Pre-Analytic Stabilization of Bone Marrow Aspirates for Acute Myeloid Leukemia Measurable Residual Disease Testing by Spectral Flow Cytometry

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy in which detection of measurable residual disease (MRD) after treatment roughly halves 5-year overall survival (68% vs 34%). Multiparameter flow cytometry is used in ~60% of AML MRD assessments, but it must reliably identify leukemic populations present at frequencies as low as 0.01–0.1% of total cells. ELN guidelines recommend acquiring at least 500,000–1,000,000 CD45+ events with adequate cell viability to achieve this limit of detection.

Acquiring this amount of cells depends heavily on sample quality, which is difficult to control outside specialized laboratories. With current workflows, bone marrow must be processed within 24–72 hours of collection, and even within that window, storage and transit time disproportionately degrade myeloid populations, particularly monocytic lineages, central to AML MRD. As a result, high-quality MRD testing is largely limited to centers capable of rapid processing, restricting access for community hospitals, and introducing variability that can confound results across sites.

A method for stabilizing bone marrow at collection could decouple sample acquisition from analysis, enabling community sites to collect and fix specimens locally for shipment to a central reference laboratory. This would expand access to standardized MRD testing while preventing sample degradation. We evaluated whether TokuKit fixation can stabilize bone marrow at collection, preserving the cellular populations and marker expression required for downstream spectral flow cytometric MRD analysis.