Comparative genomic expression signatures of signal transduction pathways and targets in paediatric Burkitt lymphoma: a Children's Oncology Group report

Paediatric Burkitt lymphoma patient-derived xenografts capture disease characteristics over time and are a model for therapy

Burkitt lymphoma (BL) accounts for almost two-thirds of all B-cell non-Hodgkin lymphoma (B-NHL) in children and adolescents and is characterised by a MYC translocation and rapid cell turnover. Intensive chemotherapeutic regimens have been developed in recent decades, including the lymphomes malins B (LMB) protocol, which have resulted in a survival rate in excess of 90%. Recent clinical trials have focused on immunochemotherapy, with the addition of rituximab to chemotherapeutic backbones, showing encouraging results. Despite these advances, relapse and refractory disease occurs in up to 10% of patients and salvage options for these carry a dismal prognosis. Efforts to better understand the molecular and functional characteristics driving relapse and refractory disease may help improve this prognosis. This study has established a paediatric BL patient-derived xenograft (PDX) resource which captures and maintains tumour heterogeneity, may be used to better characterise tumours and identify cell populations responsible for therapy resistance.

Identification of clinical molecular targets for childhood Burkitt lymphoma

Burkitt lymphoma (BL) is a malignant tumor in children. Although BL is generally curable, early relapse and refractoriness may occur. Some molecular indicators have been recently suggested for BL diagnosis, but large heterogeneity still exists. This study aimed at providing clinical molecular targets and methods that may help improve diagnosis and treatment of childhood BL. Only children patients were included in the study, and targeted gene sequencing was conducted to identify tumor specific mutations. The mRNA and protein level expression of potential target genes were measured by real-time PCR and immunohistochemistry. The relationship between BL specific gene mutation and differential expression with clinical features was analyzed. The results showed that i) detailed analysis of c-MYC/BCL2/BCL6 gene loci alteration and gene expression would help in accurate diagnosis and treatment determination of childhood BL; ii) loss-of-function mutations in SOCS1 or CIITA gene might be used as malignant markers for BL diagnosis and prognosis; iii) specific mutations of CD79A, MYD88, KLF2, DNMT3A and NFKBIE genes often concurrently existed in BL and showed association with benign clinical outcomes; iv) the high expression of MYC, TCF3 and loss-of-function ID3 genes in tumor may be potential therapeutic targets and could be used for treatment monitoring; and v) four MYC-translocation negative cases were re-defined as high-grade B-cell lymphoma-not otherwise specified (HGBL-NOS) but showed similar clinical outcomes and molecular features to other BL cases in the study, suggesting more studies needed to explore the molecular mechanisms and clinical significance of this provisional tumor entity.

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Detailed analysis of c-MYC/BCL2/BCL6 gene alteration and expression may help in accurate diagnosis and treatment;

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The MYC-translocation negative cases (HGBL-NOS) showed similar clinical outcomes and molecular features to other cases;

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Loss-of-function mutations of SOCS1 or CIITA gene could be used as malignant markers for diagnosis and prognosis;

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Concurrent mutations in CD79A, MYD88, KLF2, DNMT3A and NFKBIE genes associated with benign clinical outcomes;

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High expression of MYC, TCF3 and loss-of-function ID3 gene in tumor may be potential therapeutic targets.

Obinutuzumab (GA101) vs. rituximab significantly enhances cell death, antibody-dependent cytotoxicity and improves overall survival against CD20+ primary mediastinal B-cell lymphoma (PMBL) in a xenograft NOD-scid IL2Rgnull (NSG) mouse model: a potential targeted agent in the treatment of PMBL

Primary mediastinal large B-cell lymphoma (PMBL), a distinct mature B-cell lymphoma, expresses CD20 and has recently been successfully treated with the combination of a type I anti-CD20 monoclonal antibody, rituximab, with multiple combination chemotherapy regimens. Obinutuzumab is a glycoengineered type II anti-CD20 monoclonal antibody (mAb), recognizing a unique CD20 extracellular membrane epitope with enhanced antibody dependent cellular cytotoxicity (ADCC) vs rituximab. We hypothesize that obinutuzumab vs rituximab will significantly enhance in-vitro and in-vivo cytotoxicity against PMBL. PMBL cells were treated with equal dose of obinutuzumab and rituximab for 24 hours (1–100 μg/ml). ADCC were performed with ex-vivo expanded natural killer cells at 10:1 E: T ratio. Mice were xenografted with intravenous injections of luciferase expressing Karpas1106P cells and treated every 7 days for 8 weeks. Tumor burden was monitored by IVIS spectrum system. Compared with rituximab, obinutuzumab significantly inhibited PMBL cell proliferation (p = 0.01), promoted apoptosis (p = 0.05) and enhanced ADCC (p = 0.0002) against PMBL. Similarly, in PMBL xenografted NOD scid gamma mice, obinutuzumab significantly enhanced survival than rituximab when treated with equal doses (p = 0.05). Taken together our results suggest that obinutuzumab significantly enhanced natural killer cytotoxicity, reduced PMBL proliferation and prolonged the overall survival in humanized PMBL xenografted NOD scid gamma mice.

