Absence of spontaneous response improvement beyond day+100 after autologous stem cell transplantation in multiple myeloma

Resumen:
The response evaluation after autologous stem-cell transplantation (ASCT) is usually performed at day + 100 in patients with multiple myeloma (MM). A recent report suggests that improvement in the response can be observed beyond day + 100. The aim of the present study has been to evaluate the rate of improved response and outcome beyond day + 100 after ASCT, with and without maintenance therapy. One hundred and forty-four patients who underwent single ASCT with chemosensitive disease and achieved less than CR at day 100 post ASCT were evaluated. Seventy-four patients (51.4%) did not receive any maintenance with only one of them showing an upgrade in the response. The remaining 70 patients (48.6%) received maintenance therapy; eleven of them (15.7%) improved their response beyond day + 100. The outcome of these patients was better than those who did not upgrade their response in both progression-free survival and overall survival (P = 0.019 and P = 0.031, respectively). In conclusion, the improvement in response beyond day + 100 after ASCT in patients not receiving any therapy is exceedingly rare. A minority of patients receiving maintenance therapy after ASCT upgrades their response and this finding is associated with better outcome.