Local and Systemic Immunity During Five Vaccinations Against SARS-CoV-2 in Zanubrutinib-Treated Patients With Chronic Lymphocytic Leukemia.

Background: Patients with chronic lymphocytic leukemia (CLL) are vulnerable to coronavirus disease 2019 (COVID-19) and are at risk of inferior response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination, especially if treated with the first-generation Bruton's tyrosine kinase inhibitor (BTKi) ibrutinib. We aimed to evaluate the impact of the third-generation BTKi, zanubrutinib, on systemic and mucosal response to SARS-CoV-2 vaccination. Methods: Nine patients with CLL with ongoing zanubrutinib therapy were included and donated blood and saliva during SARS-CoV-2 vaccination, before vaccine doses 3 and 5 and 2 - 3 weeks after doses 3, 4, and 5. Ibrutinib-treated control patients (n = 7) and healthy aged-matched controls (n = 7) gave blood 2 - 3 weeks after vaccine dose 5. We quantified reactivity and neutralization capacity of SARS-CoV-2-specific IgG and IgA antibodies (Abs) in both serum and saliva, and reactivity of T cells activated with viral peptides. Results: Both zanubrutinib- and ibrutinib-treated patients had significantly, up to 1,000-fold, lower total spike-specific Ab levels after dose 5 compared to healthy controls (P < 0.01). Spike-IgG levels in serum from zanubrutinib-treated patients correlated well to neutralization capacity (r = 0.68; P < 0.0001) and were thus functional. Mucosal immunity (specific IgA in serum and saliva) was practically absent in zanubrutinib-treated patients even after five vaccine doses, whereas healthy controls had significantly higher levels (tested in serum after vaccine dose 5) (P < 0.05). In contrast, T-cell reactivity against SARS-CoV-2 peptides was equally high in zanubrutinib- and ibrutinib-treated patients as in healthy control donors. Conclusions: In our small cohort of zanubrutinib-treated CLL patients, we conclude that up to five doses of SARS-CoV-2 vaccination induced no detectable IgA mucosal immunity, which likely will impair the primary barrier defence against the infection. Systemic IgG responses were also impaired, whereas T-cell responses were normal. Further and larger studies are needed to evaluate the impact of these findings on disease protection.

A Small Molecule Targeting the Intracellular Tyrosine Kinase Domain of ROR1 (KAN0441571C) Induced Significant Apoptosis of Non-Small Cell Lung Cancer (NSCLC) Cells.

The ROR1 receptor tyrosine kinase is expressed in embryonic tissues but is absent in normal adult tissues. ROR1 is of importance in oncogenesis and is overexpressed in several cancers, such as NSCLC. In this study, we evaluated ROR1 expression in NSCLC patients (N = 287) and the cytotoxic effects of a small molecule ROR1 inhibitor (KAN0441571C) in NSCLC cell lines. ROR1 expression in tumor cells was more frequent in non-squamous (87%) than in squamous (57%) carcinomas patients, while 21% of neuroendocrine tumors expressed ROR1 (p = 0.0001). A significantly higher proportion of p53 negative patients in the ROR1+ group than in the p53 positive non-squamous NSCLC patients (p = 0.03) was noted. KAN0441571C dephosphorylated ROR1 and induced apoptosis (Annexin V/PI) in a time- and dose-dependent manner in five ROR1+ NSCLC cell lines and was superior compared to erlotinib (EGFR inhibitor). Apoptosis was confirmed by the downregulation of MCL-1 and BCL-2, as well as PARP and caspase 3 cleavage. The non-canonical Wnt pathway was involved. The combination of KAN0441571C and erlotinib showed a synergistic apoptotic effect. KAN0441571C also inhibited proliferative (cell cycle analyses, colony formation assay) and migratory (scratch wound healing assay) functions. Targeting NSCLC cells by a combination of ROR1 and EGFR inhibitors may represent a novel promising approach for the treatment of NSCLC patients.

