Maximum change in paraprotein from baseline. In addition to reduction in paraprotein, International Myeloma Working Group criteria require (1) results from 2 consecutive tests demonstrating the necessary percent reduction in paraprotein, (2) reduction in paraprotein in both serum and urine, if measurable disease was determined by both serum and urine paraprotein, and (3) a ≥50% reduction in the size of soft tissue plasmacytomas, if these were present at baseline. Thus, ≥50% and ≥90% reduction in paraprotein do not correlate directly with PR and VGPR, respectively.