A Single Gene Expression Set Derived from Artificial Intelligence Predicted the Prognosis of Several Lymphoma Subtypes; and High Immunohistochemical Expression of TNFAIP8 Associated with Poor Prognosis in Diffuse Large B-Cell Lymphoma

Objective: We have recently identified using multilayer perceptron analysis (artificial intelligence) a set of 25 genes with prognostic relevance in diffuse large B-cell lymphoma (DLBCL), but the importance of this set in other hematological neoplasia remains unknown. Methods and Results: We tested this set of genes (i.e., ALDOB, ARHGAP19, ARMH3, ATF6B, CACNA1B, DIP2A, EMC9, ENO3, GGA3, KIF23, LPXN, MESD, METTL21A, POLR3H, RAB7A, RPS23, SERPINB8, SFTPC, SNN, SPACA9, SWSAP1, SZRD1, TNFAIP8, WDCP and ZSCAN12) in a large series of gene expression comprised of 2029 cases, selected from available databases, that included chronic lymphocytic leukemia (CLL, n = 308), mantle cell lymphoma (MCL, n = 92), follicular lymphoma (FL, n = 180), DLBCL (n = 741), multiple myeloma (MM, n = 559) and acute myeloid leukemia (AML, n = 149). Using a risk-score formula we could predict the overall survival of the patients: the hazard-ratio of high-risk versus low-risk groups for all the cases was 3.2 and per disease subtype were as follows: CLL (4.3), MCL (5.2), FL (3.0), DLBCL not otherwise specified (NOS) (4.5), multiple myeloma (MM) (5.3) and AML (3.7) (all p values < 0.000001). All 25 genes contributed to the risk-score, but their weight and direction of the correlation was variable. Among them, the most relevant were ENO3, TNFAIP8, ATF6B, METTL21A, KIF23 and ARHGAP19. Next, we validated TNFAIP8 (a negative mediator of apoptosis) in an independent series of 97 cases of DLBCL NOS from Tokai University Hospital. The protein expression by immunohistochemistry of TNFAIP8 was quantified using an artificial intelligence-based segmentation method and confirmed with a conventional RGB-based digital quantification. We confirmed that high protein expression of TNFAIP8 by the neoplastic B-lymphocytes associated with a poor overall survival of the patients (hazard-risk 3.5; p = 0.018) as well as with other relevant clinicopathological variables including age >60 years, high serum levels of soluble IL2RA, a non-GCB phenotype (cell-of-origin Hans classifier), moderately higher MYC and Ki67 (proliferation index), and high infiltration of the immune microenvironment by CD163-positive tumor associated macrophages (CD163+TAMs). Conclusion: It is possible to predict the prognosis of several hematological neoplasia using a single gene-set derived from neural network analysis. High expression of TNFAIP8 is associated with poor prognosis of the patients in DLBCL.

Molecular mechanism of c-Myc and PRPS1/2 against thiopurine resistance in Burkitt's lymphoma

Patients with relapsed/refractory Burkitt's lymphoma (BL) have a dismal prognosis. Current research efforts aim to increase cure rates by identifying high-risk patients in need of more intensive or novel therapy. The 8q24 chromosomal translocation of the c-Myc gene, a main molecular marker of BL, is related to the metabolism by regulating phosphoribosyl pyrophosphate synthetase 2 (PRPS2). In our study, BL showed significant resistance to thiopurines. PRPS2 homologous isoenzyme, PRPS1, was demonstrated to play the main role in thiopurine resistance. c-Myc did not have direct effects on thiopurine resistance in BL for only driving PRPS2. PRPS1 wild type (WT) showed different resistance to 6-mercaptopurine (6-mp) in different metabolic cells because it could be inhibited by adenosine diphosphate or guanosine diphosphate negative feedback. PRPS1 A190T mutant could dramatically increase thiopurine resistance in BL. The interim analysis of the Treatment Regimen for Children or Adolescent with mature B cell non-Hodgkin's lymphoma in China (CCCG-B-NHL-2015 study) confirms the value of high-dose methotrexate (MTX) and cytarabine (ARA-C) in high-risk paediatric patients with BL. However, there remains a subgroup of patients with lactate dehydrogenase higher than four times of the normal value (4N) for whom novel treatments are needed. Notably, we found that the combination of thiopurines and the phosphoribosylglycinamide formyltransferase (GART) inhibitor lometrexol could serve as a therapeutic strategy to overcome thiopurine resistance in BL.