A ROR1 Small Molecule Inhibitor (KAN0441571C) Induced Significant Apoptosis of Mantle Cell Lymphoma (MCL) Cells.

The receptor tyrosine kinase orphan receptor 1 (ROR1) is absent in most normal adult tissues but overexpressed in various malignancies and is of importance for tumor cell survival, proliferation, and metastasis. In this study, we evaluated the apoptotic effects of a novel small molecule inhibitor of ROR1 (KAN0441571C) as well as venetoclax (BCL-2 inhibitor), bendamustine, idelalisib (PI3Kδ inhibitor), everolimus (mTOR inhibitor), and ibrutinib (BTK inhibitor) alone or in combination in human MCL primary cells and cell lines. ROR1 expression was evaluated by flow cytometry and Western blot (WB). Cytotoxicity was analyzed by MTT and apoptosis by Annexin V/PI staining as well as signaling and apoptotic proteins (WB). ROR1 was expressed both in patient-derived MCL cells and human MCL cell lines. KAN0441571C alone induced significant time- and dose-dependent apoptosis of MCL cells. Apoptosis was accompanied by decreased expression of MCL-1 and BCL-2 and cleavage of PARP and caspase 3. ROR1 was dephosphorylated as well as ROR1-associated signaling pathway molecules, including the non-canonical WNT signaling pathway (PI3Kδ/AKT/mTOR). The combination of KAN0441571C and ibrutinib, venetoclax, idelalisib, everolimus, or bendamustine had a synergistic apoptotic effect and significantly prevented phosphorylation of ROR1-associated signaling molecules as compared to KAN0441571C alone. Our results suggest that targeting ROR1 by a small molecule inhibitor, KAN0441571C, should be further evaluated particularly in combination with other targeting drugs as a new therapeutic approach for MCL.

Targeting the Receptor Tyrosine Kinase ROR1 by Small Molecules.

Receptor tyrosine kinases (RTKs) are frequently dysregulated in malignancies and important for the malignant characteristics of tumor cells. RTKs are attractive structures for drug targeting of cancer. The RTK ROR1 is of significance during embryogenesis but downregulated in post-partum tissues. However, ROR1 is overexpressed in several hematological and solid tumors and important for tumor cell proliferation, survival, migration, and metastasis. WNT5a is a main ligand for ROR1. Several clinical trials are ongoing using anti-ROR1 antibody based drugs directed against the external domain (monoclonal antibodies, BiTE, CAR-T). We have produced small molecules (KAN834/1571c) fitting to the ATP pocket of the intracellular tyrosine kinase (TK) domain of ROR1 (TK inhibitor, TKI). These inhibitors of ROR1 prevented ROR1 phosphorylation and inactivated the WNT/ß-catenin independent as well as WNT/ß-catenin dependent pathways. ROR1-TKI induced apoptosis of ROR1 positive fresh patient derived tumor cells and appropriate cell lines and a dose and time dependent tumor reduction in animal models. In combination with other clinically relevant targeting drugs as venetoclax a synergistic apoptotic effect was seen. Two other small molecules (ARI-1 and strictinin) bound also to ROR1 and inhibited tumor growth. Development of small molecule ROR1 inhibitors is warranted to include this novel therapeutic approach for cancer therapy.

Predicting ROR1/BCL2 combination targeted therapy of small cell carcinoma of the lung.

