Supervisors info:
Ουρανία Τσιτσιλώνη, Καθηγήτρια Ανοσολογίας
Τομέας Φυσιολογίας Ζώων και Ανθρώπου
Τμήμα Βιολογίας, Σχολή Θετικών Επιστημών, ΕΚΠΑ
Summary:
Immunoglobulin light chain amyloidosis (AL) is caused by misfolded free light chains (FLCs) which are produced by a small and usually indolent malignant plasma cell clone. The amyloid fibrils deposit in various tissues and cause severe dysfunction of multiple organs such as kidneys, heart, liver or the peripheral nervous system (Dittrich et al., 2017). Novel therapies, such as the anti-CD38 monoclonal antibody Daratumumab are able to induce deeper hematological responses in patients with primary systemic amyloidosis (Sanchorawala et al., 2018). More recently, the value of minimum residual disease (MRD) has started to emerge as a prognostic marker in hematological and organic responses to AL amyloidosis. Several data correlate MRD negativity with improved cardiac response rates and improved progression free survival (PFS) even during a short follow-up period (Sidana et al., 2020). However, there is a need to develop biomarkers to assess MRD, as it burdens the function of major organs such as the heart and kidneys, even in patients that have achieved complete remission. The purpose of this project was to analyze the bone marrow (BM) microenvironment of patients with AL amyloidosis in association with the administration of Daratumumab, and the presence or absence of MRD. For this, BM samples from 25 patients with AL amyloidosis were collected during diagnosis, after first-line therapy and after consolidation therapy with Daratumumab. The samples were analyzed with the use of New Generation Flow cytometry (NGF) in order to perform an immunophenotypic assessment of the surface markers CD19, CD27, CD38, CD45, CD56, CD81, CD117, CD138 and intracellular κ and λ chains for the detection of MRD, based on the EuroFlow guidelines. At the same time we performed the identification and quantification of 17 BM haematopoietic populations. Daratumumab increased the rates of erythroblasts, T, CD27+ NK & NKT lymphocytes, B cell precursors, and mast cells, while it reduced the percentage of naive B lymphocytes in patients who remained MRD+ after administration of Daratumumab. Interestingly, there was an increasing trend in the rate of erythroblasts in patients who remained MRD+ compared to MRD- patients after therapy with Daratumumab. However, the presence/absence of MRD did not appear to affect the microenvironment of the BM, probably due to the low number of MRD- samples. In conclusion, we show that the EuroFlow method for the detection of MRD in AL amyloidosis permits the identification and quantification of 17 BM populations. At the same time, administration of Daratumumab significantly reduces the burden of disease in AL amyloidosis. Finally, we observed changes in the composition of the clonal population and the immunophenotype of clonal cells, and a statistically significant increase in the rate of erythroblasts, leading us to the conclusion that Daratumumab has a profound effect on the BM microenvironment.
Keywords:
AL amyloidosis, minimal residual disease, flow cytometry, plasma cell, daratumumab
