MM-315 Light-Chain Amyloidosis Patients Treated With Daratumumab: A Single-Center Experience.

BACKGROUND: Light chain (AL) amyloidosis is an extreme form of systemic amyloidosis, causing organ dysfunction, mainly affecting the heart and kidneys. Daratumumab was the first monoclonal CD38 antibody approved for the treatment of AL amyloidosis. There are few real-world data about the use of daratumumab in patients with AL amyloidosis from Latin America.

OBJECTIVE: Describe the hematological and organ response in patients with AL amyloidosis treated with daratumumab.

PATIENTS AND METHODS: A retrospective cohort of patients with AL amyloidosis in a single center treated with daratumumab from January 2018 to April 2022. Daratumumab was administered intravenously with low-dose dexamethasone alone or in combination with cyclophosphamide, bortezomib, and dexamethasone (CyBorD). Doses were adjusted to reduce toxicities.

RESULTS: Twelve patients were included. The overall median age was 64 (IQR, 43-77) years old, eight (67%) were female. Five patients were newly diagnosed, while seven patients had relapsed or refractory disease. One patient died during the first cycle of daratumumab, and the remaining 11 patients completed a median of 11 (IQR, 2-30) cycles. Overall, ten (83%) patients presented a hematologic response, six (60%) presented a very good partial response or better after a median of 1.5 cycles of treatment. Median time-to-hematologic response was 1.5 months. Nine patients (75%) had cardiac involvement, three had IIIB and two patients had IIIC cardiac stage respectively. Four (44%) of evaluable patients achieved a cardiac response, with a median time to response of 8 months. Six patients (50%) had renal involvement, and two (33%) of evaluable patients achieved a renal response, with a median response time of 16 months. After a median follow-up of 21 months, one patient underwent a successful cardiac transplant and autologous stem cell transplantation (ASCT), while two other patients were in preparation for ASCT. Seven patients remained on daratumumab at the last follow-up. Two patients had infectious complications. There were no unexpected toxicities, and no grade III or IV adverse events, although more than half of our patients had advanced cardiac stage.

CONCLUSIONS: Daratumumab induces deep and rapid hematologic response in newly diagnosed and previously treated AL amyloidosis patients. Intravenous administration is tolerated, even in patients with advanced heart disease.