Small cell lung cancer (SCLC) remains a deadly form of cancer, with a 5-year survival rate of less than 10 percent, necessitating novel therapies. Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is an oncofetal protein that is emerging as a therapeutic target and is co-expressed with BCL2 in multiple tumor types due to microRNA coregulation. We hypothesize that ROR1-targeted therapy is effective in small cell lung cancer and synergizes with therapeutic BCL2 inhibition. Tissue microarrays (TMAs) and formalin-fixed paraffin-embedded (FFPE) SCLC patient samples were utilized to determine the prevalence of ROR1 and BCL2 expression in SCLC. Eight SCLC-derived cell lines were used to determine the antitumor activity of a small molecule ROR1 inhibitor (KAN0441571C) alone and in combination with the BCL2 inhibitor venetoclax. The Chou-Talalay method was utilized to determine synergy with the drug combination. ROR1 and BCL2 protein expression was identified in 93% (52/56) and 86% (48/56) of SCLC patient samples, respectively. Similarly, ROR1 and BCL2 were shown by qRT-PCR to have elevated expression in 79% (22/28) and 100% (28/28) of SCLC patient samples, respectively. KAN0441571C displayed efficacy in 8 SCLC cell lines, with an IC50 of 500 nM or less. Synergy as defined by a combination index of <1 via the Chou-Talalay method between KAN0441571C and venetoclax was demonstrated in 8 SCLC cell lines. We have shown that ROR1 inhibition is synergistic with BCL2 inhibition in SCLC models and shows promise as a novel therapeutic target in SCLC.

A ROR1 small molecule inhibitor (KAN0441571C) induced significant apoptosis of ibrutinib-resistant ROR1+ CLL cells.

ROR1 - a receptor tyrosine kinase - is overexpressed in CLL. Ibrutinib, a Bruton's tyrosine kinase inhibitor, is clinically effective in CLL but patients may develop resistance. We evaluated the effect of an ROR1 inhibitor, KAN0441571C, in CLL cells from six patients obtained before and after developing resistance to ibrutinib. The ROR1 inhibitor induced apoptosis in ibrutinib-resistant CLL cells to the same degree as in ibrutinib-sensitive cells and dephosphorylated ROR1. This was also noted in one patient who became resistant to both ibrutinib and the Bcl-2 inhibitor venetoclax. The combination of ROR1 inhibitor and venetoclax had a synergistic apoptotic effect on ibrutinib-resistant cells.

Temporary cessation of ibrutinib results in reduced grade 3-4 infections and durable remissions-Interim analysis of an on-off-repeat Phase 1b/2 study in patients with chronic lymphocytic leukemia.

Ibrutinib is used continuously in CLL. This phase 1b/2 study interim analysis explored on-off-repeat dosing to reduce toxicity. After 12 months, 16/22 patients (73%) remained in first off-phase irrespective if initial CR/PR or TP53 aberration. Grade 3-4 infections were reduced from 55% to 5% during a similarly long off-phase (P < .01). Treg and exhausted T-cells increased (P = .01). Six patients restarted ibrutinib at early progression and remain drug-sensitive. Our interim analysis shows a durable off-phase in most patients, with reduced infections and cost-saving potential. If toxicity-driven permanent cessation of ibrutinib will be affected will be explored in the extended study.

Polymorphisms within methotrexate pathway genes: Relationship between plasma methotrexate levels, toxicity experienced and outcome in pediatric acute lymphoblastic leukemia.

OBJECTIVES: The current study aimed to investigate the relationship of genetic polymorphism and plasma methotrexate (MTX) levels, toxicity experience and event free survival (EFS) in pediatric acute lymphoblastic leukemia (ALL). MATERIALS AND METHODS: The study included 74 ALL patients. Polymerase chain reaction and genotyping of methylene tetrahydrofolate reductase (MTHFR) rs1801133, MTHFR rs1801131, ATP-binding cassette superfamily B1 (ABCB1) rs1045642, ATP-binding cassette superfamily G2 (ABCG2) rs2231142 and solute carrier 19A1 (SLC19A1) rs1051266 genetic variations were performed. The plasma MTX levels were investigated at 48 hr after the first dose of MTX infusion. RESULTS: MTHFR rs1801133 TT genotype, ABCBa1 rs1045642 CT genotype and ABCG2 rs2231142 CA genotype revealed a statistically significant association with the MTX plasma levels (P<0.01, P<0.05, P<0.05, respectively). The MTHFR rs1801133 TT genotype had a statistically significant association with hematopoietic toxicity (P<0.01) and interventions (P<0.05). The MTHFR rs1801131 AC genotype was related to the decreased hepatic toxicity (P<0.05). The SLC19A1 rs 1051266 GA genotype was related to the increased hepatic toxicity (P<0.05). Only the ABCB1 rs1045642 CT and TT genotypes had a statistically significant correlation with EFS (P<0.05, P<0.05, respectively). CONCLUSION: Our findings showed that genetic polymorphism could be associated with plasma MTX levels, toxicity experienced and EFS in Iranian pediatric ALL.

