FDA Grants Extended 510k Clearance For Light Chain Assay for the Detection of MGUS

A serum free light chain assay (SFLC) (Optilite Freelite; Thermo Fisher Scientific, Inc) for the detection of monoclonal gammopathy of undetermined significance (MGUS) received an extended 510k clearance from the FDA. The decision offers clinics and care centers continued access to accurate, sensitive diagnostic methods that identify patients with plasma-cell disorders at risk of developing multiple myeloma (MM) and other monoclonal gammopathies.

The underlying causal mechanism of MGUS is unknown and there are no associated symptoms, leading to the underdiagnosis of the disorder and subsequent delayed opportunities to test preventative strategies. Image Credit: © dwoow - stock.adobe.com

MGUS is an asymptomatic plasma cell dyscrasia characterized by the presence of abnormal monoclonal proteins in the blood. It is a precursor to various hematological malignancies including MM or other monoclonal gammopathies, such as light chain amyloidosis or lymphoproliferative disorders. MGUS is the most common plasma-cell disorder diagnosed by presence of monoclonal immunoglobulin concentrations in serum of 3 g per deciliter or less, the absence of lytic bone lesions, anemia, hypercalcemia, and renal insufficiency, and a proportion of plasma cells in the bone marrow of 10% or less.^1-3

The underlying causal mechanism of MGUS is unknown, and there are no associated symptoms, leading to the underdiagnosis of the disorder and subsequent delay in opportunities to test preventative strategies. Clinicians suggest that some risk factors may include infection, immune system disruption, or environmental factors, but further research is needed. MGUS typically affects individuals over the age of 50 and is more prevalent in men and Black populations, who have a 2- to 3-fold higher risk. Progression of MM or other related disorders is 1% per year and does not decrease overtime, meaning patients will require indefinite routine follow-ups to monitor indications of advancing disease.^2,3

Traditionally, MGUS is diagnosed through a serum protein electrophoresis (SPEP), which separates proteins in the blood or urine based on their electrical charge. SPEPs give clinicians a broad view of the overall protein composition to confirm the presence and type of monoclonal proteins compared with SFLCs, which measure kappa and lambda free light chains (FLC) in serum. The sensitivity and specificity of the test enables the identification of small concentrations of FLC proteins that are undetectable by SPEP.⁴

As research continues to uncover more about the risk factors and progression of MGUS, tools like the SFLC assay will remain invaluable in clinical practice, enabling earlier detection and potentially more effective intervention strategies for patients at risk of progressing to MM and other serious conditions.

“[SFLC] assays are trusted by health care professionals globally, and with the new claim, and as a key part of laboratory diagnostics tools, we can help health care providers continually evaluate patients with MGUS, which is important to understand the disorder and the progression to pathological malignancies,” said Hamid Erfanian, vice president and general manager of protein diagnostics at Thermo Fisher Scientific, in a news release. “Earlier identification of MGUS will enable more effective monitoring of disease progression and need for treatment, ultimately improving patient outcomes.”⁵

References

1. Monoclonal gammopathies. John Hopkins Medicine. Accessed July 29, 2024. https://www.hopkinsmedicine.org/health/conditions-and-diseases/monoclonal-gammopathies#:~:text=Monoclonal%20gammopathies%20are%20conditions%20in%20which%20abnormal%20proteins%20are%20found,lab%20test%20called%20protein%20electrophoresis

2. Kyle R, Therneau T, Rajkumar V, et al. Prevalence of monoclonal gammopathy of undetermined significance. N Engl J Med. March 30, 2006. doi: 10.1056/NEJMoa054494

3. Korde N, Kristinsson S, Landgren O. Monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM): novel biological insights and development of early treatment strategies. Blood. May 26, 2011. doi:10.1182/blood-2011-01-270140

4. Protein electrophoresis (blood). University of Rochester Medical Center. Accessed July 29, 2024. https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=protein_electrophoresis_serum#:~:text=What%20is%20this%20test%3F,abnormal%20substances%20called%20M%20proteins

5. Thermo fisher scientific announces extended 510k clearance of freelite assays for evaluation of mgus, a precursor to multiple myeloma. Business Wire. July 29, 2024. Accessed July 29, 2024. https://www.businesswire.com/news/home/20240729263978/en/Thermo-Fisher-Scientific-Announces-Extended-510k-Clearance-of-Freelite-Assays-for-Evaluation-of-MGUS-a-Precursor-to-Multiple-Myeloma