Researchers Develop ‘Smart Bomb’ to Seek Out, Kill Leukemia Cells
WASHINGTON — Researchers experimenting with mice have created a cancer “smart bomb” that attacks and kills leukemia cells without harming normal cells.
Dr. F. M. Uckun of the University of Minnesota in Minneapolis said Thursday that the “smart bomb” is actually an antibody that will attach to a receptor molecule found only on the surface of leukemia cells.
“The antibody is the missile,” said Uckun, and hooked to the missile is the payload--a chemical that actually kills the leukemia cell.
Uckun, first author of a study appearing Friday in the journal Science, said the same “smart bomb” technique for the targeted delivery of a killing chemical can also be used for some cancers of the breast, ovaries and brain. The technique may be tested on humans this summer.
In the study, Uckun and his team injected human leukemia cancer cells into laboratory mice that have no immune system. The cancer, called B-cell precursor leukemia, is the most common form of childhood cancer and the second most common form of acute leukemia in adults.
Uckun said earlier studies have shown that a molecule called protein tyrosine kinase is essential for the survival of leukemia cells. Studies also have shown that a synthetic chemical called genistein could block the action of the kinase.
But the problem was how to get the genistein inside the cancer cells. And the solution was the “smart bomb.”
Uckun said that on the surface of the leukemia cells is a molecule receptor called CD19. Experiments showed a laboratory-grown antibody called B43 would attach directly to CD19, but to no other receptor. To make the “smart bomb,” the researchers joined the B43 antibody with the cancer-killing genistein.
The “smart bomb” was injected into 10 mice with human leukemia and their survival rates were compared with 110 untreated mice with leukemia.
All the untreated mice died within 61 days; all the mice treated with the “smart bomb” lived for more than 120 days. Later studies on the treated mice showed that 99.999% of the leukemia cells were killed.
