Analysis of CD20 and PD-L1 levels on small extracellular vesicles (sEV) produced by DLBCL cells and EBV-transformed B cells, and potential role in T cell inhibition.

Increasing evidence supports a role for small extracellular vesicles (sEV, including exosomes) in Diffuse Large B-cell lymphoma (DLBCL) progression and resistance to treatment. CD20 and PD-L1 are found on DLBCL-derived sEV, but little is known about their patient-level heterogeneity. Moreover, the capacity of PD-L1+ sEV to modulate T cells needs to be clarified. Herein we analyzed sEV produced by human DLBCL cell lines and EBV-transformed B cell-lymphoblastoid cell lines (LCLs), a model allowing autologous T cell co-cultures. We determined CD20 and PD-L1 levels on plasma sEV from patient samples vs healthy volunteers (HV). sEV functional relevance was also investigated on CD4+ and CD8+ T cells. sEV derived from all cell lines showed an enrichment of CD20 and a high glycosylated PD-L1 expression when compared to cell lysates. High PD-L1 expression on LCL-derived sEV was associated with higher CD4+ and CD8+ T cell apoptosis. In patients, plasma sEV concentration was higher vs HV. Compared to sEV-CD20 level that seemed higher in patients, PD-L1 level in sEV was not different from those of HV. A high glycosylated PD-L1 level was shown in sEV from both patients and HV plasma samples, that was associated with the same inhibiting effect on activated T cells. We conclude that sEV derived from EBV-transformed B cells realize an immunosuppressive role that involved cell-cell interaction and probably at least PD-L1. Furthermore, our findings suggest the potential of circulating sEV as a source of biomarkers in DLBCL, notably to have information on immunotherapeutic target levels of parental tumor cells.

Analysis of a cohort of 279 patients with hairy-cell leukemia (HCL): 10 years of follow-up.

In total, 279 patients with hairy-cell leukemia (HCL) were analyzed, with a median follow-up of 10 years. Data were collected up to June 2018. We analyzed responses to treatment, relapses, survival, and the occurrence of second malignancies during follow-up. The median age was 59 years. In total, 208 patients (75%) were treated with purine analogs (PNAs), either cladribine (159) or pentosatin (49), as the first-line therapy. After a median follow-up of 127 months, the median overall survival was 27 years, and the median relapse-free survival (RFS) was 11 years. The cumulative 10-year relapse incidence was 39%. In patients receiving second-line therapy, the median RFS was 7 years. For the second-line therapy, using the same or another PNA was equivalent. We identified 68 second malignancies in 59 patients: 49 solid cancers and 19 hematological malignancies. The 10-year cumulative incidences of cancers, solid tumors, and hematological malignancies were 15%, 11%, and 5.0%, respectively, and the standardized incidence ratios were 2.22, 1.81, and 6.67, respectively. In multivariate analysis, PNA was not a risk factor for second malignancies. HCL patients have a good long-term prognosis. PNAs are the first-line treatment. HCL patients require long-term follow-up because of their relatively increased risk of second malignancies.

Prohibitin (PHB) expression is associated with aggressiveness in DLBCL and flavagline-mediated inhibition of cytoplasmic PHB functions induces anti-tumor effects.

BACKGROUND: Diffuse large B-cell lymphomas (DLBCLs) are aggressive lymphomas accounting for approximately a third of non-Hodgkin lymphomas. Prohibitin 1 (PHB1) and prohibitin 2 (PHB2) are scaffold proteins that promote mitochondria homeostasis and consequently cell survival, but biological functions of cytoplasmic PHBs remain largely unknown in DLBCL. METHODS: PHB expression was analyzed in 82 DLBCL biopsies and five DLBCL cell lines by immunohistochemistry (IHC) and Western blotting. Pharmacological inhibition of PHB using the synthetic flavagline FL3 was realized in vitro to gain insight PHB cellular functions. Effects of FL3 on DLBCL cell line viability, apoptosis, C-Raf-ERK-MNK-eIF4E signaling pathway and eIF4F complex formation and activity were evaluated by XTT assay, annexin V-FITC/PI dual staining and Western blotting respectively. Subcutaneous DLBCL xenograft model in SCID mice was also performed to determine in vivo FL3 effect. RESULTS: As in DLBCL cell lines, PHB1 and PHB2 were expressed in germinal center B-cell-like (GCB) and activated B-cell-like (ABC) subtypes. In patient samples, high PHB levels were associated with higher serum LDH (PHB1 and PHB2), IPIaa (PHB2), and Ki-67 (PHB2) expression. Higher PHB1 expression tends to be associated with shorter event-free survival (EFS) in patients, especially in male patients. FL3 induced apoptosis of DLBCL cell lines that was associated with inhibition of the ERK-MNK-eIF4E signaling pathway, including aggressive double/triple-hit DLBCL cell lines. This resulted in altered eIF4F complex formation and activity leading to a reduction of Bcl-2 and c-Myc expression levels. Moreover, FL3 strongly downregulated DLBCL cellular levels of Akt protein and AKT mRNA. FL3 antitumor activity was also confirmed in vivo in a murine xenograft model. CONCLUSION: Our data indicate that PHB overexpression is associated with markers of tumor aggressiveness in DLBCL, and that targeting PHBs may be a therapeutic option, notably in aggressive subtypes.

