IMWG Partial Response

**Semantic type:** Intellectual Product

**Definition:** At least 50 percent reduction of serum M-protein plus reduction in 24 hour urinary M-protein by at least 90 percent or to less than 200 mg per 24 hour. If the serum and urine M-protein are unmeasurable, at least a 50 percent decrease in the difference between involved and uninvolved free light chain 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, at least a 50 percent reduction in plasma cells is required in place of M-protein, provided baseline bone marrow plasma-cell percentage was at least 30 percent. In addition to these criteria, if present at baseline, at least 50 percent reduction in the size (sum of products of diameters) of soft tissue plasmacytomas is also required.

**Synonyms:** - Partial Response