The tumors of about one-fourth of the study's 300 patients with non-small cell lung cancer, renal cell cancer and advanced melanoma significantly decreased in size after the patients were given the drug.
The study -- which was also authored by researchers from Johns Hopkins University, Harvard University, Bristol-Myers Squibb and other institutions -- appears Saturday in the New England Journal of Medicine. Several of the researchers are also presenting their findings at the annual meeting of the American Society of Clinical Oncology in Chicago this weekend.
The drug, known as BMS-936558, was developed by Bristol-Myers Squibb and is still in the study phase.
The drug is an antibody designed to restore the functions of lymphocyte cells, known as T-cells, and to foil tumors' ability to fight off the immune system.
"What happens is that the T-cells look for things that shouldn't be in the body," said co-author Scott Gettinger, associate professor of medicine at Yale.
But sometimes, Gettinger said, "there's a communication between the T-cell and the tumor, which tells the T-cell to not attack it." The drug, he said, "binds to the T-cell, which doesn't allow the negative communication."
Tumors shrank by at least 30 percent in 28 percent of the melanoma patients; a slightly smaller percentage of renal cancer patients had similar reductions in tumors. And 18 percent of the lung cancer patients had tumor reductions of 30 percent or more.
Gettinger said the progress made in the lung cancer tumors was most surprising.
"Immunotherapy has been tried for a long time in lung cancer in prior studies and it never amounted to much," he said.
Gettinger said the drug has to go through the U.S. Food and Drug Administration approval process so it could be years before it is widely available.