Histological Kidney Re-Evaluation after Daratumumab Monotherapy for AL Amyloidosis

Abstract

Background: AL amyloidosis is a systemic disorder characterized by extracellular deposition of characteristic fibrils that results in progressive multi-organ failure and premature death. Recently daratumumab has been demonstrating higher hematological and organ response rates when compared to the standard of care. We hereby report our long-term experience on the effects of daratumumab given alone on the deposition of amyloid as evaluated in repeat renal biopsy. Results: Six patients were enrolled. All patients had proteinuria that was associated with renal function impairment in four. After therapy with daratumumab, four patients achieved complete hematological response and two had partial hematological response at the end of treatment. With regard to renal response, four out of six patients achieved an organ response; one patient had fluctuating proteinuria levels and did not meet the needed criteria at the end of the treatment and the last patient, who was already in dialysis at the time of therapy initiation, remained on dialysis despite complete hematological and cardiac responses. A significant decrease in 24-h proteinuria from 7.9 g/24 h to 1.1 (p < 0.005) with stabilization or improvement of sCr (from 1.5 mg/dL to 1.2 mg/dL; p = 0.34) were observed. All patients underwent a repeat biopsy after 24 administrations of daratumumab. In five patients, the repeat biopsy showed unchanged features; while in one it showed an improvement. Conclusions: Our data, based on real life experience, show that daratumumab monotherapy can be an effective therapeutic option. It is capable not only of achieving a substantial rate of renal improvement in pre-treated and naïve patients, but also of limiting renal deposition