Phase II Trial Using Low Dose IL-2 to Induce Regulatory T Cells in Patients After Allogeneic Hematopoietic Stem Cell Transplantation as Graft Versus Host Disease Prophylaxis

Patients are being asked to participate in this study because treatment for their disease requires a stem cell transplant (SCT). Stem cells are the source of normal blood cells found in the bone marrow and lead to recovery of blood counts after bone marrow transplantation. With stem cell transplants, regardless of whether the donor is a full match to the patient or not, there is a risk of developing graft-versus-host disease (GVHD).

GVHD is a serious and sometimes fatal side effect of SCT. GVHD occurs when the new donor stem cells (graft) recognizes that the body tissues of the patient (host) are different from those of the donor. When this happens, cells in the graft may attack the host organs. How much this happens and how severe the GVHD is depends on many things, including how different the donors cells are, the strength of the drugs given in preparation for the transplant, the quality of transplanted cells and the age of the person receiving the transplant.

Typically, acute GVHD occurs in the first 100 days following transplant, while chronic GVHD occurs after day 100. Acute GVHD most often involves the skin, where it can cause anywhere from a mild rash to complete removal of skin; liver, where it can anywhere from a rise in liver function tests to liver failure; and the gut, where it can cause anywhere from mild diarrhea to profuse, life-threatening diarrhea. Most patients who develop GVHD experience a mild to moderate form, but some patients develop the severe, life-threatening form.

Previous studies have shown that patients who receive SCT's can have a lower number of special T cells in their blood, called regulatory T cells, than people who have not received stem cell transplants. When regulatory T cells are low, there appears to be an increased rate of severe, acute GVHD. A drug known as IL-2 (Proleukin) has been shown to increase the number of regulatory T cells in patients following stem cell transplant, and in this study investigators plan to give low dose IL-2 after transplant.

This study is called a phase II study because its major purpose is to find out whether using a low-dose of IL-2 will be effective in preventing acute GVHD. Other important purposes are to find out if this treatment helps the patient's immune system recover regulatory T cells faster after the transplant. This study will assess the safety and toxicity of low-dose IL-2 given to patients after transplantation and determine whether this drug is helpful in preventing GVHD.