OVERVIEW
Multiple myeloma is a clonal bone marrow disease characterized by the neoplastic transformation of terminally differentiated B cells that secrete a homogeneous (monoclonal) immunoglobin called an M-protein or paraprotein. Multiple myeloma is characterized by excess bone marrow plasma cells, monoclonal proteins, osteolytic bone lesions, renal impairment, anemia, and immunodeficiency.
Myeloma can progress through stages that in some cases may include a pre-malignant monoclonal expansion of plasma cells called monoclonal gammopathy of undetermined significance (MGUS) which is characterized by <10% plasma cells in the bone marrow, monoclonal protein spike, and no end organ damage. It may also include smoldering myeloma or asymptomatic myeloma which shows 10-30% plasma cells in the bone marrow but no osteolytic lesions, anemia or other features of malignant myeloma.
PRE-TREATMENT CLONOTYPING
IMPORTANT: While this test remains in development at CGL, specimens obtained at diagnosis are presently required such that a baseline clonotype can be determined. Later MRD assessments are predicated on identification of this clonotype.
TEST REQUIREMENTS
- Completed CGL Lymphoid or Myeloid Testing requisition form [link]
- 2mL bone marrow aspirate (in EDTA – please see our Guidelines/Policies for Samples and Transport)
TRANSPORT
Click here for guidelines on transporting specimens.
METHOD
Content in development
CLINICAL UTILITY
While multiple myeloma is a clonal neoplasm, it is anticipated that approximately 5% of patients will not have a clonotype identifiable by this assay. Later measurable residual disease (MRD) assessments must therefore be performed by orthogonal methods (eg high sensitivity flow cytometry).
TURN AROUND TIME
As treatment decisions are not predicated on results of this test, it is anticipated that testing will be performed quarterly.
SELECTED REFERENCES
- Pieter?Sonneveld, et al, (2024) Daratumumab, Bortezomib, Lenalidomide, and Dexamethasone for Multiple Myeloma NEJM 390:301-313. (PMID: 38084760)