Anti-apoptotic role and clinical relevance of neurotrophins in diffuse large B-cell lymphomas.

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) is a fatal malignancy that needs to identify new targets for additional therapeutic options. This study aimed to clarify the clinical and biological significance of endogenous neurotrophin (nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF)) in DLBCL biopsy samples and cell lines. METHODS: We analysed expression of NGF, BDNF, and their receptors (Trk, p75(NTR)) in 51 biopsies and cell lines by immunohistochemistry, immunofluorescence, and western blotting. To investigate the biological role of BDNF/TrkB/p75(NTR) axis, effects of neurotrophin signalling inhibition were determined on tumour cell survival and vascular endothelial growth factor (VEGF) secretion. The pharmacological pan-Trk inhibitor K252a was used for in vitro and in vivo studies. RESULTS: A BDNF/TrkB axis was expressed in all biopsies, which was independent of the germinal centre B-cell (GCB)/non-GCB profile. p75(NTR), TrkB, and BDNF tumour scores were significantly correlated and high NGF expression was significantly associated with MUM1/IRF4, and the non-GCB subtype. Diffuse large B-cell lymphoma cell lines co-expressed neurotrophins and their receptors. The full-length TrkB receptor was found in all cell lines, which was also phosphorylated at Tyr-817. p75(NTR) was associated to Trk and not to its cell death co-receptor sortilin. In vitro, inhibition of neurotrophin signalling induced cell apoptosis. K252a caused cell apoptosis, decreased VEGF secretion, and potentiated rituximab effect, notably in less rituximab-sensitive cells. In vivo, K252a significantly reduced tumour growth and potentiated the effects of rituximab in a GCB-DLBCL xenograft model. CONCLUSIONS: This work argues for a pro-survival role of endogenous neurotrophins in DLBCLs and inhibition of Trk signalling might be a potential treatment strategy for rituximab resistant subgroups.

CD68-positive tumor-associated macrophages predict unfavorable treatment outcomes in classical Hodgkin lymphoma in correlation with interim fluorodeoxyglucose-positron emission tomography assessment.

Finding new prognostic factors to identify patients with Hodgkin lymphoma (HL) at risk of treatment resistance or relapse remains challenging in daily practice. We evaluated the relationship between CD68 expression, interim positron emission tomography (iPET) results and outcome in 158 patients with HL diagnosed from February 1995 to July 2011. Immunohistochemistry (anti-CD68) gave two groups: low with ≤25% positive cells (121 patients) and high with >25% (37 patients). Five-year overall survival was higher in the low group (88.4% vs. 63.2%, p=0.0151), as was progression-free survival (74.5% vs. 40.7%, p=0.0003). In 68 patients evaluable, iPET correlated with CD68: 13/52 patients (25%) in the low group had positive iPET as compared to 11/16 patients (68%) in the high group (p=0.0016). This study confirms the prognostic value of CD68 in HL. We found a correlation between CD68 and iPET suggesting potential for a better stratification.

Prognostic significance of BAD and AIF apoptotic pathways in diffuse large B-cell lymphoma.

BACKGROUND: To determine whether proapoptotic proteins were associated with clinicopathologic heterogeneity and influenced survival in patients with diffuse large B-cell lymphoma (DLBCL), we evaluated patterns of expression of the BCL-2 family member BAD, PP1alpha (the catalytic subunit of PP1 involved in activation of BAD), and apoptosis-inducing factor (AIF). PATIENTS AND METHODS: We retrospectively analyzed 46 patients all treated with standard chemotherapy ([CHOP] cyclophosphamide/doxorubicin/vincristine/prednisone-like); of these, 16 received rituximab. Immunohistochemical analyses were performed from biopsy samples of nodal DLBCL that were performed at initial diagnosis. Normal reactive lymph nodes were used as controls. RESULTS: BAD expression was found in 38 of 46 DLBCL cases and, though variable, was often strong. PP1alpha and AIF were detected in all tumors tested with a relative strong expression. Lower BAD expression was shown to be significantly associated with advanced clinical stages (Ann Arbor stage III + IV and International Prognostic Index intermediate-high to high; P = .006 and P = .0008, respectively). Moreover, BAD staining was positively correlated with BCL-2 (P = .022) and PP1alpha (P = .013) staining. Finally, high AIF expression proved to be predictive of a longer overall survival in non-rituximab-treated patients. CONCLUSION: Our study shows for the first time in DLBCL that differential BAD expression might play a role in the development of the disease, possibly reflecting its function as a tumor suppressor. Furthermore, our data highlight the interest in targeting BAD phosphatases and AIF-mediated mitochondrial apoptosis for new therapeutic strategies.