Table 5.
International Myeloma Working Group uniform response criteria for multiple myeloma29
| Response subcategory | Response criteria |
|---|---|
| Complete responsea (CR) | Negative immunofixation of serum and urine and Disappearance of any soft tissue plasmacytomas, and <5% plasma cells in bone marrow |
| Stringent complete response (sCR) | CR as defined above plus |
| Normal FLC ratio and | |
| Absence of clonal cells in bone marrow by immunohistochemistry or immunofluorescence | |
| Very good partial response (VGPR)a | Serum and urine M-component detectable by immunofixation but not on electrophoresis or ≥90% or greater reduction in serum M-component plus urine M-component <100 mg per 24 h |
| Partial response (PR) | ≥50% reduction of serum M protein and reduction in 24-h urinary M protein by ≥90% or to <200 mg per 24 h If the serum and urine M protein are unmeasurable, a ≥50% decrease in the difference between involved and uninvolved FLC levels is required in place of the M protein criteria |
| If serum and urine M protein are unmeasurable, and serum free light assay is also unmeasurable, ≥50% reduction in bone marrow plasma cells is required in place of M protein, provided baseline percentage was ≥30% | |
| In addition to the above criteria, if present at baseline, ≥50% reduction in the size of soft tissue plasmacytomas is also required | |
| Stable disease (SD) | Not meeting criteria for CR, VGPR, PR or progressive disease |
| Progressive disease (PD)a | Increase of 25% from lowest response value in any one or more of the following: |
| Serum M-component (absolute increase must be ≥0.5 g/100 ml)c and/or | |
| Urine M-component (absolute increase must be ≥200 mg per 24 h) and/or | |
| Only in patients without measurable serum and urine M-protein levels: the difference between involved and uninvolved | |
| FLC levels (absolute increase must be >10 mg/l) | |
| Bone marrow plasma cell percentage (absolute % must be ≥10%) | |
| Definite development of new bone lesions or soft tissue plasmacytomas or definite increase in the size of existing bone lesions or soft tissue plasmacytomas | |
| Development of hypercalcemia (corrected serum calcium >11.5 mg/100 ml) that can be attributed solely to the plasma cell proliferative disorder |
Note clarification to IMWG criteria for coding CR and VGPR in patients in whom the only measurable disease is by serum FLC levels: CR in such patients is defined as a normal FLC ratio of 0.26–1.65 in addition to CR criteria listed above. VGPR in such patients is defined as a >90% decrease in the difference between involved and uninvolved free light chain (FLC) levels.
All response categories (CR, sCR, VGPR and PR) require two consecutive assessments made at any time before the institution of any new therapy; complete, PR and SD categories also require no known evidence of progressive or new bone lesions if radiographic studies were performed. Radiographic studies are not required to satisfy these response requirements. Bone marrow assessments need not be confirmed.
Adapted with permission from Durie et al.29
for progressive disease, serum M-component increases of ≥1 gm/100 ml are sufficient to define relapse if starting M-component is ≥5 gm/100 ml.