INTRODUCTION

Amyloidosis encompasses a group of disorders characterized by the extracellular deposition of misfolded, insoluble proteins across various organs and tissues. Among the 18 recognized forms of systemic amyloidosis, immunoglobulin light chain (AL) amyloidosis is the most prevalent [1]. In AL amyloidosis, the precursor proteins are unstable immunoglobulin light chains produced by a clone of plasma cells or, less frequently, by a lymphoplasmacytic or mantle cell lymphoma. Although cardiac involvement is the primary prognostic determinant in AL amyloidosis, kidney involvement, that is present in over 50% of cases at diagnosis, also significantly influences the clinical evolution and outcomes of affected patients [2, 3].

Management of AL amyloidosis primarily aims to eradicate the underlying plasma cell dyscrasia, with the goal of halting amyloid fibril production and limiting progressive organ damage. Accordingly, anti-plasma cell therapy (ACT), comprising systemic chemotherapy with or without autologous hematopoietic stem cell transplantation (ASCT), represents the cornerstone of disease management [4]. Although ASCT is considered first-line therapy, only ∼20% of patients are eligible due to age or comorbidities [4–7].

Hematologic response in AL amyloidosis is determined by monitoring serum free light chains (FLC) and/or monoclonal protein levels. Among affected organs, cardiac involvement represents the most powerful determinant of prognosis [8, 9]. This recognition has led to the development of organ-specific assessment strategies. In this context, cardiac response is routinely evaluated using NT-proBNP and troponins [10], while kidney response evaluation includes serum creatinine (SCr), estimated glomerular filtration rate (eGFR) and proteinuria levels. Traditionally, kidney response has been defined by a ≥50% reduction in proteinuria without deterioration in kidney function [11]. More recent studies have proposed alternative definitions incorporating deeper reductions in proteinuria (>75% or >95%) and early eGFR changes as potential dynamic markers of renal response [8, 9, 12].

Clinical guidelines recommend an initial evaluation of the disease response 3–6 months after initiating treatment [11]. Nonetheless, the optimal timing for evaluating kidney response and its prognostic significance is not well established.

In this study, we describe the time to achievement of kidney and hematologic response in a cohort of patients with kidney AL amyloidosis, and discuss the implications of these findings in the management of the disease.