Landgren O, et al. - In this prospective cross-sectional cohort investigation, researchers longitudinally examined the changes of serum immune markers with stable vs progressive monoclonal gammopathy of undetermined significance (MGUS), given that multiple myeloma is consistently preceded by MGUS. They found that IgA isotype, 15 g/L or more monoclonal spike, skewed (<0.1 or >10) serum free light chains ratio, and severe immunoparesis (≥2 suppressed uninvolved immunoglobulins) were risk factors related to progressive MGUS in cross-sectional modeling. Skewed serum free light chains ratio and severe immunoparesis were identified as risk factors related to progressive light-chain MGUS. In longitudinal inquiry of participants with serial samples before progression, a high-risk MGUS before progression was detected in 23 of 43 participants (53%). Within 5 years, conversion from low-risk or intermediate-risk MGUS was reported in 16 of these 23 (70%) participants. For light-chain MGUS, similar findings were obtained.