Enhanced Detection of Multiple Myeloma Cells by Next-Generation Flow Cytometry Following Density Gradient Medium...

Following treatment, relapse of Multiple Myeloma (MM) occurs due to measurable residual disease (MRD). As therapeutic options expand, advances in response assessment become more critical, necessitating more sensitive MRD detection methods.

This study aimed to improve the efficiency and sensitivity of a flow cytometry assay for MM MRD detection in blood and bone marrow. To achieve this, three pre-enrichment methods were compared using 32 samples from patients with active MM and 122 samples from MM patients in remission. The methods compared were the Euroflow recommended erythrocyte bulk lysis (BL) method, density gradient medium (DGM) separation and negative selection (NS).

By removing granulocytes, DGM facilitated the processing of a larger starting quantity of white blood cells (WBCs) (> 60 × 10⁶) compared to BL (20 × 10⁶), achieving greater analytical sensitivity with a limit of detection of 5.2 × 10^-7 vs. 2 × 10^-6. DGM separation also features a shorter processing time and is more cost-effective. Although NS can also process large quantities of WBCs, the need for extra processing steps and substantially higher costs made this method the least suitable choice for clinical implementation.

Pre-enrichment via DGM separation can cost-effectively reduce sample processing times and significantly increase the analytical sensitivity of MM MRD analysis.