Ruxolitinib Prior to Transplant in Patients With Myelofibrosis

The purpose of this study is to find out if giving the study drug Ruxolitinib (INC424) prior to a combination of other chemotherapeutic drugs (Fludarabine and Busulfan) before infusing another person's hematopoietic stem cells (bone marrow transplantation) will be successful in people who have advanced primary myelofibrosis (PMF), post-polycythemia vera myelofibrosis (PPV-MF) or post-essential thrombocythemia myelofibrosis (PET-MF), collectively known as myelofibrosis (MF). MF is a disorder in which bone marrow tissue develops in abnormal sites because the bone marrow itself undergoes fibrosis or scarring. This study plans to evaluate whether adding the drug Ruxolitinib will further aid in reducing pre-transplant spleen size, improve physical performance levels and reduce adverse events (side effects) related to the transplant. Ruxolitinib is a drug that is approved by the FDA for the treatment of patients with advanced forms of myelofibrosis. Using Ruxolitinib prior to stem cell transplantation is experimental.