If you are found to be eligible to take part in this study, based on when you join the study you will be enrolled in the Phase I or Phase II portion. If you are in Phase I, you will be assigned to a dose level of Siltuximab based on when you join this study. Up to 2 dose levels of Siltuximab will be tested. Three (3) to 6 participants will be enrolled at each dose level. The first group of participants will receive the highest dose level. If intolerable side effects are seen in the first group, the next group will receive a lower dose.