Myeloma Response Criteria

International Myeloma Working Group uniform response criteria

CategoryCriteria
Stringent complete response (sCR)CR as defined below PLUS:
Normal SFLC ratio, AND
Absence of clonal plasma cells in marrow by immunohistochemistry or flow cytometry
Complete response (CR)Negative immunofixation on the serum and urine, AND
Disappearance of any soft tissue plasmacytomas, AND

≤ 5% plasma cells in bone marrow
Very good partial response (VGPR)Serum and urine M-protein detectable by immunofixation but not on electrophoresis, OR
≥ 90% reduction in serum M-protein plus reduction in 24h urinary M-protein by > 90% or to < 100 mg/24h
Partial response (PR)≥ 50% reduction of serum M-protein, AND
reduction in 24h urinary M-protein by ≥ 90% or to < 200 mg/24h, AND
≥ 50% reduction in the size of any plasmacytomas present at baseline
(In place of M-protein criteria: If serum + urine M protein unmeasurable, ≥ 50% decrease in difference between involved and uninvolved SFLC levels, OR
If serum + urine M-protein + SFLC assay also unmeasurable, a ≥ 50% reduction in marrow plasma cells is required, provided baseline bone marrow plasma cell percentage was ≥ 30%)
Stable disease (SD)Not meeting criteria for CR, VGPR, PR or progressive disease
Progressive disease (PD)At least ONE of the following:
> 25% increase in serum M-protein in 3 months (absolute increase must be > 5 g/L), OR
> 25% increase in urine M-protein in 3 months (absolute increase must be > 200 mg/24h), OR
> 25% increase in the difference between involved and uninvolved SFLC levels (applicable only to patients without measurable serum and urine M- protein (absolute increase must be > 10 mg/dL), OR
> 25% increase in bone marrow plasma cell percentage (absolute percentage must be > 10%), OR
Development of new bone lesions or soft tissue plasmacytoma, OR
Development of hypercalcaemia
Clinical relapseRequires at least one of the following:
Development of new bone lesions or soft tissue plasmacytoma, OR
Increase in size of existing plasmacytomas or bone lesions, OR
Any of the following attributable to myeloma: Development of hypercalcaemia, Development of anaemia (drop in Hb > 2 g/dL), Rise in serum creatinine
Relapse from CRRequires at least one of the following:
Reappearance of serum or urine M-protein by immunofixation or electrophoresis, OR
Development of > 5% plasma cells in the bone marrow, OR
Appearance of any other sign of progression (eg new plasmacytoma, new lytic bone lesion)

These International Response Criteria for myeloma were developed by the International Myeloma Working Group in 2005 and published the following year.1 They are designed to provide usable and uniform response criteria to allow comparison between results in clinical trials.

New criteria for stringent complete response (sCR) and very good partial response (VGPR) were proposed, and allowance for serum free light chain (SFLC) ratio measurement in cases of non-secretory myeloma is made.