[Daratumumab for the treatment of primary systemic amyloidosis: a multicenter retrospective analysis]

Objective: To analyze the efficacy and safety of Daratumumab for the treatment of primary AL light chain systemic amyloidosis. Methods: Twenty one patients who were diagnosed as primary AL light chain systemic amyloidosis and treated with Daratumumab from 7 centers were retrospectively analyzed. Daratumumab was administrated as first line therapy in seven patients and 14 patients with relapsed settings. Hematological response, safety and survival were analyzed. Results: All 7 patients achieved very good partial response (VGPR) or better with first-line application of daratumumab. Three patients died, and the other four achieved organ remission. Among 14 relapsed patients, 2 patients had a difference of free light chain (dFLC) less than 20 mg/L before treatment, and 9 with a dFLC of more than 50 mg/L. All patients reached partial response (PR) or better, including 4 patients with complete response (CR), 3 with VGPR and 2 with PR. The response rate was 100% in 3 patients with dFLC 20-50 mg/L at baseline. The organ remission rate was 50% in patients with heart involvement and 58.3% in patients with kidney impairment. The overall median follow-up period was 5.3 months, and 11 months in surviving patients. One patient died of severe infection and disseminated intravascular coagulation (DIC) with stable amyloidosis. One patient switched to other regimens because dFLC elevated but did not fulfill progressive disease after 2 year application. As to safety, no grade 3/4 infusion reaction developed, and grade 1 infusion reaction occurred in 3 cases during the first infusion. Lymphocytopenia was seen in 75% patients including grade 3 or more in 30% patients. Conclusion: Daratumumab is effective to eliminate serum free light chain in both newly diagnosed and relapsed patients with systemic amyloidosis.