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

Background: 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.

Methods: 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.

Results: 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.

Conclusion: 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.