Prospective feasibility study of peripheral blood for MRD detection in acute myeloid leukemia by flow cytometry

Multicolor flow cytometry (MFC) is widely used for measurable residual disease (MRD) detection in acute myeloid leukemia (AML) and is currently recommended to be performed on bone marrow (BM) aspirate only. However, BM aspiration is invasive and sometimes inadequate, whereas the peripheral blood (PB) offers a patient-friendly practical alternative. We first analyzed 53 paired PB and BM samples (30 MRD negative, 23 MRD positive) and observed 100% concordance with strong correlation (r = 0.945; P< .001). The assay was then prospectively evaluated in 118 patients, including 63 patients with newly diagnosed AML in postinduction remission (24 intensive and 30 less intensive), with results corroborated by molecular, cytogenetic, and follow-up data. PB MRD was positive in 26, negative in 86, and inadequate in 6, yielding 95% adequacy and 98% concordance with BM. Using BM as the reference, PB testing demonstrated 96% sensitivity, 99% specificity, 96% positive predictive value, and 99% negative predictive value. Although PB MRD levels were lower than BM (median 0.17% vs 0.84%; P = .002), correlation was significant (r = 0.6; P = .003). Importantly, PB MRD positivity predicted relapse-free survival in the full cohort (P< .01) and postinduction subgroup (P = .0021). These findings demonstrate that PB MFC-MRD testing is feasible, robust, and clinically informative, supporting PB as a promising complementary specimen for MRD assessment.