Early Human Leukocyte Antigen (HLA) Matched Sibling Hematopoietic Stem Cell Transplantation

Alemtuzumab will be administered by either subcutaneous (SQ) injection or IV. A test dose of alemtuzumab, 3 mg, is administered on the first day. If the test dose is tolerated, administration of three treatment doses will begin within 24 hours. The three treatment doses will be administered on consecutive days. On the first day, 10 mg/m2 will be given, 15 mg/m\^2 the second and 20 mg/m\^2 the third. Alemtuzumab will be started between Days -22 and -20, but all doses (test dose and three treatment doses) should be completed by Day -18.

Fludarabine will be administered at 30 mg/m\^2 IV daily for five days (Days -7 to -3).

Melphalan will be administered at 140 mg/m\^2 IV on Day -3 following fludarabine administration.