Positron Emission Tomography - Computed Tomography (PET-CT) using fluorine-18 fluorodeoxyglucose is a functional imaging diagnostic tool which is widely used In several neoplastic conditions, at initial staging, for restaging in suspected disease relapse and for assessing the response to treatment. Most patients with multiple myeloma (MM) exhibit a high-glycolytic activity rate and therefore they are FOG-avid, especially at the disease relapse. The priceless value of 18F-FOG PET-CT in the therapeutic assessment for several treatment schemes, including aSCT, has been highlighted by several studies: particularly, the occurrence of negative PET-CT after a double aSCT in MM patients with clinical complete response or very good partial response positively correlates with favourable PFS and overall survival (OS). likewise, persistence of 18F-FDG avid disease in MM patients achieving a clinical complete response constitutes a poor prognostic factor. Primary objective of this prospective, observational, non-pharmacological, multicentric study is to evaluate the role of 18F-FDG PET-CT for assessing early response after 6 months of treatment with daratumumab in patients with .relapsed/refractory MM.

Inclusion Criteria:

• patients with refractory multiple myeloma who relapsed after therapy with daratumumab in combination with dexamethasone + bortezomib or dexamethasone + lenalidomide;
• patients capable of expressing informed consent.

Exclusion Criteria:

• patients with clinical contraindications to the administration of daratumumab;
• patients with coexisting non-hematological neoplastic condition;
• patients< 18 years;
• patients uncapable of expressing informed consent.

patients with refractory multiple myeloma who relapsed after therapy with daratumumab in combination with dexamethasone + bortezomib or dexamethasone + lenalidomide.