What is your approach for salvage therapy in a patient with Relapsed/Refractory Primary Mediastinal B-Cell Lymphoma that has received a Rituximab-containing upfront regimen?  

First, it is important to distinguish refractory from relapsed. If the patient has PET positive disease remaining in mediastinum, but TMV (tumor metabolic volume) has decreased significantly, there is sometimes a long period before PMBCL will go fully negative on a PET, especially very bulky tumors....