Renal outcomes in patients with AL amyloidosis: Prognostic factors, renal response and the impact of therapy

A staging system for patients with renal AL amyloidosis, based on eGFR (<50 ml/min/1.73 m² ) and proteinuria (≥5 g/day) at diagnosis, as well as criteria for renal progression (≥25% eGFR reduction) and response (≥30% reduction of proteinuria without renal progression) were recently proposed. We validated these criteria in a cohort of 125 patients with renal AL amyloidosis, mostly treated with bortezomib or lenalidomide. We confirmed the prognostic value of the renal staging system but also identified the limitations of renal progression criteria which are based only on eGFR reduction. We identified the ratio of 24h proteinuria to eGFR as a sensitive marker of renal risk which also accounts for changes in both proteinuria and eGFR: 24h proteinuria/eGFR ratio <30 (in mg/ml/min/1.73 m² ) was associated with a 2-year progression to dialysis rate of 0% compared to 9% for a ratio of 31-99 and 35% for a ratio ≥100 (P < .001). In landmark analysis, patients who achieved a reduction of this ratio by at least 25% or ≤100 (if initially >100) at 3 months had a 2-year progression to dialysis of 0% vs 24% for patients who either did not reduce to or still had a ratio >100 (P = .001); similar results were obtained by applying the same criteria at 6 months; thus, the evaluation of treatment effect on renal function may be identified early. Furthermore, primary bortezomib-based therapy was more effective than lenalidomide-based therapy, in terms of renal outcomes, especially in patients at intermediate renal risk, but without affecting overall survival.