Phenotypic analysis of tumor cells by flow cytometry is essential for various hematological malignancies. Surface antigen analysis of multiple myeloma cells is also widely used in clinical practice. However, the heterogeneity of surface molecule expression for malignant plasma cells often makes it difficult for hematologists and physicians to interpret the data. In this review, we focus on: 1) surface molecules for detection of myeloma cells; 2) surface molecules targeted by antibody-based therapy; and 3) surface molecules possibly expressed on myeloma-initiating cells. Understanding the significance and heterogeneity of surface molecule expression in multiple myeloma cells could lead to a better understanding of myeloma biology and myeloma treatment strategies.
Bortezomib exerts a synergistic anti-myeloma effect in combination with other novel agents as well as cytotoxic drugs. In this study, we examined the efficacy and safety of the combination regimen bortezomib, cyclophosphamide, and dexamethasone (VCD) in comparison with the combination regimen bortezomib and dexamethasone (BD) in Japanese patients with multiple myeloma (MM). Twenty-two newly diagnosed MM patients treated with three cycles of either BD (n = 10) or VCD (n = 12) were enrolled in this study. We found no significant difference in cumulative dose (p = 0.29) for bortezomib between the two groups, indicating that the addition of cyclophosphamide did not require reduction of bortezomib dosage. There was no significant difference in overall response rate (90% vs 83%, respectively; p = 0.57) as well as very good partial response or better response rate (40% vs 17%, respectively; p = 0.23) after treatment between the BD and VCD groups. Grade 3–4 neutropenia as well as peripheral neuropathy was comparable between the two groups (p = 0.29 and 0.19, respectively). Thus, the addition of cyclophosphamide did not exacerbate adverse events. Modification of the regimen may be necessary for further validation of the efficacy of VCD.