Study represents new use of bone marrow transplantation

Researchers at Fred Hutchinson Cancer Research Center have opened a clinical trial to test the theory that giving a patient a new immune system can cure severe cases of Crohn's disease, a chronic inflammatory condition of the gastrointestinal tract.

Funded by an infrastructure grant from The Eli and Edythe Broad Foundation, the initial goal of the Crohn's Allogeneic Transplant Study (CATS) is to treat a small number of patients with treatment-resistant Crohn's disease by transplanting matched bone marrow cells from a sibling or unrelated donor. Such a bone marrow transplant replaces a diseased or abnormal immune system with a healthy one.

The idea of swapping out the immune system is based on evidence that Crohn's is related to an abnormal immune response to intestinal bacteria and a loss of immune tolerance. There is strong evidence that genetic abnormalities in the immune regulatory system are linked to the disease, according to CATS principal investigator George McDonald, M.D., a transplant researcher and gastroenterologist in the Hutchinson Center's Clinical Research Division.

Although the CATS clinical trial represents a new direction for bone marrow transplantation, the procedure has precedent. The Hutchinson Center, which pioneered bone marrow and hematopoietic cell transplantation to treat blood cancers, has used allogeneic transplants to cure patients who suffered from both leukemia and Crohn's, with subsequent disappearance of the signs and symptoms of Crohn's. Similar experiences have been reported from studies done in Germany.

While autologous stem cell transplants - in which the patient's own hematopoietic cells are removed and then returned after high-dose chemotherapy is given to suppress the immune system - have been used to treat Crohn's patients, the benefits have not always been permanent, probably because the risk genes for Crohn's are still present. "Autologous transplantation following chemotherapy beats the disease down but the Crohn's tends to come back," McDonald said.