How do you approach management of a patient with persistent EBV infection and MAS despite treatment with Rituximab, anakinra and canakinumab? 

The (presumed) rationale for B cell depletion in EBV-associated MAS is to deplete infected B cells that are potential targets for cytotoxic T/NK cells that may have perforin pathway defects leading to excessive/prolonged cytokine release. Failure of the MAS to resolve with steroids/anakinra/rituxima...