Interim results of the trial, which began two years ago, will be presented by researchers at the annual meeting of the American Society of Hematology in Philadelphia (Dec. 9, 4 p.m., Room 204).
The study seeks to produce better outcomes for patients receiving stem cell transplants for diseases such as leukemia and lymphoma. Such patients are at risk for GVHD, a condition in which transplanted immune cells mount an attack on patients' own tissue and organs. The drugs tacrolimus and methotrexate, though offering moderate control of GVHD, are associated with side effects such as kidney failure, high blood pressure, mouth sores, liver damage, and lowered white blood cell counts.
"These are very exciting early data," says the study's lead author, Joseph Antin, MD, of Dana-Farber. "We have been looking for ways of reducing transplant-related side effects for many years and these data tell us that we are on the right track. We are proceeding with further studies designed to eliminate methotrexate entirely while continuing to reduce toxicity and control GVHD."
Because sirolimus – a medication that interferes with the signaling mechanism in immune system cells – has been shown to work "synergistically" with tacrolimus, researchers theorized that low doses of the two drugs, in combination with methotrexate, might provide more effective control of GVHD with fewer side effects.
The 41-patient study is bearing out those hopes. Whereas 30 percent of unrelated donor transplant patients would normally be expected to develop severe GVHD, only 13 percent of the patients in the study have incurred that level of GVHD. The therapy produced no unusual side effects and patients' blood counts reached adequate levels.
Dana-Farber Cancer Institute (www.danafarber.org) is a principal teaching affiliate of the Harvard Medical School and is among the leading cancer research and care centers in the United States. It is a founding member of the Dana-Farber/Harvard Cancer Center (DF/HCC), designated a comprehensive cancer center by the National Cancer Institute.