Allogeneic Stem Cell Transplantation vs. Conventional Therapy as Salvage Therapy for Relapsed / Progressive Patients With Multiple Myeloma After First-line Therapy

Inclusion Criteria:

Patients eligible for study inclusion must meet criteria 1- 7 at registration and all of the following criteria before randomization:

1. Multiple Myeloma

2. Age 18 - 65 years

3. A signed informed consent form must be obtained before participation in the study

4. Age 66 - 70 years, if comorbidity index according to Sorror score = 0 and ECOG ≤ 1

5. 1st relapse/ progression according to IMWG criteria after first-line therapy (consisting of induction therapy followed by autologous transplantation once ortwice and maintenance therapy), Additionally: meeting the need for treatment basedon the SLiM-CRAB-criteria

6. Negative pregnancy test in female patients

7. Maximum of 1 cycle salvage therapy prior to study inclusion

8. Availability of a fully compatible stem cell donor (HLA-ident. Sibling or 10/10 MUDor 9/10 MMUD if mismatch affects DQB) after 3 cycles salvage therapy

9. CR/PR or SD according to IMWG-criteria after 3 cycles salvage therapy within thestudy

Exclusion Criteria:

Patients are excluded from the study if any one of criteria 1-6 are met at registration and if criterion 7 is met before randomization:

1. Non-sufficient organ function defined as: Bilirubin (in the absence of Meulengracht's disease), SGPT or SGOT ≥3 higher thannormal values Cardiac ejection fraction ≤ 50% GFR < 30 ml/min DLCO < 35 % orcontinuous oxygen dependency

2. Active hepatitis B or C infection or uncontrolled HIV infection

3. Other, active malignant disease

4. Prior treatment with allogeneic stem cells

5. Participation in a clinical trial or taking an IMP within 30 days or five times thehalf-life of the IMP, whichever is longer, prior to registration

6. Positive serum pregnancy test at screening and before first treatment orbreastfeeding

7. PD under salvage therapy