Abstract
BACKGROUND: Lenalidomide is an immunomodulatory agent used to treat plasma cell dyscrasias. We previously observed worsening of kidney function in a high proportion of patients with AL amyloidosis during lenalidomide treatment. The objective of this study is to characterize alterations in kidney function among patients with AL amyloidosis undergoing treatment with lenalidomide. METHODS: This is a secondary analysis of an ongoing clinical trial at a single referral centre. Forty-one patients with AL amyloidosis received lenalidomide with or without dexamethasone in monthly cycles. Kidney dysfunction was defined as ≥ 50% increase in serum creatinine. Severe kidney dysfunction was defined as ≥ 100% increase in serum creatinine. Recovery of renal function was defined as a return of serum creatinine to within 25% of the pre-treatment value or discontinuation of dialysis. RESULTS: Twenty-seven of 41 patients (66%) developed kidney dysfunction during lenalidomide treatment. The kidney dysfunction was severe in 13 of these patients (32%); four of whom required initiation of dialysis (10%). The median time to kidney dysfunction after starting lenalidomide was 44 days (interquartile range 15-108 days). Four of eight patients without underlying renal amyloidosis developed kidney dysfunction. Patients with severe kidney dysfunction were older and had a higher frequency of underlying renal amyloidosis, greater urinary protein excretion, and lower serum albumin. Recovery of renal function occurred in 12 patients (44%). CONCLUSIONS: Among patients with AL amyloidosis, worsening of kidney function occurs frequently during lenalidomide treatment. While a causal role of the drug has not been established, our findings suggest that kidney function should be monitored closely during treatment with this drug.