Multiple Myeloma Response Criteria

Myeloma Response Calculator
M-protein negative on immunofixation (serum & urine)
Normal free light chain (FLC) ratio
Bone marrow plasma cells absent or ≤5%
Soft tissue plasmacytomas absent
≥90% reduction in serum M-protein
Urine M-protein <100 mg/24h or ≥90% reduction
≥50% reduction in serum M-protein
≥90% reduction or <200 mg/24h urine M-protein
25–49% reduction in serum M-protein
Evidence of progressive disease
Response: Stable Disease (SD)
Stable Disease (SD)
Does not meet criteria for sCR, CR, VGPR, PR, MR, or PD.
Predicts disease response in multiple myeloma, from the International Myeloma Working Group (IMWG).

Why Use

Standardizes response assessment for clinical and research settings, enabling uniform reporting and direct comparisons between treatment strategies. Unlike similar response criteria, this tool incorporates FLC response and includes several additional response categories.

When to Use

Used at various time points during multiple myeloma (MM) therapy to evaluate treatment response and progression. Primarily designed for clinical trials.

Formula

Selection of the appropriate criteria: Criteria Response category Negative immunofixation of serum and urine AND disappearance of any soft tissue plasmacytomas AND <5% plasma cells in bone marrow Complete response (CR) CR as defined above plus normal FLC ratio (0.26-1.65) AND absence of clonal cells in bone marrow by immunohistochemistry or immunofluorescence Stringent complete response (sCR) Serum and urine M component detectable by immunofixation but not on electrophoresis OR ≥90% reduction in serum M component plus urine M component <100 mg per 24 hrs Very good partial response (VGPR) ≥50% reduction of serum M protein and reduction in 24 hr urinary M protein by ≥90% or to <200 mg per 24 hrs If serum and urine M protein are unmeasurable, ≥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 Partial response (PR) Not meeting criteria for CR, VGPR, PR, or progressive disease Stable disease (SD) 25% increase from lowest response value in ≥1 of the following: Serum M component (absolute increase must be ≥0.5 g/100 mL) Urine M component (absolute increase must be ≥200 mg per 24 hrs) Only in patients without measurable serum and urine M protein levels: difference between involved and uninvolved FLC levels (absolute increase must be >100 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 must be >11.5 mg/dL) that can be attributed solely to the plasma cell proliferative disorder Progressive disease (PD)

Pearls / Pitfalls

This tool is based on the 2006 version of the criteria; clinical relapse and relapse from complete response (CR) categories are not included. The criteria were updated in 2016 to reflect improved response rates with newer MM treatments, incorporating flow cytometry and gene sequencing to detect residual tumor cells in the bone marrow, as well as imaging to identify residual disease outside of the bone marrow (minimal residual disease negativity). The original criteria relied on serum, urine, and bone marrow assessments, which are now considered less sensitive compared to modern techniques. Testing must be confirmed on 2 consecutive assessments before initiating new therapy; bone marrow assessments do not require confirmation. Confirmatory testing can occur at any time following the first test, provided no new therapy has been started.

Advice

Results are primarily used in clinical trials to monitor treatment response. While no specific treatment recommendations are directly tied to results, response assessment can help determine whether a patient is meeting treatment goals and inform potential therapy adjustments.

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