Role of autologous stem cell transplant after induction therapy with bortezomib-lenolidomide or bortezomib-thalidomide in newly diagnosed multiple myeloma patients

8596 Background: The introduction of novel therapeutic options with bortezomib and immunomodulatory agents in the up-front management of multiple myeloma (MM) has significantly improved induction response rates. However, the role of high dose chemotherapy and autologous stem cell transplant (ASCT) after induction with these highly active agents is not known, especially in patients with only a partial response to induction therapy. Methods: We conducted a retrospective review of 95 newly diagnosed MM patients treated with induction bortezomib-lenolidomide-dexamethasone (BLD) or bortezomib-thalidomide-dexamethasone (BTD) prior to ASCT. Responses were graded according to IMWG criteria. Results: 19 patients received BLD and 76 patients received BTD. All patients were conditioned with a melphalan-based regimen. Of the 19 patients who underwent induction with BLD, complete response (CR), very good partial response (VGPR) and partial response (PR) were achieved in 2 (11%), 8 (42%) and 9 (47%) respectively for an overall response rate (ORR) of 19/19 (100%). After ASCT, CR, VGPR and PR were achieved in 9 (47%), 5 (26%) and 5 (26%) respectively for a continued ORR of 21/21 (100%). Notably, 4/8 (50%) of patients with a VGPR after induction therapy with BLD improved to a CR after ASCT. 3/9 (33%) of patients with an initial PR to BLD improved to a CR and 1/9 (11%) with a PR improved to VGPR after ASCT. Of the 76 patients who underwent induction with BTD, CR, VGPR and PR were achieved in 6 (8%), 37 (49%) and 31(41%) respectively for an ORR of 74/76 (97%). 1 patient had stable disease and 1 patient had progressive disease. After ASCT, 27/76 (36%) achieved a CR, 30/76 (39%) a VGPR and 18/76 (24%) a PR for an ORR of 75/76 (99%). Of the patients who initially had a VGPR to BTD 16/37 (43%) improved to a CR while 5/32(16%)of PR patients improved to a CR and 9/32 (28%) of PR patients improved to a VGPR. Conclusions: Of the 40 patients who only achieved a PR after induction therapy with BLD or BTD, 16 (40%) had further improvement to a CR or VGPR after ASCT. Thus there is a significant benefit of ASCT in these patients who initially demonstrate relative resistance to induction therapy with highly active regimens. [Table: see text]