Multicolor flow cytometry (MFC) is widely used for measurable residual disease (MRD) detection in acute myeloid leukemia (AML), currently recommended to perform on bone marrow (BM) aspirate only. However, BM aspiration is invasive and sometimes inadequate, whereas 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, p0.001). The assay was then prospectively evaluated in 118 patients, including 63 newly diagnosed AML in post-induction (24 intensive and 30 less intensive) remission 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 reference, PB testing showed 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=0.002), correlation was significant (r=0.6, p=0.003). Importantly, PB MRD positivity predicted relapse-free and overall survival in the full cohort (p0.01 for both) and also post-induction subgroup (p=0.0708 and p=0.0021 respectively). These findings demonstrate that PB MFC-MRD testing is feasible, robust, and clinically informative, supporting PB as a promising complementary specimen for MRD assessment.
Li et al. (Fri,) studied this question.