Complete response correlates with long-term survival and progression-free survival in high-dose therapy in multiple myeloma.

There are a number of reports in literature data on the long-term outcomes of patients with multiple myeloma treated with high-dose therapy and autologous stem cell transplantation (HDT/SCT). While in general these data support the association between maximal tumor response and overall survival or progression-free survival after HDT/SCT, some trials have failed to find such correlation and there is no recent comprehensive literature analysis of this issue. We, therefore, performed a comprehensive literature review to identify prospective and retrospective studies on HDT/SCT in frontline multiple myeloma in which long-term outcomes were reported according to best tumor response observed. Following a prospectively defined search strategy we identified 21 studies (10 prospective and 11 retrospective studies) in which outcomes of 4,990 HDT/SCT patients according to their best tumor response were reported. The majority of these studies indicated a correlation between maximal response during or after HDT/SCT and long-term outcomes (overall survival and event-free/progression-free survival). The conclusions in individual studies report on the association between maximal response following induction therapy and long-term outcomes were more heterogeneous, possibly due to the low rate of complete response after standard induction therapy in each individual study. We, therefore, performed two types of meta-analyses, one based on the p-values reported for these associations in the individual studies, and one based on the primary response and outcome data provided in the individual studies. Both meta-analyses indicated highly significant associations between maximal response (complete response/near complete response/very good partial response) during or after HDT/SCT and long-term outcomes (overall survival and event-free/progression-free survival). Both meta-analyses also provided evidence of highly significant associations between maximal response following induction therapy and long-term outcomes (overall survival and event-free/progression-free survival).