Table 4.
Protein electrophoresis, serum free light chains and response criteria for multiple myeloma.25
| Response | Response criteria | Comment |
|---|---|---|
| Stringent Complete Response (sCR) | CR + normal serum FLC ratio and absence of clonal plasma cells in bone marrow | Only validated for Freelite® serum free light chain assay |
| Complete Response (CR) | Negative IFE of the serum and urine <5% plasma cells in bone marrow | IFE required if paraprotein not visible by electrophoresis |
| Very Good Partial Response (VGPR) | Serum or urine paraprotein only detectable by IFE, or ≥90% reduction in serum paraprotein plus urine BJP <100 mg/day |
IFE required if paraprotein not visible by electrophoresis |
| Partial Response (PR) | ≥50% reduction of serum paraprotein, or reduction of urine BJP by ≥90% or to <200 mg/day FLC only used if paraprotein not measurable by SPEP or UPEP |
Allow use of quantitative immunoglobulin levels in patients in whom the paraprotein measurements are unreliable (e.g. IgA paraproteins co-migrating with the beta region) |
| Minimal Response (MR) | ≥25% reduction of serum paraprotein or ≥50% reduction in urine BJP |
FLC, free light chain; IFE, immunofixation; BJP, Bence Jones protein; SPEP, serum protein electrophoresis; UPEP, urine protein electrophoresis