Adults stop anti-rejection drugs after partial stem-cell transplant reverses sickle cell disease

NIH trial success suggests a new treatment option for older, sicker patients

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2014-07-02

Half of patients in a trial have safely stopped immunosuppressant medication following a modified blood stem-cell transplant for severe sickle cell disease, according to a study. The trial was conducted at the National Institutes of Health’s Clinical Center in Bethesda, Maryland, by researchers from NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the National Heart, Lung, and Blood Institute.

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Blood drawn from a sickle cell patient.

In sickle cell disease (SCD) sickle-shaped cells block blood flow. It can cause severe pain, organ damage and stroke. The only cure is a blood stem-cell, or bone marrow, transplant. The partial transplant performed in the study is much less toxic than the standard “full” transplant, which uses high doses of chemotherapy to kill all of the patient’s marrow before replacing it with donor marrow. Several patients in the study had less than half of their marrow replaced.

Immunosuppressant medication reduces immune system strength and can cause serious side effects such as infection and joint swelling. In this study, 15 of 30 adults stopped taking the medication under careful supervision one year after transplant and still had not experienced rejection or graft-versus-host disease at a median follow up of 3.4 years.

Side effects caused by immunosuppressants can endanger patients already weakened by years of organ damage from sickle cell disease,” said expert. “Not having to permanently rely on this medication, along with use of the relatively less-toxic partial stem-cell transplant, means that even older patients and those with severe sickle cell disease may be able to reverse their condition.”

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Blood drawn from a sickle cell patient after stem-cell transplant.

One of the most debilitating effects of sickle cell disease is the often relentless pain,” added expert. “Following the transplant, we saw a significant decrease in hospitalizations and narcotics to control that pain.”

The partial transplant used donor stem-cells from healthy siblings. It effectively reversed SCD in 26 of 30 patients and allowed them to achieve stable mixed donor chimerism, a condition in which a person has two genetically distinct cell types in the blood. The study includes patients from an NIH study reported in 2009, in which partial stem-cell transplants reversed SCD in 9 of 10 people.

In the United States, more than 90,000 people have SCD , a genetic disorder found mainly in people of African ancestry. Worldwide, millions of people have the disease.

“The devastating complications associated with sickle cell disease can deeply affect quality of life, ability to work and long-term well-being,” said expert. “This study represents an important advance in our efforts to make a potentially transformative treatment available to a wider range of people, especially those who could not tolerate a standard stem-cell transplant or long-term use of immunosuppressants.”

Source: U.S. National Institutes of Health