Serum free light chain level-based and non-fixed cycle daratumumab treatment strategy for patients with light chain amyloidosis

In recent years, daratumumab (DARA) has gained widespread use in the treatment of systemic light chain (AL) amyloidosis. In this study, we assessed the efficacy and safety of a DARA treatment strategy based on serum free light chain (sFLC) levels and non-fixed cycles. The study included 123 patients with Al amyloidosis who received DARA at our center between July 2020 and September 2023. All patients received the standard DARA treatment (16 mg/kg weekly for four weeks) during the first course. Subsequent treatments were adjusted based on sFLC levels and the physician's judgment. The results demonstrated an impressive overall hematologic response rate (ORR) of 94.3%, with a hematologic very good partial response (VGPR) and complete response (CR) rate of 84.5%. Median time to best hematologic response was 1 months. Cardiac and renal response rates were 39.3% and 60.3%, respectively. Thirty patients experienced grade 1/2 infusion-related reactions after the first infusion. The rate of grade 3/4 adverse events was 21%. The most common adverse events of grade 3 or 4 were pulmonary infection (6.5%), neutropenia and lymphocytopenia (5.7%), elevated transaminases (1.6%), acute kidney injury (1.6%). After a median follow-up of 13 months (range 1-38), The 1-year OS and PFS estimates were 96.5% and 84.4%, respectively. These findings indicate that the sFLC levels based and non-fixed cycle DARA strategy is an efficacious and safe treatment strategy in both newly diagnosed and relapsed/refractory AL amyloidosis.