Table 3.

Definitions of disease relapse

Disease progression

Increase of 25% from lowest response value in any of the following

Serum M-component (absolute increase must be ≥0.5 g/dL) and/or

Urine M-component (absolute increase must be ≥200 mg/24 h) and/or

In patients without measurable serum or urine M protein levels:

Difference between involved and uninvolved free light chain values (absolute increase must be >10 mg/dL)

In patients without measurable serum, urine M protein, or free light chain values, bone marrow plasma cell percentage (absolute percentage must be ≥10%)

Definite development of new bone lesions or soft tissue plasmacytomas or definite increase in size of existing bone lesions or soft tissue plasmacytomas

Development of hypercalcemia (corrected serum calcium >11.5 mg/dL) that can be attributed solely to the plasma cell proliferative disorder

Significant paraprotein relapse

Doubling of the M-component in 2 consecutive measurements separated ≤2 months

Increase in the absolute level of serum M protein by ≥1 g/dL

Increase in urine M protein by ≥500 mg/24 h

Increase in involved free light chain level by ≥20 mg/dL (plus an abnormal FLC ratio) in 2 consecutive measurements separated by ≤2 months

Adapted from Rajkumar et al.⁶⁵