Santosh Saraf and his colleagues at the University of Illinois have used a low-dose irradiation/alemtuzumab plus stem cell transplant procedure to cure patients of sickle-cell disease. 12 adult patients have been cured of sickle-cell disease by means of a stem cell transplantation from a healthy, tissue-matched donor.
This new procedure obviates the need for chemotherapy to prepare the patient to receive transplanted cells and offers the possibility of curing tens of thousands of adults from sickle-cell disease.
Sickle cell disease is an inherited disease that primarily affects African-Americans born in the United States. The genetic lesion occurs in the beta-globin gene that causes hemoglobin molecules to assemble into filaments under low-oxygen conditions. These hemoglobin filaments deform red blood cells and cause them to plug small capillaries in tissues, causing severe pain, strokes and even death.
Fortunately, a bone marrow transplant from a healthy donor can cure sickle-cell disease, but few adults undergo such a procedure because the chemotherapeutic agents that are given to destroy the patient’s bone marrow leaves from susceptible to diseases, unable to make their own blood cells, and very weak and sick.
Fortunately, a gentler procedure that only partially ablate the patient’s bone marrow was developed at the National Institutes of Health ()NIH) in Bethesda, Maryland. Transplant physicians there have treated 30 patients, with an 87% success rate.
In the Phase I/II clinical trial at the University of Illinois, 92% of the patients treated with this gentler procedure that was developed at the NIH.
Approximately 90% of the 450 patients who received stem cells transplants for sickle-cell disease have been children. However, chemotherapy has been considered too risky for adult patients who are often weakened far more than children by it.
Adult sickle-cell patients live an average of 50 years with a combinations of blood transfusions and pain medicines to manage the pain crisis. However, their quality of life can be quite low. Now, with this chemotherapy-free procedure, adults with sickle-cell disease can be cured of their disease within one month of their transplant. They can even go back to work or school and operate in a pain-free fashion.
In the new procedure, patients receive immunosuppressive drugs just before the transplant, with a very low dose of whole body radiation. Alemtuzumab (Campath, Lemtrada) is a monoclonal antibody that binds to the CD52 glycoprotein on the surfaces of lymphocytes and elicits their destruction, but not the hematopoietic stem cells that gives rise to them. Next, donor cells from a healthy a tissue-matched sibling or donor are transfused into the patient. Stem cells from the donor home to the bone marrow and produce healthy, new blood cells in large quantities. Patients must continue to take immunosuppressive drugs for at least a year.
In the University of Illinois trial, 13 patients between the ages of 17-40 were given transplants from the blood of a healthy, tissue-matched sibling. Donors must be tested for human leukocyte antigen (HLA) markers on the surfaces of cells. Ten different HLA markers must match between the donor and the recipient for the transplant to have the best chance of evading rejection. Physicians have transplanted two patients with good HLA matches, to their donor, but had a different blood type than the donor. In many cases, the sickle cells cannot be found in the blood after the transplant.
In all 13 patients, the transplanted cells successfully engrafted into the bone marrow of the patients, but one patient failed to follow the post-transplant therapy regimen and reverted to the original sickle-cell condition.
One year after the transplantation, the 12 successfully transplanted patients had normal hemoglobin concentrations in their blood and better cardiopulmonary function. They also reported significantly less pain and improved health and vitality,
For of the patients were able to stop post-transplantation immunotherapy, without transplant rejection or other complications.
“Adults with sickle-cell disease can be cured with chemotherapy – the main barrier that has stood in the way for so long,” said Damiano Rondelli, Professor of Medicine and Director of the Stem Cell Transplantation Program at the University of Illinois. “Our data provide more support that this therapy is safe and effective and prevents patients from living shortened lives, condemned to pain and progressive complications.”
These data were published in the journal Biology of Blood and Marrow Transplantation, 2015; DOI 10.1016/j.bbmt.2015.08.036.