Scientists already had achieved this in mice; Stanford researchers now have extended it to people. Their study is published in Thursday's New England Journal of Medicine and was funded by the National Institutes of Health.
Specialists said the study was small and preliminary, but very promising.
"If it works, we would be able to do transplants in a lot more people," said Dr. Mary Horowitz, scientific director of the Center for International Blood and Marrow Transplant Research, based at the Medical College of Wisconsin, which had no role in the research.
Ideally, a leukemia or lymphoma patient would be given radiation or high doses of chemotherapy to destroy the cancerous bone marrow before receiving healthy marrow or blood stem cells from a donor. However, many patients, especially those over 50, die of infections they are unable to fight off before the new marrow takes hold and grows.
To avoid this problem, doctors usually destroy only part of the patient's original marrow. That brings other dilemmas: some cancerous blood cells remain, and the new marrow frequently attacks the old — an often-fatal problem called graft-versus-host disease.
Stanford researchers developed a way to condition the recipient to accept the new marrow and to inactivate the parts of the patient's immune system that would attack it. They used a combination of low-dose radiation over two weeks and short courses of immune-suppressing drugs.
Only 2 of the 37 patients given the experimental treatment developed severe graft-versus-host disease. Ordinarily, more than half of them would have.