[Impact of minimal residual disease detection after treatment of multiple myeloma]

Prognostic impact of the detection of minimal residual disease (MRD) in multiple myeloma (MM) has been confirmed in numerous studies.

Retrospective examination of our patient database (107 newly diagnosed multiple myelomas between 2007 and 2017). Flow cytometry (FCM) was performed as MRD assessment.

MRD assessment was performed in 56 patients (median age: 68 years), after induction treatment of multiple myeloma. The treatment contained bortezomib in 91%, autologous haematopoetic stem cell transplantation (ASCT) was perfomed in 50%. MRD detection was performed on bone marrow samples, predominantly in our hospital (BD FACScan, 3 colour, panel: CD38, CD138, CD19, CD45, CD56, CD28, CD117, cyKappa, cyLambda, 100 000 events).

SPSS 13.0.

The progression-free survival (PFS) and the overall survival (OS) were significantly longer in MRD negative (n = 22) patients (PFS: 54 months, OS: 79% after 5 years) than MRD positive patients (n = 34, PFS: 22 months, OS 21% after 5 years, p = 0.001). Patients achieving complete response (CR) (n = 29) have different PFS (MRD negative CR: 60 months, MRD positive CR: 21 months, p<0.001). Patents achiving MRD negative very good partial response (n = 5) have similar PFS (54 months) as patients with MRD negative CR. The longest PFS (68 months) was observed in MRD negative patients, after ASCT (n = 11), while the PFS was significantly (p<0.001) shorter in patients who were MRD positive after ASCT (n = 18, PFS: 25 months), similarly in MRD positive patients without ASCT (n = 15, PFS 21 months). Cox regression analysis (stage, cytogenetic risk, ASCT) confirmed that MRD is an independent prognostic factor of PFS and OS. We did not find significant relationship between MRD and stage, cytogenetic risk, number of treatment cycles, ASCT.

The depth of response after induction treatment of MM is an independent predictor of survival. MRD assessment with FCM is recommended to define response. Consideration of maintenance treatment in MRD positive patients and eradication of MRD are also recommended. Orv Hetil. 2019; 160(13): 502-508.