This trial is a randomised, parallel-group, multicenter phase III study for maintenance therapy with lenalidomide in patients with multiple myeloma who were treated with high-dose therapy and autologous stem cell transplantation as first line therapy.

High-dose therapy will be performed as first line treatment. After high-dose therapy and autologous stem cell transplantation the patients will be included and randomised. Three month after high-dose therapy all patients will receive consolidation therapy with 6 cycles of lenalidomide 25 mg daily for 21 days every 28 days. Afterwards patients will receive maintenance therapy according to their assigned treatment arm. Randomisation will be performed in a 1:1 ratio to continuous maintenance therapy with either 25mg or 5mg lenalidomide daily for 21 days every 28 days.Randomisation will be stratified by ISS-stage (1+2 vs 3, age (younger than 66 years versus 66 years or older), response after high-dose therapy (CR+vgPR vs PR vs MR/SD. Patients will be treated until disease progression.

Inclusion Criteria:

• Signed informed consent form

• Age 18-75 years

• Able to adhere to the study visit schedule and other protocol requirements

• Patients with multiple myeloma who have received high-dose therapy and autologous stem cell transplantation as first-line therapy within the last 90 - 120 days and have not shown progressive disease afterwards.

• Patients may have received up to 6 cycles of prior induction therapy and up to 2 cycles of prior mobilisation chemotherapy. A bortezomib or thalidomide induction therapy is allowed. Patients may also have received prior radiation therapy

• Measurable levels of myeloma paraprotein in serum (>0.5 g/dL) or urine (>0.2 g/24hours) or measurable free light chains (FLC) in serum (>50 mg/l) with an abnormal FLC ratio must be documented at the time of first diagnosis.

• ECOG performance status = 2 at study entry

• Laboratory and functional test results within these ranges:

  • ANC ≥ 1,000/μL
  • Platelet count ≥ 100,000/μL
  • Total bilirubin 2.5 mg/dL
  • AST (SGOT) and ALT (SGPT) 3 x ULN
  • Patients with impaired renal function can be included

• The patient must be able to adhere to the pregnancy precautions

• Disease free of prior malignancies for 5 years with exception of currently treated basal cell, squamous cell carcinoma of the skin, or carcinoma "in situ" of the cervix or breast

Exclusion Criteria:

• Any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from signing the informed consent form
• Pregnant or breast feeding females
• Any condition or laboratory abnormality which places the subject at an unacceptable risk if he/she were to participate in the study or confounds the ability to interpret data from the study
• Known allergic/hypersensitivity reaction to thalidomide, lenalidomide or any components of the treatment
• Any cutaneous grade ≥ 3 adverse reaction (for example desquamating rash) while taking thalidomide or similar drugs
• Any prior use of lenalidomide
• Known positive for HIV or active infectious hepatitis, type A, B or C