ROR1 Is Expressed in Diffuse Large B-Cell Lymphoma (DLBCL) and a Small Molecule Inhibitor of ROR1 (KAN0441571C) Induced Apoptosis of Lymphoma Cells.

The receptor tyrosine kinase ROR1 is absent in most normal adult tissues, but overexpressed in several malignancies. In this study, we explored clinical and functional inhibitory aspects of ROR1 in diffuse large B-cell lymphoma (DLBCL). ROR1 expression in tumor cells was more often observed in primary refractory DLBCL, Richter's syndrome and transformed follicular lymphoma than in relapsed and non-relapsed DLBCL patients (p < 0.001). A survival effect of ROR1 expression was preliminarily observed in relapsed/refractory patients independent of gender and stage but not of age, cell of origin and international prognostic index. A second generation small molecule ROR1 inhibitor (KAN0441571C) induced apoptosis of ROR1+ DLBCL cell lines, similar to venetoclax (BCL-2 inhibitor) but superior to ibrutinib (BTK inhibitor). The combination of KAN0441571C and venetoclax at EC50 concentrations induced almost complete killing of DLBCL cell lines. Apoptosis was accompanied by the downregulation of BCL-2 and MCL-1 and confirmed by the cleavage of PARP and caspases 3, 8, 9. PI3Kδ/AKT/mTOR (non-canonical Wnt pathway) as well as ß-catenin and CK1δ (canonical pathway) were inactivated. In zebra fishes transplanted with a ROR1+ DLBCL cell line, KAN0441571C induced a significant tumor reduction. New drugs with mechanisms of action other than those available for DLBCL are warranted. ROR1 inhibitors might represent a novel promising approach.

A receptor tyrosine kinase ROR1 inhibitor (KAN0439834) induced significant apoptosis of pancreatic cells which was enhanced by erlotinib and ibrutinib.

There is a great unmet medical need in pancreatic carcinoma (PC) for novel drugs with other mechanisms of action than existing. PC cells express the onco-fetal RTK ROR1, absent on most normal post-partem cells. ROR1 is involved in proliferation, survival, EMT and metastasis of tumor cells in various malignancies. A small molecule inhibitor (KAN0439834) (530 Da) targeting the TK domain of ROR1 was developed and the activity in ROR1 expressing human PC cell lines (n = 8) evaluated. The effects were compared to a murine mAb against the external part of ROR1, gemcitabine, erlotinib and ibrutinib. KAN0439834 induced significant apoptosis of the tumor cells. EC50 values for KAN0439834 varied between 250-650 nM depending on the cell line. The corresponding values for erlotinib and ibrutinib were 10-40 folds higher. KAN0439834 was much more effective in inducing tumor cell death than the ROR1 mAb although both inhibited ROR1 phosphorylation and downstream non-canonical Wnt pathway molecules. Combination of KAN0439834 with erlotinib or ibrutinib had significant additive effects on tumor cell death. A first-in-class small molecule ROR1 inhibitor (KAN0439834) showed promising in vitro activity against a number of human PC cell lines. Interesting is the additive effects of erlotinib and ibrutinib which warrants further studies as both these agents are in clinical trials for pancreatic carcinoma.

