Long-Term Outcomes and Organ Responses with Daratumumab Therapy in Previously Treated Patients with AL Amyloidosis

• Published in: Blood 2019-11, Vol.134 (Supplement_1), p.1828-1828
• Main Authors: Chung, Alfred, Kaufman, Gregory P., Sidana, Surbhi, Eckhert, Erik, Schrier, Stanley, Arai, Sally, Lafayette, Richard, Witteles, Ronald, Liedtke, Michaela
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2019-122152

Introduction: AL amyloidosis involves deposition of abnormally folded light chains into a wide range of tissues causing end-organ dysfunction, including in the heart and kidney. Daratumumab, a CD38-targeted antibody, has recently demonstrated efficacy in producing hematologic responses in previously relapsed/refractory disease. However, data on long-term outcomes to daratumumab, including organ responses, are lacking. Here we present the largest retrospective study to date on patients with previously treated AL amyloidosis treated with daratumumab. Methods: We conducted a retrospective analysis of relapsed/refractory AL amyloidosis patients treated at Stanford University from January 2016 to January 2019. Patients treated with daratumumab, either as monotherapy with dexamethasone (DMT) or in combination with other plasma-cell directed therapies (DCT) were included. Hematologic and organ responses were assessed by consensus guidelines. Hematologic responses were based on the maximal change in the difference between involved and uninvolved free light chains (dFLC). For cardiac response, a >30% and >300 pg/mL decrease in NT-proBNP for patients with initial baseline NT-proBNP ≥650 pg/mL was considered a response. A graded cardiac response metric was also explored with partial response (PR) representing 30-59% reduction, very good partial response (VGPR) ≥60% reduction, and complete response (CR) NT-proBNP 30% decrease (by at least 0.5 g/day) in 24-hour urine protein without worsening in creatinine or creatinine clearance by more than 25% in patients with at least 0.5 g/day pretreatment was considered a response. A graded renal response metric was also explored with PR representing 30-59% reduction in proteinuria, VGPR ≥60%, and CR ≤ 200 mg per 24-hour period. Survival data was analyzed using the Kaplan-Meier method. All time-to-event outcomes, including survival and organ responses, were determined from initiation of daratumumab. Results: Eighty-four patients were identified with baseline characteristics at start of daratumumab shown in Table 1. Median duration of follow-up was 16 months. Two-year overall survival (OS) was 83% and median OS was not reached. Median time-to-next-treatment or death was 31 months. Sixty-seven out of 80 evaluable patients (84%) achieved a hematologic response, with 47 patients (59%) achieving a VGPR or better (Figure 1). Sixty-eight patients (81%) had cardiac involvement, an