Early minimal residual disease eradication in light chain amyloidosis generates deeper and faster cardiac response.

Minimal residual disease (MRD) is of growing interest in light chain (AL) amyloidosis and is associated with higher rates of cardiac response. A new graded cardiac response criteria has been proposed for better assessment of cardiac improvement. We evaluated MRD status in 63 patients with cardiac AL amyloidosis using next generation flow cytometry (sensitivity ≥ 1*10^-5) within four cycles after treatment initiation and cardiac response kinetics. All patients were treated with first-line proteasome inhibitor (100%) and predominantly bortezomib (87.3%). The overall early MRD negative rates were 33.3%. Patients who achieved early MRD negativity were less likely to harbor t(11;14) (21.1% vs 57.5%, P = 0.009). The MRD negative rates amongst patients in hematologic complete response were 66.7% (14/21), and in very good partial response 29.2% (7/24). Early MRD negativity was associated with a higher likelihood of achieving ≥ cardiac partial response (≥ CarPR) (66.7% vs 38.1%, P = 0.032) and ≥ cardiac very good partial response (≥ CarVGPR) (38.1% vs 11.9%, P = 0.023) throughout first-line therapy. The cumulative incidence curve of achieving ≥ CarPR (P = 0.034) and ≥ CarVGPR (P = 0.026) showed significant difference between early MRD negative and positive group. After a median follow-up time of 27.2 months, the median progression free survival was longer in early MRD negative group (not reached vs 31.3 months, P = 0.033). Early MRD eradication in cardiac AL amyloidosis generated deeper and faster cardiac organ response.