Amyloid : the international journal of experimental and clinical investigation : the official journal of the International Society of Amyloidosis
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Daratumumab has major and rapid activity in AL amyloidosis with favourable toxicity. We used as a consolidation a short course of daratumumab in 25 patients with AL amyloidosis or light chain deposition disease (LCDD), who had not achieved a haematologic complete response (hemCR) after standard therapy with bortezomib, cyclophosphamide and dexamethasone (VCD). We evaluated minimal residual disease (MRD) and changes in the bone marrow (BM) microenvironment before and after consolidation using next generation flow cytometry (NGF). ⋯ In the BM, we observed significant changes in B-cell precursors, naïve B-cells, T-cells, CD27+ NK & NKT cells, mast cells and erythroblasts. After a median follow-up of 25 months, none of the patients in hemCR has relapsed and all have achieved an organ response; a haematologic relapse occurred in 6/17 patients that did not achieve hemCR. In conclusion, consolidation with a short course of daratumumab can improve depth of response in patients with AL amyloidosis or LCDD and significantly affects BM environment.
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Several studies recently showed that ex vivo fibrils from patient or animal tissue were structurally different from in vitro formed fibrils from the same polypeptide chain. Analysis of serum amyloid A (SAA) and Aβ-derived amyloid fibrils additionally revealed that ex vivo fibrils were more protease stable than in vitro fibrils. ⋯ We here show, for more than twenty different fibril samples, that ex vivo fibrils are more protease stable than in vitro fibrils. These data support the idea of a proteolytic selection of pathogenic amyloid fibril morphologies and help to explain why only few amino acid sequences lead to amyloid diseases, although many, if not all, polypeptide chains can form amyloid fibrils in vitro.