July 3, 2014 | by Nicole White
Adults with sickle cell disease soon may have a new treatment option: bone marrow transplants.
Children with sickle cell disease have been treated successfully with transplantation of bone marrow, more officially known as hematopoietic stem cells, from other people. But the procedure has been less successful in adults, because the high-dose chemotherapy or radiation necessary to kill their own cells and allow the new cells to engraft has often been too toxic for adults to tolerate. A lower-density transplantation, however, might be the breakthrough that such patients have needed.
A new study has shown promising results for patients with severe sickle cell disease – including adults – who received a mix of a sibling's cells and their own cells. The study, published July 2 in the Journal of the American Medical Association, found that adults receiving the lower-density transplant were able to avoid long-term mega-doses of chemotherapy or radiation.
Sickle cell disease is a group of diseases that affect hemoglobin, the molecule in red blood cells that delivers oxygen to cells in the body. In patients with the disease, those molecules tend to be shaped like sickles, or crescents.
The disease usually causes a low number of red blood cells, repeated infections and periodic episodes of pain. The painful episodes occur when the sickle-shaped cells get stuck in small blood vessels. In addition to causing pain, the episodes can deprive organs and tissue of oxygen-rich blood, leading to permanent damage. The lungs, kidneys, spleen and brain are especially vulnerable.
“These results are incredibly exciting, as adults with sickle cell disease suffer from major medical complications and their life expectancy is significantly shortened,” said Julie Wolfson, M.D., M.S.H.S., a pediatric oncologist at City of Hope who is leading a study on bone marrow transplants for sickle cell disease. “By putting a potentially curative treatment on the table for even the sicker, older patients, we are getting to a place where we can truly rethink options for therapy in sickle cell disease across the spectrum.”
The study is good news, she says, for ongoing clinical trials at City of Hope that are similar but unrelated. City of Hope is part of a multicenter trial exploring a reduced intensity conditioning regiment for patients ages 16 to 40 who need transplantation for sickle cell disease. The first wave of patients received donors from siblings, and the current trial will make unrelated donors who are a match an option.
“The big picture on sickle cell disease is that the life expectancy for these patients is in their 40s, and there are significant multiorgan complications in addition to the more well-recognized pain crises," Wolfson said.
The JAMA study included 30 adults with severe sickle cell disease, all of whom received a simplified hematopoietic stem cell transplantation regimen, using cells donated from matched siblings. The treatment had few toxic effects, but all patients continued taking immunosuppression medications. Selected patients were given the option to stop immunosupression medications after one year.
Of the group, 29 patients were still alive and 26 patients – 87 percent – had long-term stable donor engraftment without acute or chronic graft-versus-host disease. Fifteen of the patients successfully stopped immunosuppression medication and had no graft-versus-host disease. The study shows promise for adults with severe sickle cell disease, and who have had few options for treatment.
Learn more about clinical trials at City of Hope.
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