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

PRIMARY OBJECTIVES: I. To evaluate safety and tolerability of the drug siltuximab in the myelofibrosis patient population. SECONDARY OBJECTIVES: I. To determine clinical improvement (CI). II. To determine the overall response rate (ORR). TERTIARY OBJECTIVES: I. To determine if siltuximab results in improvement in iron dysregulation. II. To determine changes in inflammatory stress that may correlate with clinical response. OUTLINE: Patients receive siltuximab intravenously (IV) over 60 minutes on day 1. Patients also undergo bone marrow biopsy and aspiration at baseline and at the end of treatment (within 30 days of last siltuximab dose) or as clinically indicated. Treatment repeats every 21 days for up to 6 courses in the absence of disease progression, unacceptable toxicity, or patient decision to withdraw. Patients who are responding after 6 courses may receive additional siltuximab treatment for up to 1 year at the discretion of the study doctor. After completion of study treatment, patients are followed up at 30 days.