Outcomes of Kidney Transplantation in AL Amyloidosis

Amyloid light chain (AL) amyloidosis is a systemic disease affecting multiple organs, including the kidney, heart, gastrointestinal tract, and nerves. Kidney involvement is common and seen in ~70% of patients with newly diagnosed AL amyloidosis. Proteinuria >5 g/day and estimated glomerular filtration rate <50 mL/min at the time of diagnosis predict 60%–85% progression to end stage kidney disease (ESKD) in 3 years (1). The survival of patients with AL amyloidosis improved significantly over the past several decades, owing to advancements of treatment options with plasma cell-targeted therapies and hematopoietic stem cell transplant (HSCT) (2). Overall survival (OS) at 10 years is 95% for patients with AL amyloidosis who achieve hematological complete remission (CR) with high-dose melphalan and HSCT (3). Despite the encouraging survival data, kidney transplantation is rarely used for patients with ESKD due to AL amyloidosis. According to the United Network for Organ Sharing (UNOS) database, only 30–40 cases out of a total of ~22,000 kidney transplants per year were performed for patients with all types of amyloidosis (4).

Recently, three key observational studies updated data on the outcomes of kidney transplantation in AL amyloidosis. Angel-Korman et al. (5) reported a single-center cohort study from the Boston University Amyloidosis Center (n = 49); the median OS (mOS) and allograft survival after kidney transplant were 10.5 and 8.3 years, respectively. Hematological CR or very good partial response (VGPR) was associated with longer OS and less recurrence rate. Law et al. (6) studied data from the UK National Amyloidosis Centre (n = 51); OS and allograft survival of kidney transplant recipients with AL amyloidosis were not different from kidney transplant recipients due to diabetes. Cardiac involvement (interventricular septal thickness <12 mm) was associated with worse OS, whereas hematological CR was associated with better OS. Heybeli et al. (7), from the Mayo Clinic (n = 60), reported their experience of excellent mOS of 10.3 years after kidney transplant. Interestingly, even patients who were treatment naive before kidney transplant achieved CR with high-dose melphalan and autologous HSCT after kidney transplant. In addition, UNOS/Organ Procurement & Transplantation Network (OPTN) analyses repeatedly showed that OS and kidney allograft survival for AL amyloidosis patients are similar to kidney transplant recipients due to diabetes, especially with deceased kidney transplant (4, 8).

Is it time to consider kidney transplant as an option for ESKD management for patients with AL amyloidosis? When evaluating transplant candidacy, we should consider both utility (improvement of survival and quality of life) and justice (equitable allocation of scarce resource of donated organs). Data from the cohort studies and UNOS database analyses are promising for AL amyloidosis patients, as OS and allograft survival are similar to those who received kidney transplant due to diabetes and are better than patients remaining on dialysis. It is now reasonable to offer kidney transplant for carefully selected groups of AL amyloidosis patients with hematological CR and/or VGPR. Larger, multi-center studies are needed.

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