Special molecules, armed with cell-killing chemicals and designed to home in on tumors, are showing real promise toward treatment of human breast, colon and lung cancer, scientists reported yesterday.
The experimental treatment can be likened to military use of stealth bombers to attack specific targets, with little damage to buildings nearby.
"We are excited about the pre-clinical data," because many complete cures have been achieved in laboratory animals, said immunologist Pamela Trail, who collaborated on the research.
Dr. Alan Houghton, chief of clinical immunology at Memorial Sloan-Kettering Cancer Center in New York, said that "the most exciting part" is that the treatment works on established tumors in animals. "It's the first indication of real effects" on such tumors, he said.
The real test will come, however, when it is tried in cancer patients.
The treatment uses highly modified antibodies to carry an existing anti-cancer drug, Doxorubicin, directly to the cancer cells. The antibodies dump the chemical inside cancer cells, and when enough Doxorubicin gets inside, the cancer cells die.
The results were reported in the current edition of Science magazine.
Ms. Trail, who works at the Bristol-Myers Squibb Pharmaceutical Research Institute in Princeton, N.J., said, "We were able to demonstrate cures of established human tumors grafted into rats and mice." In some of the rat experiments, for example, "we got 94 percent" cures, "and that's not a bad number."
She said the work was done in collaboration with the company's researchers in Wallingford, Conn., and in Seattle.
One potential problem, the researchers said, is that the antibody being used can also home in on a few normal cells of the gastrointestinal tract, but generally in small numbers. In the rats, this "cross-reactivity" did not seem to cause problems.
"But the real proof will come," Ms. Trail said, when the new treatment is tested in humans.