Impact of the New Anti-Myeloma Drugs on Outcome of Allogeneic Stem-Cell Transplantation with Reduced-Intensity Conditioning in Patients with High-Risk Multiple Myeloma

Abstract 4456

The increasing use of the novel agents, lenalinomide and bortezomib, in the treatment of multiple myeloma (MM) has contributed to higher complete remission (CR) rates and longer overall (OS) and event free survival (EFS). We assessed the impact of these drugs on the outcome of high-risk MM patients treated with allogeneic stem-cell transplantation (allo-SCT) after reduced-intensity conditioning (RIC) over the last 10 years in our program.

This retrospective study compared 45 patients (group1) transplanted in our centre between January 1999 and January 2006 and who had not received either novel agent prior to transplant (as induction or relapse therapy) with 34 patients (group 2) transplanted between January 2006 and June 2010 who received either one or both drugs before allo-SCT.

The median time between diagnosis and Allo-SCT was 37 months (6–161) and 41 months (9–145) in the two groups respectively (p=NS). The median time between auto-SCT and allo-SCT was 9 months (2–89) and 27 months (2–49) respectively (p<0.0001). 36 patients (80%) in the first group vs. 8 patients (24%) in the second group received a tandem auto allo-SCT (p<0.0001). The disease status at transplantation was in CR in 2 patients (4%) vs. 10 patients (29%) and PR or stable disease in 35 patients (78%) vs. 21 patients (62%) in the first and the second group respectively (p<0.0033). in the table 1 we resumed some important data. Table 1 

Groups differ in several aspects: In recent years allogeneic transplant was considered rather as salvage therapy in patients relapsing after auto-SCT than in a tandem auto-allo strategy, patients with cytogenetic aberrations (p<0.005), and stem cell source from unrelated donor (13 patients (38%) vs. none) (p<0.0004), and two days of anti-thymoglobuline (ATG 2,5mg/kg/day). (P<0.001), in the second group. Table 1 

The median follow-up after transplant was 45 (2–127) and 16 (3–39) months in the first and second group respectively (p<0.001). The cumulative incidence of acute graft versus-host disease (GVHD) tended to be higher before 2006 (47% vs. 24%; p=0.0584). The cumulative incidence of chronic GVHD was statistically different (56% vs. 30%; p=0.0241).

The estimated probability of TRM at day 100 was 12% in the first group vs. 0 % in the second group (p=0.077) and did not differ between groups at 2 years. (18% vs. 23% (p =0.537)).

The overall survival (OS) at two years was 60% vs 70% in the first and second group respectively (p=0.1784). The progression-free survival (PFS) tended to be different at 2 years (45% vs. 65% (p=0.056)). The median of PFS is 22 months for patients transplanted prior 2006 and is not reached in the second group (p=0.1811). In our study there was no significant difference in OS or TRM between the 2 groups in multivariate analysis; only the number of previous auto-SCT with more than two high dose chemotherapies has a negative impact on the OS. There was a significant difference in the incidence of relapse between the 2 groups in the multivariate analysis.

Although we cannot carry out the impact of other changes related to our practice in the same period, these data suggests an impact in transplant outcomes of novel drugs introduced in the therapy of MM (lower TRM, GVHD and higher disease control). This piece of information, if confirmed, should be taken into considerations for present and future approaches.