Early response-based intensification of primary therapy in newly diagnosed multiple myeloma patients who are eligible for autologous stem cell transplantation: phase II study.

This phase II study prospectively evaluated the efficacy and tolerability of an early change in induction therapy before autologous stem cell transplantation (ASCT) in multiple myeloma (MM) patients who failed to achieve more than a partial response (PR) after two cycles of a cyclophosphamide, thalidomide, and dexamethasone (CTD) regimen. Patients aged 18-65 years received two cycles of CTD therapy, and then the patients who achieved more than a PR received two additional cycles of CTD therapy, while those who failed to achieve more than a PR were given intensified therapy with four cycles of a Vel-CD regimen (bortezomib, cyclophosphamide, and dexamethasone). After completing primary chemotherapy, the patients underwent ASCT. This study initially enrolled 64 patients, although four were excluded. Of the patients, 60 were treated with CTD regimen and 8 patients also had the intensified Vel-CD regimen, of whom five showing improved responses. The overall response rate before ASCT in 59 patients was 94.9 %, including 27.1 % with a stringent complete response/complete response, 23.7 % with a very good partial response (VGPR), and 44.1 % with a PR. The median time to progression (TTP) was 33.2 months (95 % CI, 26.6-34.8). Patients who attained a VGPR or better after ASCT tended to have a longer TTP than the patients who did not (not reached vs. 24.2 months, P = 0.04). In conclusion, early response-adapted intensification with a Vel-CD regimen was a well-tolerated, effective strategy for improving the response before ASCT in patients with newly diagnosed MM.