In a patient with Waldenstrom's macroglobulinemia doing well and feeling better on ibrutinib & rituximab, but with a rising IgM, do you switch treatment or continue?  

A lot depends on the pace of increase of the IgM and the line of therapy. If the pace is rapid, I would think about changing therapy. If the pace of increase is small and the patient is asymptomatic, you could continue a little longer. If planning to changing therapy, it may be reasonable to restage...