Superiority of melphalan-prednisone (MP) + thalidomide (THAL) over MP and autologous stem cell transplantation in the treatment of newly diagnosed elderly patients with multiple myeloma

Abstract

1 Background: The standard MP regimen remains the reference treatment for elderly patients (pts) with multiple myeloma (MM). In May 2000, we initiated the IFM 99–06 trial, for pts aged 65–75 y, comparing MP (12 courses at 6 weeks intervals) to MP-THAL (MP plus THAL at the maximum tolerated dose, but ≤ 400 mg/day) and a MEL100-based treatment (VAD×2, CTX 3g/m2, and 2 courses of MEL100 mg/m2). Methods: IFM99–06 was planned to enroll 476 evaluable pts, whose treatment allocation followed a 3 (MP), 2 (MP-THAL), 2 (MEL100) randomization scheme. The primary end-point was overall survival (OS). Secondary end-points were response to treatment and progression-free survival (PFS). Two interim analyses were planned and reviewed by a Data Safety Monitoring Board (DSMB) independent of IFM. At the second interim analysis, the DSMB suggested that a third interim analysis be performed with a date of point on May 1, 2005. Results: At this time, 436 pts had been enrolled, 191, 124 and 121 in MP, MP-THAL and MEL100 groups, respectively. The median (se) follow-up time was 32.2 (1.8) months (mo.). Median (se) PFS times were 17.2 (1.5), 29.5 (3.6) and 19.0 (1.3) mo. in MP, MP-THAL and MEL100 groups, respectively. The PFS time was significantly longer in the MP-THAL group than in the MP group (RR=2.4, P<0.0001), but no significant difference was noted between MP and MEL100 groups (RR=1.2, P=0.12). There was a clear advantage in favor of MP-THAL vs MEL 100 (RR=2.0, P=0.0001). The PFS advantage in favor of MP-THAL translated to a significant benefit in terms of OS. Median (se) OS times were 30.3 (5.8) mo. (86 deaths), not reached at 56 mo.(34 deaths) and 38.6 (3.0) mo. (54 deaths) in MP, MP-THAL and MEL100 groups, respectively. The OS time was significantly longer in MP-THAL group than in MP group (RR=1.9, P=0.0008), but not significantly different between MP and MEL100 groups (RR=1.1, P=0.55). MP-THAL was also superior to MEL100 (RR=1.7, P=0.014). Conclusion: Since these results show the superiority of MP-THAL, enrollment was stopped. The final analysis will be presented at the meeting. MP-THAL should be, at the present time, the reference treatment for newly diagnosed MM pts ineligible for high-dose therapy. No significant financial relationships to disclose.