Sequence of novel agents in multiple myeloma: An instrumental variable analysis

Lenalidomide and bortezomib have not been compared prospectively and are currently used in sequence for patients with multiple myeloma; however, it is unknown whether a sequence of administration could result in improved outcomes. We retrospectively reviewed electronic records of patients with multiple myeloma who had used both agents in sequence at our institution: 97 patients had lenalidomide first and 111 had bortezomib first. On multivariable analysis, the sequence of therapy was not associated with outcome. These findings were confirmed with instrumental variable analyses. Finally, use of bortezomib first was associated with improved survival for patients with baseline renal insufficiency.