The purpose of this study is to determine whether a reduced intensity conditioning regimen followed by allogeneic stem cell transplantation from unrelated donors is a feasible and effective treatment for patients with multiple myeloma who failed a previous autologous stem cell transplantation.

The purpose of this study is to determine whether a reduced intensity conditioning regimen followed by allogeneic stem cell transplantation from unrelated donors is a feasible and effective treatment for patients with multiple myeloma who failed a previous autologous stem cell transplantation.

Inclusion Criteria:

• Multiple Myeloma stage II or III acc. to Salmon and Durie (chemosensitive or refractory) and relapse or progression after high dose chemotherapy with autologous stem cell support
• Age 18-60 years
• ECOG-performance status 0-1
• Availability of a HLA-compatible unrelated donor (HLA-A, -B, -DRB1, -DQB1)

Exclusion Criteria:

• Serious concomitant medical disease that would limit life span or ability to tolerate chemotherapy
• Severe cardiac failure (ejection fraction < 40%)
• Severe impairment of renal function (Creatinine clearance < 50ml/min)
• Severe impairment of liver function (bilirubine > 2 fold of upper limits of normal)
• Pregnant or lactating women
• Other major organ or system dysfunctions(GI, neurological, psychiatric dysfunctions that would impair tolerance of chemotherapy or prolonged haematological recovery)
• Positivity for HIV