Thalidomide + Dexamethasone as Maintenance after Single Autologous Stem Cell Transplantation Improves Progression-Free Survival (PFS) in Advanced Multiple Myeloma. A Prospective Brazilian Randomized Trial

Abstract

Abstract Introduction: Autologous stem cell transplantation (ASCT) remains the mainstay of treatment of multiple myeloma (MM) in patients <65 years old. However, most patients relapse after ASCT suggesting that additional treatment is needed. The Brazilian Multiple Myeloma Group designed a study to evaluate the impact of thalidomide maintenance after ASCT. Methods: From October 2003 to July 2008, 212 untreated patients <70 years old were enrolled in a prospective randomized multicenter study. All patients signed an informed consent and the protocol was approved by the Ethical Committees of each center. The treatment consisted of 3 phases: induction with 3–5 cycles of VAD; high-dose cyclophosphamide (4g/m2) plus G-CSF for stem cell mobilization; (3) melphalan 200 mg/m2 and ASCT. On day +60 post ASCT patients were randomized to receive dexamethasone (40 mg/d × 4 days every 28 days) with (arm A) or without (arm B) thalidomide (200 mg daily) for 12 months or until disease progression. Results: The median age was 55 years (27–70), 52% were male, the median serum beta-2 microglobulin was 3.66 mg/dl, 33% were ISS stage 3, 36% were ISS stage 2 and 24% had deletion of chromosome 13. In July of 2008, 93 patients (44%) were randomized: 54 in arm A and 39 in arm B. Reasons for non-randomization were: treatment related deaths during phases 1–3 (n= 39), disease progression (n= 22), ineligible or refused ASCT (n= 7), SMD after ASCT (n= 1), protocol violation (n= 3), abandoned (n= 19), and still in phases 1–3 (n= 28). Clinical characteristics of each group were similar. The median follow-up from diagnosis was 15 months. PFS in arms A and B were 42% (95% confidence interval [CI] 22–62) and 25% (95% CI 5–45), p= 0.07. A multivariate analysis that included baseline serum beta-2-microglobulin and deletion of chromosome 13 showed that maintenance with thalidomide was significantly associated with better PFS (hazard ratio 2.43, 95% CI 1.10–5.35, p=0.03). Overall survival was 65% in arm A (95% CI 35–95) and 74% in arm B (95% CI 44–100), p= NS. Conclusions: A high proportion of MM in Brazil has advanced disease at diagnosis, and this explains the high number of patients who did not reach the maintenance phase. This study shows that the addition of thalidomide to dexamethasone improves PFS after a single ASCT.