In a new study, ninety percent of young people with SCD who received blood-forming stem cells from a parent were alive and healthy one year later, free of symptoms and complications.

They did not need to take immune-suppressive medications, and in some instances their cognitive processing speed — that is, how quickly they were able to learn, think, and communicate — in some instances improved. With a median follow-up of over three years, there have been no recurrences of sickle cell pain crises, no patients have required blood transfusions, and no new patients have developed graft-versus-host disease (GVHD), a complication in which transplanted cells attack healthy tissues and organs, said lead study author Mitchell Cairo, MD, of New York Medical College in Valhalla, NY.

“These individuals have a completely new lease on life,” Dr. Cairo said. “They’re either stable or better in every organ system. What’s more, this could mean that every person with SCD who has a living parent could have a potential donor in their family.”

Currently, the only cure for SCD is a stem cell transplant using cells donated by a brother or sister who has the same tissue type, has the same mother and father, and is SCD-free. According to Cairo, only about one in six patients with SCD has a suitable sibling donor.

This study focused on a newer, modified form of stem cell transplant in which the donor’s bone marrow needs to be only 50 percent the same as the recipient’s. In this type of transplant, known as a haploidentical transplant, the patient’s mother or father can be the stem cell donor. In previous studies of haploidentical transplants for SCD, however, the rate of transplant failure has been high.

Cairo and his team sought to reduce both the rate of transplant failure and the risk of serious post-transplant complications by enriching stem cells with a type of protein called CD34 that is understood to be important in promoting the acceptance of transplanted blood-forming cells. In addition, they added back the patients’ T cells (after the transplant). T cells are a type of immune cell that has also been shown to promote the acceptance of transplanted blood-forming cells while not increasing rates of GVHD. 

In this study, 19 patients age 3-20 with frequent or severe SCD symptoms received transplanted stem cells; 15 patients received cells from their mothers, and four from their fathers. 

Engraftment, wherein the transplant recipient’s body accepts the new stem cells and the stem cells begin to produce new blood and immune cells, is one of the first steps in a successful stem cell transplant, and it occurred in all 19 patients in the study.

Chimerism is a measure of the durability of engraftment. Full donor chimerism means that 100 percent of the cells in the patient’s bone marrow and blood have developed from the donor’s stem cells. Mixed chimerism means that some of the transplant recipient’s own cells are also present in the bone marrow and blood. At one year following the transplant, the rate of chimerism was 97 percent. One patient developed acute GVHD within 100 days of the transplant and another developed chronic GVHD more than 100 days after the transplant.

Follow-up tests performed two years after the transplant showed that patients had stable or improved heart and lung function. Imaging tests showed no evidence of strokes or inflammation of blood vessels in the brain, two potentially serious complications of SCD. Tests of memory, language, intellectual functioning, and ability to plan, focus on tasks, and manage emotions all showed stability or improvement.

These results suggest that nearly 90 percent of patients (17 of 19) with SCD will go on to lead normal lives after undergoing a stem cell transplant that incorporates the techniques researchers used in this study, Dr. Cairo said. He cautioned, however, that the procedure is not successful in all patients, adding that whether patients will develop late adverse effects is not yet known. Dr. Cairo and his team have received funding to continue to follow this group of patients for another three years to assess the risk of long-term complications. 

This study was supported by the U.S. Food and Drug Administration.

This article is a press release of a study presented at the 60th American Society of Hematology (ASH) Annual Meeting and Exposition, 2018. Read the original here.