Higher Expression of CD44 in De Novo Diffuse Large B-cell Lymphoma Than in Richter Syndrome: USCAP 2022 Abstracts: Hematopathology (851-976)

Background: A subset of patients with chronic lymphocytic leukemia will experience transformation into Richter syndrome (RS), usually a diffuse large B–cell lymphoma (DLBCL). Clonal relationship based on IGHV analysis can determine a true RStransformation. Separating de novo DLBCL and RS is essential because novo DLBCL have a significantly better prognosis. The aim of this study is to find differentially expressed proteins in RS and de novo DLBCL.Design: The study comprised a total of 44 samples, specifically 18 RS and 26 de novo DLBCL of the non-GCB type. Among the RS, 8 were clonally related, 2 were clonally unrelated and for 8 no information was available regarding the clonal relationship. Initial proteomic screening analysis was processed through liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Among this 44 samples, 20 (10 RS and 10 de novo DLBCL) were analyzed by immunohistochemistry in order to evaluate the expression of CD44 and PKC-β. H-score was calculated with the semi quantitative evaluation of percentage of positive PKC-β cells multiplied by the weighted intensity of stain. All statistical analyses were performed using Student’s t-test. A p < 0.05 was considered statistically significant.Results: LC-MS/MS proteomic study identified a panel of proteins differentially expressed between RS and de novo DLBCLs (FDR<0.05), including CD44 (which was comparatively underexpressed in RS) and PKC-β (which was comparatively overexpressed in RS). The immunohistochemical study confirmed that CD44 expression is significantly higher in de novo DLBCL than in RS (p<0.002). PKC-β is also overexpressed in RS, but the difference is not significant.Conclusions: RS has a very poor prognosis and should not be confused with de novo DLBCL. This study demonstrated the interest of CD44 to immunophenotically distinguish RS from de novo DLBCL

High level of apoptosis and low AKT activation in mass screening as opposed to standard neuroblastoma

AIMS: Neuroblastoma is a paediatric solid tumour with a poor outcome except in children <1 year old. Based on catecholamine urinary excretion, mass screening (MS) programmes have been organized but failed to decrease the mortality of this tumour. To test the hypotheses of a spontaneous maturation/differentiation or regression, the levels of poly (ADP-ribose) polymerase (PARP)-1, an early apoptosis marker, of PhosphoAKT, a major apoptosis inhibitor, and of maturation/differentiation were compared in standard and in MS neuroblastomas. METHODS AND RESULTS: We performed a case-control study of 55 primary tumours and 21 metastases of MS neuroblastomas. Matched controls were standard unscreened neuroblastomas and were paired according to age, stage, and MYCN amplification. The tumours were included in tissue microarrays. Immunohistochemical staining was performed using antibodies against, AKT, phosphoAKT, TRKB and PARP-1. The expression of PARP-1 and that of phosphoAKT were significantly higher in standard than in MS neuroblastomas independently of age and stage of the tumour. PhosphoAKT and PARP-1 expression was significantly correlated in both tumours. CONCLUSIONS: These data suggest that the better prognosis of patients with MS neuroblastomas compared with classical neuroblastomas was secondary to spontaneous tumour regression mediated by higher levels of apoptosis associated with low activation of AKT