Table 4 International myeloma working group MRD criteria [11]

Sustained MRD negative

MRD negativity in the marrow (NGF or NGS, or both) and by imaging as defined below, confirmed minimum of 1 year apart. Subsequent evaluations can be used to additionally specify the duration of negativity (e.g. MRD negative at 5 years)

Flow MRD negative

Absence of phenotypically aberrant clonal plasma cells by NGF on bone marrow aspirates using the EuroFlow standard operation procedure for MRD detection in multiple myeloma (or validated equivalent method) with a minimum sensitivity of 1 in 10⁵ or greater nucleated cells

Sequencing MRD negative

Absence of clonal plasma cells by NGS on bone marrow aspirate in which presence of a clone is defined as fewer than two identical sequencing reads obtained after DNA sequencing of bone marrow aspirates with the LymphoSIGHT platform (or validated equivalent method), with a minimum sensitivity of 1 in 10⁵ or greater nucleated cells

Imaging plus MRD negative

MRD negativity as defined by NGF or NGS plus disappearance of every area of increased tracer uptake found at baseline or a preceding PET/CT or decrease to less than mediastinal blood pool SUV or decrease to less than that of surrounding normal tissue