Prospective Head-To-Head Comparison of a 10-Color Single-Tube Flow Cytometry and EuroFlow Next-Generation Flow in Multiple Myeloma Minimal Residual Disease.

BACKGROUND: Minimal residual disease (MRD) assessment by next-generation flow cytometry (NGF) is an important prognostic tool in multiple myeloma (MM). Although the EuroFlow NGF assay provides highly standardized and sensitive MRD detection, its dual-tube workflow requires larger sample volumes and longer processing time, potentially limiting efficiency in routine clinical practice. This prospective study evaluated a 10-color single-tube (ST-10C) MRD assay by directly comparing its analytical and clinical performance with the EuroFlow NGF assay. METHODS: MRD analysis was performed in 40 patients with MM, of whom 39 who achieved very good partial response or complete response were included in the final analysis. Each sample was analyzed in parallel using both assays. Analytical sensitivity, qualitative and quantitative agreement, and progression-free survival (PFS) were assessed. RESULTS: Both assays achieved analytical sensitivity below 10-5. MRD was detected in 48.7% of samples by the ST-10C assay and in 38.5% by the EuroFlow NGF assay, with substantial agreement (κ = 0.79). Concordance remained high using the clinical MRD cutoff (≥ 0.001%) (κ = 0.84). Quantitative MRD levels showed strong correlation between the assays (ρ = 0.964) without significant systematic bias. MRD-positive patients showed a trend toward inferior PFS compared with MRD-negative patients by both assays. CONCLUSIONS: The ST-10C assay demonstrated analytical performance comparable to the EuroFlow NGF assay, supporting its adoption as a more efficient and streamlined alternative for routine MRD assessment in MM.