Analysis of monoclonal protein production and response for patients with atypical serum immunofixation patterns (ASIPs). The distribution of M-protein for patients at the initiation of lenalidomide and dexamethasone with clarithromycin (BiRD) therapy (A), and the relative distribution of M-proteins as witnessed on ASIPs (B) are shown. The maximum response rates achieved with BiRD therapy are compared in patients who developed ASIPs (C), those who did not develop ASIPs (D), and to the entire cohort of BiRD-treated patients on study (E). CR, complete response; PR, partial response; sCR, stringent CR; SD, stable disease; and VGPR, very good PR.