Survival Impact of Response with Bortezomib Induction on Myeloma Patients Receiving Autologous Stem Cell Transplantation.

Abstract 4590

Autologous stem cell transplantation (ASCT) is the standard of care for patients with multiple myeloma (MM) aged less than 65 years. Before the era of novel agents the absence of initial response to induction therapy had no impact on outcome after ASCT. With the introduction of novel agents response rate with initial therapy are now between 70% and 100%. This study analyzes the association of progression-free survival (PFS) and overall survival (OS) after ASCT with the response to induction therapy with a regimen that contains bortezomib for patients with MM.

We performed a retrospective analysis of 61 patients with MM who consecutively received bortezomib-containing regimens from 2 institutes before collection of peripheral blood stem cells and ASCT. The median age was 54 (34-65) years and 41 (67.2%) were male. Eight (16.4%) patients received bortezomib as a first-line therapy whereas the others as the second line or more. Melphalan alone was used for conditioning and 29 (47.5%) received thalidomide maintenance therapy.

Fifty four of 61 patients (88.5%) achieved objective response after bortezomib induction treatment. Post-bortezomib complete response (CR), very good partial response (VGPR) and partial response (PR) were present in 33 (54.1%), 6 (9.8%) and 15 (24.6%), respectively. After ASCT CR, VGPR and PR were 41 (67.2%), 3 (4.9%) and 6 (9.8%), respectively. Achieving CR, VGPR or PR after bortezomib therapy failed to show an improvement in PFS and OS after ASCT. In contrast, post-transplant responses markedly influenced the outcomes after ASCT; patients achieving either CR or ≥VGPR had significantly longer PFS (P=.001 and .035, respectively) and OS (P=.002 and .002, respectively) compared to those without CR or ≥VGPR. Post-transplant maintenance treatment was not associated with improved PFS and OS in this cohort.

Our data suggest that the response to bortezomib induction therapy could not predict outcome after ASCT. Achieving post-transplant CR or ≥VGPR is critical for prolongation of PFS and OS.