The treatment of multiple myeloma (MM) with proteasome inhibitor (PI) bortezomib has significantly improved the survival of patients with MM. The 26S proteasome inhibitor targets the unfolded protein response (UPR) by inhibiting proteasome degradation of ubiquitinated paraprotein, subsequently leading to the lethal accumulation of paraprotein within the endoplasmic reticulum. According to secretory status of monoclonal immunoglobulin, newly diagnosed MM (NDMM) is divided into measurable and unmeasurable disease, which includes oligosecretory, nonsecretory, and nonproducer myeloma. The present study analyzed the clinical characteristics of 822 patients with NDMM who had either measurable or unmeasurable diseases and received bortezomib- or thalidomide-based therapies. Our results showed that the median progression-free survival (PFS) and overall survival (OS) of patients with MM was significantly longer in patients with measurable disease than those in oligosecretory, nonsecretory, and nonproducer MM (PFS: 27, 18, 19, and 2.0 months, respectively [P < .001]; OS: 51, 30, 22, and 2.0 months, respectively [P < .001]). Within the unmeasurable group, patients with nonproducer myeloma showed the shortest PFS and OS. Importantly, compared with thalidomide treatment, bortezomib significantly improved the PFS and OS of patients with MM with measurable disease (PFS: 25 and 33 months [P = .022], respectively; OS: 41 and 58 months [P < .001], respectively), but not those with unmeasurable disease (PFS: 18 and 16 months [P = .617], respectively; OS: 22 and 27 months [P = .743], respectively). Our results indicate that bortezomib-based therapy performed no better than thalidomide-based treatment in patients with unmeasurable MM. The results need to be confirmed in other patient cohorts, preferably in the context of a prospective trial.
© 2019 by The American Society of Hematology.