Autologous peripheral blood stem cell (PBSC) transplantation is now considered standard therapy in patients (< 65 ans) with multiple myeloma. The Intergroupe Francophone du Myelome conducted a randomised trial of the treatment of multiple myeloma with high dose chemotherapy followed by either one or two successive autologous stem cell transplantation. The probabilities of event-free-survival and overall survival were doubled with a double transplant. The benefits were greatest among patients who had not had a very good partial response to the first transplant.

The aim of this multicenter randomised trial in previously untreated patients with multiple myelome (stage II, III DS)is to assess the optimal timing of a second autologous stem-cell transplant.After a first-line therapy with thalidomide-dexamethasone followed by a PBSC collection, patients are randomly assigned to receive two autologous PBSC transplants (arm A)or one autologous PBSC transplant followed by a consolidation therapy with thalidomide-dexamethasone (arm B). Patients included in the arm B will receive a second transplant in case of disease progression on consolidation therapy, or in case of relapse in responders.

Inclusion Criteria:

• patients less than 61 years of age
• Durie Salmon stage II or III
• written and informed consent

Exclusion Criteria:

• Prior treatment for myeloma
• ECOG performance score of 4
• Positive HIV test
• Chronic respiratory disease (DLco < 60%)
• Systolic ejection fraction < 50%
• Pregnant or nursing women