Bortezomib is superior to high-dose dexamethasone for the treatment of patients with multiple myeloma who have had a relapse after one to three previous therapies.

Purpose The clinical outcome of multiple myeloma (MM) is heterogeneous. A simple and reliable tool is needed to stratify MM patients. We combined the International Staging System (ISS) with chromosomal abnormalities (CA) detected by interphase Fluorescence In Situ Hybridization (iFISH) after CD138 plasma cells purification and serum lactate dehydrogenase (LDH) to evaluate their prognostic value in newly diagnosed MM (NDMM). Methods Clinical and laboratory data from 4445 NDMM patients enrolled in eleven international trials were pooled together. The K-adaptive partitioning algorithm was used to define the most appropriate subgroups with homogeneous survival. Results ISS, CA, and LDH data were simultaneously available in 3060/4445 patients. We defined three groups: revised ISS (R-ISS) I (N=871), including ISS I (serum β2-microglobulin level <3.5mg/L and serum albumin level ≥3.5g/dL), no high-risk CA [del(17p) and/or t(4;14) and/or t(14;16)] and normal LDH level (below the upper limit of normal range); R-ISS III (N=295), including ISS III (serum β2-microglobulin level >5.5mg/L) and high-risk CA or high LDH level; R-ISS II (N=1894), including all the other possible combinations. At a median follow-up of 46 months, the 5-year OS was 82% in the R-ISS I, 62% in the R-ISS II, and 40% in the R-ISS III groups; the 5-year PFS was 55%, 36% and 24%, respectively. Conclusions The R-ISS is a simple and powerful prognostic staging system and we recommend its use in future clinical studies to stratify NDMM patients effectively with respect to the relative risk to their survival.

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