Limited duration of dexamethasone in newly diagnosed AL amyloidosis: impact on response, toxicity, and survival

Background Systemic light chain amyloidosis (AL) is a life-threatening disease in which dexamethasone (Dex) is a core therapy but is limited by cumulative toxicity. The optimal duration of Dex, particularly in the era of daratumumab (Dara)-based regimens, is uncertain.Methods We retrospectively analyzed 216 newly diagnosed AL amyloidosis patients (2017–2023). Dex exposure was categorized as limited (≤3 months) or prolonged (>3 months) using restricted cubic spline-derived associations with hematologic response kinetics. Outcomes included hematologic and organ response, toxicity, and overall survival.Results Median Dex duration was 5.5 months and was similar by Dara use. Overall response rates exceeded 90% at 6 months in both Dex groups. Limited Dex was associated with higher rates of early deep hematologic response (VGPR or better 77.5 vs 56.5%, p = 0.001; CR 42.2 vs 19.4%, p < 0.001), reflecting faster response kinetics, while overall response rates were similar. Among patients receiving limited Dex, Dara was associated with higher 6-month CR rates (66.7 vs 30.4%, p < 0.001) and increased likelihood of achieving CR in multivariable analysis (HR 4.38, 95% CI 2.44-7.85; p < 0.001). Organ responses were similar between groups. Dex-related toxicities increased after 6 months, and hospitalization was associated with worse survival.Conclusions Limiting Dex exposure was associated with preserved efficacy and reduced toxicity. Prolonged Dex was associated with increased toxicity without improving overall hematologic or organ outcomes, supporting limited Dex duration in frontline AL amyloidosis therapy.