High immunoproteasome concentration in the plasma of patients with newly diagnosed multiple myeloma treated with bortezomib is predictive of longer OS.

Abstract Purpose Proteasome inhibitors (PI) bortezomib or carfilzomib among them, play a crucial role in the modern standard therapy for multiple myeloma (MM). In this study, we intended to evaluate whether immunoproteasome (IMP) concentration could act as an effective biomarker which determines the probability of response to treatment with bortezomib, in order to detect groups of patients who are more likely to respond to treatment with PI. Materials and methods In our study, we evaluated IMP concentration in the plasma of 40 patients with monoclonal gammopathy of undetermined significance (MGUS) and 116 patients with newly diagnosed MM during treatment with or without PI. Results The values of all the studied parameters after the applied chemotherapy in the responders’ group of patients declined considerably during the consecutive cycles of chemotherapy compared to their initial levels. On the contrary, in the group of non-responders, we observed no change in the measured IMP parameters during the consecutive cycles of therapy. We also showed that higher baseline IMP concentration might indicate longer overall survival (OS) in all patients. Conclusions Our results indicate that assessing plasma IMP concentration can be applied as a strong biomarker for predicting clinical response to treatment and OS in patients with newly diagnosed MM.