Optilite® Freelite Mx Kappa Free Kit; Optilite® Freelite Mx Lambda Free Kit

The Optilite Freelite Mx Kappa and Lambda Free Kits are quantitative in vitro immunoturbidimetry assays that measure free light chains in serum and urine. They aid in diagnosing and monitoring multiple myeloma, lymphocytic neoplasms, Waldenström's macroglobulinemia, AL amyloidosis, light chain deposition disease, and connective tissue diseases like systemic lupus erythematosus; they also evaluate monoclonal gammopathy of undetermined significance (MGUS) in serum.

Both proposed and predicate devices use the same quantitative immunoturbidimetry assay type, detect the same analytes (Kappa and Lambda free light chains), employ identical detection antibodies (sheep anti-human antibodies bound to latex particles), and share the same reference intervals and calibrator traceability. The main difference is that the proposed device runs on the Optilite Analyzer while the predicate runs on the Siemens BN II system, and the proposed device has extended measuring ranges and different urine reference intervals.

The submission references CLSI C56-A for sample centrifugation guidance and adapts the 25% free light chain change criterion from International Myeloma Working Group (IMWG) guidelines for multiple myeloma monitoring.

The assay methodology, analytes measured, and detection principles are identical to the predicate. No changes were made to the test principle or reagent composition. Clinical performance studies demonstrate the proposed device achieves a 56.3% positive rate in MGUS patients (100% in light chain MGUS) and 91.9% negative rate in non-MGUS disease controls, supporting the new MGUS evaluation claim. The device differences (analyzer platform and measuring ranges) do not raise safety or efficacy concerns because the underlying assay is unchanged and clinical data show it reliably detects MGUS when used according to labeling.