Raman-Enhanced Spectroscopy (RESpect) Probe for Childhood Non-Hodgkin Lymphoma

Raman-enhanced spectroscopy (RESpect) probe, which enhances Raman spectroscopy technology through a portable fiber-optic device, characterizes tissues and cells by identifying molecular chemical composition showing distinct differences/similarities for potential tumor markers or diagnosis. In a feasibility study with the ultimate objective to translate the technology to the clinic, a panel of pediatric non-Hodgkin lymphoma tissues and non-malignant specimens had RS analyses compared between standard Raman spectroscopy microscope instrument and RESpect probe. Cryopreserved tissues were mounted on front-coated aluminum mirror slides and analyzed by standard Raman spectroscopy and RESpect probe. Principal Component Analysis revealed similarities between non-Hodgkin lymphoma subtypes but not follicular hyperplasia. Standard Raman spectroscopy and RESpect probe fingerprint comparisons demonstrated comparable primary peaks. Raman spectroscopic fingerprints and peaks of pediatric non-Hodgkin lymphoma subtypes and follicular hyperplasia provided novel avenues to pursue diagnostic approaches and identify potential new therapeutic targets. The information could inform new insights into molecular cellular pathogenesis. Translating Raman spectroscopy technology by using the RESpect probe as a potential point-of-care screening instrument has the potential to change the paradigm of screening for cancer as an initial step to determine when a definitive tissue biopsy would be necessary.

Ibrutinib significantly inhibited Bruton's tyrosine kinase (BTK) phosphorylation,in-vitro proliferation and enhanced overall survival in a preclinical Burkitt lymphoma (BL) model

Pediatric and adult patients with recurrent/refractory Burkitt lymphoma (BL) continue to have poor outcomes, emphasizing the need for newer therapeutic agents. Bruton's tyrosine kinase (BTK) is activated following B-cell receptor stimulation and in part regulates normal B-cell development. Ibrutinib, a selective and irreversible BTK inhibitor, has been efficacious in chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), Waldenström's macroglobulinemia, and marginal zone lymphoma. In this study, we investigated the efficacy of ibrutinib alone and in selective adjuvant combinations against BL in-vitro and in a human BL xenografted immune-deficient NOD.Cg-Prkdc^scidIl2rg^tm1Wjl/SzJ (NSG) mouse model. Our data demonstrated that phospho-BTK level was significantly reduced in BL cells treated with ibrutinib (p < 0.001). Moreover, we observed a significant decrease in cell proliferation as well as significant decrease in IC₅₀ of ibrutinib in combination with dexamethasone, rituximab, obinutuzumab, carfilzomib, and doxorubicin (p < 0.001). In-vivo studies demonstrated ibrutinib treated mice had a significantly prolonged survival with median survival of mice following ibrutinib treatment (32 days) (24 days) (p < 0.02). In conclusion, our findings demonstrate the significant in-vitro and preclinical in-vivo effects of ibrutinib in BL. Based on our preclinical results in this investigation, there is an on-going clinical trial comparing overall survival in children and adolescents with relapsed/refractory BL treated with chemoimmunotherapy with or without ibrutinib (NCT02703272).

Overall survival of children and adolescents with mature B cell non-Hodgkin lymphoma who had refractory or relapsed disease during or after treatment with FAB/LMB 96: A report from the FAB/LMB 96 study group

We determined the risk factors associated with poor survival in children and adolescents with de novo mature B cell non-Hodgkin lymphoma (B-NHL) who had refractory or relapsed disease during or after the French-American-British mature lymphoma B (FAB/LMB) 96 multi-agent chemotherapy. Among the 1 111 registered on study, 104 patients (9·4%) had refractory disease or disease relapse after first complete remission. Among these 104 patients, 28 (27%) patients had refractory disease and 76 (73%) had relapsed disease. The estimated 1- and 2-year overall survival (OS) (95% confidence interval) was 31·5% (23·3-41·0%) and 22·3% (15·3-31·4%), respectively. Prognostic analysis of OS using a Cox multivariate model showed that factors independently associated with OS included lactate dehydrogenase ≥2 upper normal limit [hazard ratio (HR) = 2·86 (1·57-5·2), P = 0·0006]; time to failure (>6 months) [HR = 0·59 (0·36-0·97), P = 0·038]; and failure in bone marrow [HR = 2·78 (1·65-4·68), P = 0·0001]. New therapeutic strategies are required to significantly reduce refractory disease and disease relapse in patients with newly diagnosed mature B-NHL and, more importantly, there is a critical need to develop novel retrieval approaches in patients with chemotherapy-resistant disease.

