A PET-CT will be performed on patients with myeloma after a standard first-line treatment. The PET-positive patients will receive 4 cycles of Carfilzomb-Revlimid-Dexamethason (KRd), before a new PET-CT will be performed.

Patients will be evaluated for inclusion after finishing first-line therapy, or after a sufficient amount of treatment in first-line, and a sufficient respons (VGPR). Eligible performed regimens are defined in the protocol. All patients will perform a PET-CT, and PET-negative patients will be excluded from protocol treatment. The PET-positive patients will do a minimal residual disease (MRD-)evaluation in the bone marrow before entering treatment. After 4 28day cycles of Carfilzomib-Revlimid-Dexamethason, a new MRD and a new PET-CT will be performed, as measures of outcome. Patients will continue treatment as written in the protocol.

Inclusion Criteria:

1. Prior confirmed diagnosis of multiple myeloma (2014).

2. Received standard first line treatment with at least partial response. Standard first line treatment is defined as

   • VRD, VTD or VCD followed by ASCT, or
   • MPV at least 6 cycles, or no further reduction in monoclonal component the last 2 cycles, or
   • Rd at least 9 cycles or no further reduction in monoclonal component the last 2 cycles.

3. Carfilzomib naïve.

4. Eastern Cooperative Oncology Group (ECOG) performance status 0-2.

5. Absolute neutrophil count (ANC) ≥ 0,5 x 109/L) and platelet count >35 x 109/L.

6. At least very good partial remission (VGPR) from first line treatment

Exclusion Criteria:

1. Change of first line treatment because of stabile or progressive disease.
2. Major surgery within 28 days before enrollment.
3. Radiotherapy within 14 days before enrollment, but if the involved field is small, 7 days will be considered a sufficient interval before onset of the treatment.
4. Glucocorticoid therapy within the 14 days prior to inclusion that exceeds a cumulative dose of 160 mg dexamethasone or 1000 mg prednisone.
5. Central nervous system involvement.
6. Uncontrolled heart disease, including congestive heart failure (NYHA III-IV), uncontrolled angina pectoris, uncontrolled conduction abnormalities, acute diffuse infiltrative pulmonary disease, pericardial disease or myocardial infarction within 6 months prior to enrollment
7. Uncontrolled hypertension or uncontrolled diabetes despite medication
8. Active hepatitis B or C infection or known human immunodeficiency virus (HIV) positivity.
9. Another active malignancy. Patients with non-melanoma skin cancer or carcinoma in situ of any type are not excluded if they have undergone complete resection.
10. Primary plasma cell leukemia, systemic AL amyloidosis, Waldenströms macroglobulinemia, POEMS syndrome