Impact of light chain isotype on clinical features and outcomes in systemic AL amyloidosis.

We performed a retrospective cohort study in AL amyloidosis to investigate the impact of light chain (LC) isotype on clinical features in 112 consecutive patients. Patients with kappa LC isotype had a significantly higher difference in free light chain (dFLC) (median, 61.5 vs. 21.6 mg/dL, <i>p</i> = .02) and involved/uninvolved FLC ratio (median, 63.5 vs. 10.6, <i>p</i> &lt; .01) compared to lambda. Patients with lambda LC had a higher kidney involvement (64% vs. 38%, <i>p</i> = .02) but similar cardiac involvement rate (75% vs 72%; <i>p</i> = .81) as kappa. The hematologic ≥ VGPR rate after first-line therapy was similar (kappa [61%] vs lambda [68%]; <i>p</i> = .46). At a median follow-up of 43 months for surviving patients, the hazard ratio (kappa/lambda) for event-free survival (EFS) and overall survival (OS) was 0.76 (95% CI, 0.43-1.38; <i>p</i> = .37) and 0.49 (95% CI, 0.19-1.28; <i>p</i> = .14) respectively. Achievement of iFLC &lt; 2 mg/dL and dFLC &lt; 1 mg/dL was predictive of superior OS irrespective of LC isotype.