more than a year."
In future research, Brenner and his team plan to add receptors for other cancers to see if they get the same cancer-fighting effect, he said.
The study was published online in the Nature Publishing Group's journal Nature Medicine.