A Longitudinal Evaluation of Euroflow and Combined Quantitative Immunoprecipitation (QIP) and Free Light Chain (FLC) Mass Spectometry (MS) in Functional High Risk Multiple Myeloma

Introduction: The achievement of minimal residual disease (MRD) negativity is being increasingly recognised as the optimal measure of therapeutic response for both newly diagnosed and relapsed and/or refractory multiple myeloma (MM) patients. Bone marrow (BM) evaluation with either Next Generation Sequencing (NGS) or Next Generation Flow-cytometry (NGF) affords a high level of sensitivity and the attainment of MRD negativity (< 1 in 10-5 MM cells) with either approach is a powerful predictor of superior progression free survival (PFS). Both, however, are limited by the requirement for invasive bone marrow biopsy and the technical limitations imposed by variability in sample quality. Moreover, we and others have demonstrated the presence of significant spatial heterogeneity in MM that increases in the context of disease progression. Against this background we have evaluated a blood-based strategy for disease burden evaluation, Quantitative ImmunoPrecipitation (Mass Spectometry (QIP MS) and Free Light Chain Mass Spectometry (FLC MS) in a uniformly treated cohort of functional high-risk MM patients also undergoing sequential NGF (EuroFlow platform) MRD evaluation. Methods: Newly diagnosed MM patients failing (