Campbell et al.  prospectively compared HLC and FLC assays with standard IMWG criteria and multiparameter flow cytometry (MFC) to assess minimal residual disease (MRD) in 23 patients who had received an autologous stem cell transplant. MFC was the most sensitive method to identify residual disease, and MFC negativity correlated with improved outcome (PFS = not reached vs. 21 months, p=0.01). However, the authors comment that MFC is challenging to implement in routine practice due to suboptimal bone marrow sampling and the need for repeated biopsies. Therefore, a ROC analysis was performed to compare the ability of HLC and FLC assays to predict MFC status. Normalisation of both HLC and FLC ratios predicted MFC negativity with a sensitivity and specificity of 100% and 82%, respectively, and the authors concluded that a HLC and FLC normalisation post-transplant is a useful surrogate marker for flow MRD negativity.