Lenalidomide as immune adjuvant to a dendritic cell vaccine in chronic lymphocytic leukemia patients.

OBJECTIVES: We previously showed that immunization with ex vivo- generated autologous dendritic cells loaded with apoptotic tumor cells (Apo-DC) potentiated tumor-specific immunity in chronic lymphocytic leukemia (CLL) patients. Here, we evaluated safety and immunogenicity of Apo-DC in combination with lenalidomide, granulocyte-macrophage colony-stimulating factor (GM-CSF), and low-dose cyclophosphamide (CTX). METHODS: Ten previously untreated patients with slowly progressing CLL received 5 Apo-DC vaccinations and lenalidomide orally for 24 weeks either alone (cohort I, n = 5) or together with subcutaneous GM-CSF and intravenous CTX (cohort II, n = 5). Tumor-specific T-cell responses were measured by proliferation and IFN-γ ELISPOT assays. Immune monitoring was performed by flow cytometry. RESULTS: Dose-limiting toxicity was observed in 3/10 patients, 2 in cohort I and one in cohort II. One patient developed autoimmune hemolytic anemia and another grade 4 thrombocytopenia. Vaccine-induced immune responses were seen in 5/5 and 4/5 patients in cohort I and II, respectively. The expression of immune checkpoints on T cells did not change significantly. CONCLUSIONS: Lenalidomide alone or in combination with GM-CSF and low-dose CTX as immune adjuvant to the Apo-DC vaccine elicited tumor-specific T-cell responses in CLL patients. However, unexpected toxicity was observed and caution is suggested in further exploring this drug as immune adjuvant in CLL.

Autologous T cells expressing the oncogenic transcription factor KLF6-SV1 prevent apoptosis of chronic lymphocytic leukemia cells.

Crosstalk between leukemic cells and the tumor microenvironment is of importance in chronic lymphocytic leukemia (CLL). T cells seem to sustain the survival of CLL cells by various mechanisms. The Krüppel-like family of transcription factors (KLFs) are identified as regulators of proliferation and cell death. In the present study, we analyzed the expression of the wild type (WT) gene KLF6 and the oncogenic splice variant 1 (KLF6-SV1) at the mRNA level in subsets of T cells from CLL patients (n = 29), multiple myeloma patients (n = 6) and normal donors (n = 10). RNA Silencing was used for wtKLF6 and KLF6-SV1. Tumor cell apoptosis was measured. A significant overexpression of wtKLF6 and KLF6-SV1 in T cells of CLL patients compared to normal donors and myeloma patients was noted (p<0.002). Western blot showed that both wtKLF6 and KLF6-SV1 were expressed in purified T cells from CLL patients. KLF6-SV1 siRNA transfection induced a significant down-regulation of KLF6-SV1 in CLL T cells, which lost the capability to sustain the growth of leukemic cells. However, no such a significant effect was seen after wtKLF6 transfection of the autologous T cells. The results suggest that KLF6-SV1 may play a role in the regulation of survival CLL cells.

Glioblastoma-synthesized G-CSF and GM-CSF contribute to growth and immunosuppression: Potential therapeutic benefit from dapsone, fenofibrate, and ribavirin.

Increased ratio of circulating neutrophils to lymphocytes is a common finding in glioblastoma and other cancers. Data reviewed establish that any damage to brain tissue tends to cause an increase in G-CSF and/or GM-CSF (G(M)-CSF) synthesized by the brain. Glioblastoma cells themselves also synthesize G(M)-CSF. G(M)-CSF synthesized by brain due to damage by a growing tumor and by the tumor itself stimulates bone marrow to shift hematopoiesis toward granulocytic lineages away from lymphocytic lineages. This shift is immunosuppressive and generates the relative lymphopenia characteristic of glioblastoma. Any trauma to brain-be it blunt, sharp, ischemic, infectious, cytotoxic, tumor encroachment, or radiation-increases brain synthesis of G(M)-CSF. G(M)-CSF are growth and motility enhancing factors for glioblastomas. High levels of G(M)-CSF contribute to the characteristic neutrophilia and lymphopenia of glioblastoma. Hematopoietic bone marrow becomes entrained with, directed by, and contributes to glioblastoma pathology. The antibiotic dapsone, the lipid-lowering agent fenofibrate, and the antiviral drug ribavirin are Food and Drug Administration- and European Medicines Agency-approved medicines that have potential to lower synthesis or effects of G(M)-CSF and thus deprive a glioblastoma of some of the growth promoting contributions of bone marrow and G(M)-CSF.

