Durvalumab in Treating Patients With Primary, Post-Polycythemia Vera, or Post-Essential Thrombocythemia Myelofibrosis

The main purpose of this investigational research study is to determine how safe and tolerable the study drug, MEDI4736 (Durvalumab), is in patients with myelofibrosis (MF). The study drug belongs to a group of drugs called immune checkpoint inhibitors, which have shown promise in other forms of cancer, such as melanoma and lung cancer. One of the effects that this drug has is to activate the patient's own natural immune system. The purpose of this study is to examine the safety and tolerability of the study drug, to study how effective it is at treating patients with myelofibrosis, and to explore how certain markers in the patient's blood and/or bone marrow may be affected by the study drug.