 You will receive the drugs tacrolimus and methotrexate to help lower the risk of a reaction called graft-vs.-host disease GVHD. GVHD is when the donated immune cells in the transplant react against the body of the person receiving the cells. Tacrolimus will be given by IV for about 2 weeks, and after that it is given by mouth as a pill for at least 3 months. Methotrexate will be given as an IV injection for 3 to 4 doses over the first 11 days after the stem cell transplant. 