Rapid early monoclonal protein reduction after therapy with bortezomib or bortezomib and pegylated liposomal doxorubicin in relapsed/refractory myeloma is associated with a longer time to progression

Abstract

BACKGROUND: A rapid and early monoclonal (M) protein response during initial therapy in patients with multiple myeloma had been identified as a predictor of superior long-term outcome in some-but not all-studies. METHODS: To determine if the parameter of M protein reduction was of value in the relapsed and/or refractory setting, retrospective landmark analyses were performed at the end of cycles 2 and 4 of a phase 3 study, which randomized such patients to receive bortezomib alone or pegylated liposomal doxorubicin (PLD) with bortezomib. RESULTS: Compared with a <25% reduction in M protein at the landmark time point, patients with a 50% to <75% reduction after cycle 2 had a significantly lower hazard ratio (HR) for time to progression (HR = 0.41; 95% confidence interval [CI], 0.26-0.64; P