Method Description

Flow cytometric immunophenotyping for minimal residual disease (MRD) of bone marrow is performed using the following antibodies:

Tube 1: CD138, CD27, CD38, CD56, CD45, CD19, CD117, and CD81.

Tube 2: CD138, CD27, CD38, CD56, CD45, CD19, cyKappa, and cyLambda.

Abnormal plasma cell populations are detected through demonstrating CD38 (multi-epitope) and CD138 positivity along with immunoglobulin light chain restriction (ie, the presence of either predominately kappa or lambda immunoglobulin light chains) and abnormality of CD56, CD117, CD27, CD81, CD19 and/or CD45 expression.

The sensitivity of this assay is conservatively estimated to be 0.001% (1 x 10[-5]) with a minimum number of 2 x 10(-6) total events collected, and an abnormal plasma cell immunophenotype detected in a cluster of at least 20 cells and can be as high as 0.0002% (2 x 10[-6]). The sensitivity of the assay will be lower in samples with less than 2 x 10(-6) total events acquired. The validated limit of detection (sensitivity) meets the current National Comprehensive Cancer Network, International Myeloma Working Group, and EuroFlow guidelines for MRD assessment by flow cytometry in multiple myeloma. The percentage of clonal plasma cells estimated by flow cytometry is affected by specimen processing and antigen loss with specimen aging. MRD reporting is affected by sample volume and cellularity.(Unpublished Mayo method)