Pre-clinical activity of targeting the PI3K/Akt/mTOR pathway in Burkitt lymphoma

Though outcomes for pediatric Burkitt lymphoma (BL) have improved significantly in recent decades with intensive multi-agent chemotherapy and the addition of rituximab, chemotherapy resistance remains a significant impediment to cure following relapse. Activation of the PI3K/AKT pathway has been implicated in Burkitt lymphomagenesis and increased PI3K/AKT activation has been associated with worse outcomes in adults with aggressive B-cell non-Hodgkin lymphoma (B-NHL). Inhibitors of the PI3K/AKT pathway have been approved for the treatment of refractory indolent B-NHL and continue to be investigated for treatment of aggressive B-NHLs. We investigated the activation of the PI3K/AKT pathway in a cell line model of resistant BL and the ability to target this pathway with small molecule inhibitors in BL cell lines. We found that cell lines resistant to rituximab and chemotherapy exhibited increased activation of PI3K/AKT and that inhibition of AKT or PI3K results in in vitro anti-lymphoma activity. To investigate the role of PI3K/AKT activation on the efficacy of cytotoxic chemotherapy, we exposed cells to inhibitors in combination with chemotherapy and noted a synergistic increase in response to chemotherapy. Overall these findings highlight the role of PI3K/AKT in chemotherapy resistance in BL cells and may represent a tractable therapeutic target.

Low expression of Mda-7/IL-24 and high expression of C-myb in tumour tissues are predictors of poor prognosis for Burkitt lymphoma patients

Objectives Burkitt lymphoma is one of the most common types of haematopoietic malignancy in children and adolescents. Mda-7/IL-24 had been identified as a differentiation inducer of Burkitt lymphoma cells. Previous studies have revealed that knockdown of C-myb can also lead to the terminal differentiation of Burkitt lymphoma cells. The aim of the present study was to investigate the correlation between the expression of Mda-7/IL-24 and C-myb, as well as their prognostic significance, for Burkitt lymphoma patients. Methods The tumour tissues were collected from 59 cases of Burkitt lymphoma patients and detected with Western blotting and immunohistochemistry. Results The results showed that the expression of Mda-7/IL-24 was lower, whereas the expression of C-myb was higher in Burkitt lymphoma tissues compared to specimens of normal lymph node tissues. Furthermore, C-myb expression was negatively correlated with Mda-7/IL-24 expression at the protein level in Burkitt lymphoma tissues and cell lines. Both the expression of Mda-7/IL-24 and C-myb in Burkitt lymphoma tissues was associated with some clinicopathological parameters, such as clinical stage, infiltration in the bone marrow, Ki67 and overall survival rates. Conclusion These results indicated that low expression of Mda-7/IL-24 along with high expression of C-myb are predictors for poor prognosis of Burkitt lymphoma patients; this outcome suggests that Mda-7/IL-24 and C-myb might be potential targets for clinical treatment of Burkitt lymphoma.

ABBREVIATIONS

Mda-7/IL-24: melanoma differentiation associated gene7/interleukin 24; FCM: flow cytometry; Ecog: Eastern Cooperative Oncology Group; IPI: International lymphoma prognosis index.

Hodgkin's lymphoma and its association with EBV and HIV infection

Hodgkin's lymphoma (HL) constitutes a clonal expansion of what appears to be malignant B cells. Viruses are involved in its pathogenesis, such as the Epstein-Barr virus (EBV) and human immunodeficiency virus (HIV). Since these viral infections have been shown to play key roles in the pathogenesis of HL, countries with a prevalence of HIV and EBV represent interesting population targets to study the pathogenesis of HL, linking the evolution of the disease with viral infections. Usually, patients present with late stage disease often involving the bone marrow at the time of diagnosis. The present paper discusses the role of viral infection in African countries, as HL is considered to be a malignant disease characterized by an inflammatory reaction to an aberrant B cell clone that is well known as the Reed-Sternberg cell (HRS).