Real World Criteria Used to Diagnose Relapsed/Refractory Status of Patients With Multiple Myeloma in Germany

OBJECTIVES: To identify key criteria used in routine practice in Germany to classify relapsed and/or refractory multiple myeloma (RRMM) in patients experiencing progressive disease (PD). Secondly, to understand how these classification and applied PD criteria align with the International Myeloma Working Group (IMWG) guideline.

METHODS: An online anonymized cross-sectional study with a survey was sent to physicians and a Delphi panel of MM experts in 2021. Information about 8 key IMWG criteria indicative of PD were collected. The survey described 18 hypothetical case scenarios fulfilling the IMWG definitions of “primary refractoriness” (n=7), “relapsed only” (n=2), “relapsed and refractory” (n=6), or “neither relapsed only nor relapsed and refractory” (n=3). Consensus was considered to be reached when 85% of physicians (survey) or 80% of experts (Delphi panel) had similar answers.

RESULTS: Among the 41 haemato-oncologists participating in the survey, a consensus was reached for 1 of the 8 (13%) key PD criteria: free light chain (FLC)-ratio. In the Delphi panel (n=9), consensus was reached for 3 (38%) PD criteria: FLC-ratio, serum M-protein electrophoresis, and soft tissue plasmacytomas/bone lesions. Of the 18 case scenarios, consensus among physicians or the expert panel was reached for 6 (33%) and 9 (50%) cases, respectively. The classification of “primary refractoriness” cases generally matched the IMWG criteria (Physicians: 5 of 7; Delphi panel: 6 of 7).

CONCLUSIONS: In this study, a German panel of MM experts identified three criteria as key diagnosis criteria of PD. Consistency in the classification of RRMM was mainly found for primary refractory MM. The lack of alignment on the RRMM status observed in this study may be due to the complexity of RRMM diagnosis and treatment schemes making it difficult to deal with hypothetical patient cases. Future studies are needed to identify relevant factors used to classify RRMM in practice.