Unsustained complete response of less than 24 months after autologous stem cell transplantation predicts aggressive myeloma with short survival.

Complete response (CR) predicts superior survivals in myeloma. To define the impact of duration of CR posttransplantation on survivals, 71 myeloma patients, who underwent an intended early (a staged approach) or frontline use of bortezomib-based induction, followed by autologous stem cell transplantation (ASCT) were studied. Achievement of CR was assessed every 4-weekly until maximal response after ASCT and then 6-weekly thereafter. All patients had follow-up time of ≥24 months from time of best response, of whom 27 failed to attain CR (non-CR) whereas 44 achieved CR. At 12, 18 and 24 months post-ASCT, 3 (4.2%), 6 (8.4%) and 11 (15.4%) patients lost CR, respectively, with maximal survival difference observed in the group with CR durations of ≥24 or <24 months. Patients with unsustained CR had survival inferior to those never achieving CR (p = 0.05). Unsustained CR of <24 months was associated with international staging system stage III (p = 0.007) and shorter postrelapse survival (p < 0.001). Both overall survival and event-free survival were superior in myeloma patients with CR of ≥24 months (p < 0.001). In multivariate analysis, international staging system stage I/II, CR/nCR post-ASCT and CR duration of ≥24 months remained favourable prognostic factors for both overall survival and event-free survival. In conclusion, CR of <24 months is an independent adverse risk factor for survival with a short postrelapse survival.