The impact of upfront versus sequential use of bortezomib among patients with newly diagnosed multiple myeloma (MM): a joint analysis of the Singapore MM Study Group and the Korean MM Working Party for the Asian myeloma network.

From the comprehensive MM registries of the Singapore (SG) and South Korea (SK) MM study groups, we study the survival data of 432 unselected and previously untreated MM patients diagnosed from 2006 to 2009. Although novel agents were introduced to both countries which have compatible healthcare standards at the same time, MM patients with high-risk features in SG could receive frontline bortezomib while bortezomib could only be approved for salvage setting in SK. After a median follow-up of 19 months, despite 26% of patients in SG versus none in SK having received frontline bortezomib, the overall bortezomib-exposure rate was higher in SK (60% versus 47%, p<0.001). Significantly more patients had no response to induction in SK. Although the median overall survival (OS) of patients in SG and SK was not significantly different (not reached versus 4.83 years respectively, p=0.2), corresponding 2-year OS for high-risk ISS patients treated in SG and SK was 81% and 67% respectively (p=0.01). On multivariate analysis stratified by country, the attainment of ≥ VGPR was the only significant prognostic factor in SG while the presence of high-risk ISS has significant early prognostic impact in SK. Frontline use of bortezomib compared to its sequential may avert early mortality especially among patients with high-risk MM.