multiple myeloma, novel agents, daratumumab, extramedullary disease

The treatment of multiple myeloma (MM) has changed substantially during the past two decades. The incorporation of novel agents into therapeutic strategies has resulted in prolonged overall survival of MM patients with approximately 15% of them being considered operationally cured [1]. Extramedullary myeloma disease (EMD) is a less frequent manifestation of MM occurring either at the time of diagnosis (11.0–23.7%) or, more often, during the course of the disease (24–37%), where myeloma plasma cells (PCs) become independent of the bone marrow (BM) microenvironment and infiltrate distant tissues and organs [2]. There are two generally accepted subtypes of EMD: (i) soft tissue masses in extraosseous locations and (ii) bone-related masses that remain connected to the bone [3]. The presence of soft tissue EMD is always considered a high-risk feature with an aggressive phenotype, drug resistance and short survival [4], whereas the prognostic relevance of bone-related EMD remains controversial with discordant results from several analyses [5]. The incidence of EMD is increasing as the survival of MM patients is prolonged. The treatment options are the same for EMD as for MM patients without EMD and the outcome remains unsatisfactory. Daratumumab, the IgG kappa monoclonal antibody targeting CD38 antigen, has been rapidly incorporated as a backbone agent of the standard of care regimens in practically all MM stages due to its unprecedented efficacy [6]. Nevertheless, there are currently no data available regarding the activity of daratumumab in EMD.