Daratumumab, a monoclonal CD38 antibody, is approved in the treatment of myeloma, but its efficacy and safety in light-chain (AL) amyloidosis has not been formally studied. This prospective phase 2 trial of daratumumab monotherapy for the treatment of AL amyloidosis was designed to determine the safety, tolerability, and hematologic and clinical response. Daratumumab 16 mg/kg was administered by IV infusion once weekly for weeks 1 to 8, every 2 weeks for weeks 9 to 24, and every 4 weeks thereafter until progression or unacceptable toxicity, for up to 24 months. Twenty-two patients with previously treated AL amyloidosis were enrolled. The majority of the patients had received high-dose melphalan and stem cell transplantation and/or treatment with a proteasome inhibitor. The median time between prior therapy and trial enrollment was 9 months (range, 1-180 months). No grade 3-4 infusion-related reactions occurred. The most common grade ≥3 adverse events included respiratory infections (n = 4; 18%) and atrial fibrillation (n = 4, 18%). Hematologic complete and very-good-partial response occurred in 86% of patients. The median time to first and best hematologic response was 4 weeks and 3 months, respectively. Renal response occurred in 10 of 15 patients (67%) with renal involvement and cardiac response occurred in 7 of 14 patients (50%) with cardiac involvement. In summary, daratumumab is well tolerated in patients with relapsed AL amyloidosis and leads to rapid and deep hematologic responses and organ responses. This trial was registered at www.clinicaltrials.gov as #NCT02841033.

The depth of hematologic response has been shown to correlate with survival and organ responses for patients with light chain (AL) amyloidosis. We conducted a prospective trial of 2 cycles of induction with bortezomib and dexamethasone on a twice a week schedule followed by conditioning with bortezomib and high-dose melphalan (HDM) and autologous stem cell transplantation (SCT). The objectives were hematologic responses, tolerability, and survival. Thirty-five patients were enrolled from 2010 to 2013. Of these, 30 proceeded with SCT, whereas 5 did not because of clinical deterioration during induction (n = 3) or complications after stem cell collection (n = 2). Two patients developed features of an autologous graft-versus-host disease-like syndrome post-SCT, which responded to steroids; no other unusual complications were seen. Treatment-related mortality occurred in 8.5% (3/35). Hematologic responses were achieved by 100% of the 27 assessable patients (63% complete response, 37% very good partial response [VGPR]) who completed the planned treatment. By intention-to-treat, hematologic responses occurred in 77% of patients (49% complete response, 29% VGPR). With a median follow-up of 36 months, the median overall survival and progression-free survival were not reached. In conclusion, incorporating bortezomib into induction and conditioning yielded a high rate of hematologic responses after HDM/SCT in patients with AL amyloidosis.

The kidney is the most common organ affected by immunoglobulin light-chain (AL) amyloidosis and monoclonal immunoglobulin deposition disease (MIDD), often leading to end-stage renal disease (ESRD). High-dose melphalan and stem cell transplantation (HDM/SCT) is effective for selected patients with AL amyloidosis, with high rates of complete hematologic response and potential for improved organ dysfunction. Data on tolerability and response to HDM/SCT in patients with ESRD due to AL amyloidosis and MIDD are limited. We analyzed data on toxicity, efficacy, and hematologic and renal response of HDM/SCT in 32 patients with AL amyloidosis and 4 patients with MIDD who were dialysis-dependent for ESRD treated at Boston Medical Center between 1994 and 2016. The most common grade 3/4 nonhematologic toxicities were infections (75%), metabolic abnormalities (56%), mucositis (42%), constitutional symptoms (39%), pulmonary complications (39%), and diarrhea (28%). Treatment related mortality (defined as death within 100 days of SCT) occurred in 8% (3 of 36). A complete hematologic response was achieved in 70% of evaluable patients (19 of 27) at 1 year after HDM/SCT. In the entire cohort, median overall survival (OS) after HDM/SCT was 5.8 years; median OS was 1 year for those who did not achieve a complete hematologic response and 8 years for those who did achieve a complete hematologic response. Twelve patients (33%) underwent kidney transplantation after successful treatment with HDM/SCT at a median of 2.4 years after SCT. HDM/SCT is safe and effective in inducing hematologic complete responses and prolonging survival in patients with ESRD from AL amyloidosis and MIDD. Achievement of a durable hematologic response can make these patients possible candidates for renal transplantation.

Daratumumab is a human IgG1k monoclonal antibody targeting the CD38 surface antigen on plasma cells with proven efficacy in multiple myeloma. While biology of clonal plasma cells in AL amyloidosis is distinct from myeloma, clonal plasma cells in AL amyloidosis express surface CD38, providing a rationale for using daratumumab. Infusion-related reactions (IR) of 48% were reported in patients who had daratumumab as monotherapy for relapsed multiple myeloma. Therefore, we designed a clinical trial to study tolerability of daratumumab in those with relapsed AL amyloidosis (clinicaltrials.gov identifier: NCT02841033). The primary objective was to determine the safety and tolerability of infusion of daratumumab, with respect to IR. The secondary objectives were to assess hematologic response, clinical response and time to next treatment. Accrual began in April 2017. Patients with AL amyloidosis after ≥1 prior therapy, and involvement of at least 1 vital organ , eGFR of >20 mL/min, AST/ALT < 3xULN, NT-proBNP ≤8500 pg/mL, LVEF ≥30%, FEV1 ≥50% in patients with COPD or chronic smokers, and ECOG performance status of <3, received daratumumab at 16 mg/kg IV infusion weekly for weeks 1-8, followed by every 2 weeks for weeks 9-24 and every 4 weeks thereafter until progression or unacceptable toxicity, for up to 24 months. The first infusion of daratumumab was given in 1000 mL, the second infusion in 500 mL if no grade 1 or greater reactions occurred, and subsequent doses were administered in 500 mL of saline. All patients received acetaminophen, diphenhydramine, loratadine, famotidine, montelukast and methylprednisolone (100 mg for first 2 infusions and 60 mg thereafter) 30-60 mins prior to infusion. Ondansetron was added after development of grade 1 nausea/vomiting in the first 2 patients. Diphenhydramine, famotidine and methylprednisolone (40 mg) were also administered 2 hrs after start of infusion during the first 2 infusions even if there was no reaction. Methylprednisolone 20 mg (or its equivalent) and montelukast were given 24 and 48 hrs after start of infusion for the first 2 infusions and then it was optional. All patients received prophylaxis with acyclovir. At data cut-off (July 1, 2018) 24 patients were screened and 21 were enrolled. The median age was 65 (range, 42-84), and the median of prior therapies was 2 (range, 1-6): 14 (58.3%) had received SCT, 9 (37.5%) immunomodulatory agents, and 16 (66.6%) proteasome inhibitors. Eleven (52.3%) patients were refractory to prior therapy and the median time from last therapy was 9 months (range, 1-180). The median time from diagnosis to enrollment was 57 months. The median number of organ systems involved was 2 (range, 1-5): 11 (52.3%) had involvement of ≥2 organ systems, 18 (85.7%) had cardiac biomarker stage II or III disease. Median NT-proBNP level was 1346 pg/mL (range, 32-3962) and urine protein excretion was 0.4 g/24 h (range, 0-10.1), while median dFLC was 87.8 mg/L (range, 2.9-328.4). Now, 18 patients are on study and 375 infusions have been completed. The median of infusions received per patient is 19 (range, 3-27). Two patients were removed after developing progression of plasma cell dyscrasia after 2 and 9 cycles and 1 patient was removed by patient choice after 8 cycles. No patient experienced a grade 3-4 IR. Four (19%) patients experienced grade 1 nausea and vomiting during first infusion, which resolved after an antiemetic. The median time of first infusion was 7 hrs and 2nd infusion was 4 hrs 29 mins. Grade 3/4 adverse events were noted in 16 (76%) patients. Respiratory illnesses were experienced by 14 (66.6%), 3 (14%) of these were grade 3 events (Influenza A, Rhino/Enteroviral infection, PCP). Six (28.5%) patients were noted to be iron deficient and required parenteral iron infusion. Hematologic responses were rapid as shown in figure. Hematologic CR and VGPR were achieved by 84.2% (16/19), 85.7% (12/14) and 100% (6/6) patients at 3 months, 6 months and 12 months respectively. Renal response was evident in 37.5% (3/8) and cardiac response was evident in 40% (4/10) at 6 months following initiation of treatment. Daratumumab infusion is well tolerated in patients with relapsed AL amyloidosis when administered with appropriate supportive care. Infusion-related reactions were minimal and not comparable to reported incidence in myeloma. A rapid hematologic response after 1 dose of daratumumab in patients with AL amyloidosis is seen. Figure. Figure. Disclosures Sloan: Stemline Therapeutics: Consultancy.

Hematologic complete response (hemCR) in AL amyloidosis requires absence of monoclonal protein by immunofixation electrophoreses (IFE) and normal serum free light chain ratio (FLCR). Recent literature suggests that an involved free light chain (iFLC) <20 mg/L or difference in free light chains (dFLC) <10 mg/L may more accurately predict outcomes after treatment. We evaluated overall survival in 340 patients treated with high-dose melphalan and stem cell transplantation (SCT). Of 305 patients evaluable 6 months after SCT, 90 (30%) achieved hemCR, 132 (43%) dFLC <10 mg/L, 118 (39%) iFLC <20 mg/L, and 176 (58%) normal FLCR. Of 215 patients without hemCR, 65 (30%) had dFLC <10 mg/L and 86 (40%) had normal FLCR. Overall survival (OS) in those achieving dFLC <10 mg/L or normal FLCR without hemCR was inferior to those achieving hemCR (p = 0.013 and p = 0.001). OS was not significantly different in patients achieving iFLC <20 mg/L without hemCR compared with hemCR (p = 0.243). Of those with hemCR, OS was not significantly improved if dFLC <10 mg/L was also achieved (p = 0.852), but OS was improved for those with hemCR who also attained iFLC <20 mg/L (p = 0.009). Multivariate analysis demonstrated absence of monoclonal protein in IFE and iFLC <20 mg/L as independent predictors of survival. Attainment of hemCR remains a treatment goal, although achieving iFLC <20 mg/L may also predict improved OS.

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In immunoglobulin light-chain (AL) amyloidosis, the depth of hematologic response to treatment is associated with improved survival and organ responses. We conducted a clinical trial using bortezomib in induction and in conditioning with melphalan before stem cell transplantation (SCT) for AL amyloidosis. The results of this clinical trial with a median follow-up of 36 months have been reported previously. Here we report the long-term results of this clinical trial with a median follow-up of 77 months. We describe survival, durability of hematologic and organ responses, and relapse rates. Thirty-five patients were enrolled between 2010 and 2013. Hematologic complete response and very good partial response (VGPR) were noted in 100% (27 of 27) of the evaluable patients at 6 months post-SCT. Four patients (15%) had hematologic relapse at a median of 42 months, and 1 patient (3.7%) had organ progression despite maintaining a VGPR at 37 months. The median overall survival and progression-free survival have not yet been reached at the time of this report. Renal and cardiac responses occurred in 65% and 88%, respectively, at 5 years post-SCT. The median time to renal and cardiac response was 12 months and 6 months, respectively. In conclusion, incorporating bortezomib into induction and conditioning yielded durable hematologic responses of AL amyloidosis, with corresponding organ responses and prolonged survival.