Clinical and Immune Effects of Lenalidomide in Combination with Gemcitabine in Patients with Advanced Pancreatic Cancer.

PURPOSE: To assess the immunomodulatory and clinical effects of lenalidomide with standard treatment of gemcitabine in patients with advanced pancreatic cancer. PATIENTS AND METHODS: Patients with advanced pancreatic cancer were treated in first line with lenalidomide orally for 21 days of a 28 days cycle and the standard regimen for gemcitabine. In Part I, which we previously have reported, the dose of lenalidomide was defined (n = 12). In Part II, every other consecutive patient was treated with either lenalidomide (Group A, n = 11) or gemcitabine (Group B, n = 10) during cycle 1. From cycle 2 on, all Part II patients received the combination. RESULTS: A significant decrease in the proliferative response of peripheral blood mononuclear cells and the frequency of DCs were noted in patients at baseline compared to healthy control donors while the frequencies of CD4+ and CD8+ T cells, NK-cells and MDSCs were significantly higher in patients compared to controls. In Group A, a significant increase in the absolute numbers of activated (HLA-DR+) CD4 and CD8 T cells and CD8 effector memory T cells (p<0.01) was noted during treatment. A statistical increment in the absolute numbers of Tregs were seen after cycle 1 (p<0.05). The addition of gemcitabine, reduced most lymphocyte subsets (p<0.05). In Group B, the proportion of lymphocytes remained unchanged during the study period. There was no difference in overall survival, progression free survival and survival rate at one year comparing the two groups. DISCUSSION: Patients with advanced pancreatic carcinoma had impaired immune functions. Lenalidomide augmented T cell reactivities, which were abrogated by gemcitabine. However, addition of lenalidomide to gemcitabine seemed to have no therapeutic impact compared to gemcitabine alone in this non-randomized study. TRIAL REGISTRATION: ClinicalTrials.gov NCT01547260.

T cells in chronic lymphocytic leukemia display dysregulated expression of immune checkpoints and activation markers.

Chronic lymphocytic leukemia is characterized by impaired immune functions largely due to profound T-cell defects. T-cell functions also depend on co-signaling receptors, inhibitory or stimulatory, known as immune checkpoints, including cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and programmed death-1 (PD-1). Here we analyzed the T-cell phenotype focusing on immune checkpoints and activation markers in chronic lymphocytic leukemia patients (n=80) with different clinical characteristics and compared them to healthy controls. In general, patients had higher absolute numbers of CD3+ cells and the CD8+ subset was particularly expanded in previously treated patients. Progressive patients had higher numbers of CD4+ and CD8+ cells expressing PD-1 compared to healthy controls, which was more pronounced in previously treated patients (P=0.0003 and P=0.001, respectively). A significant increase in antigen-experienced T cells was observed in patients within both the CD4+ and CD8+ subsets, with a significantly higher PD-1 expression. Higher numbers of CD4+ and CD8+ cells with intracellular CTLA-4 were observed in patients, as well as high numbers of proliferating (Ki67+) and activated (CD69+) CD4+ and CD8+ cells, more pronounced in patients with active disease. The numbers of Th1, Th2, Th17 and regulatory T cells were substantially increased in patients compared to controls (P<0.05), albeit decreasing to low levels in pre-treated patients. In conclusion, chronic lymphocytic leukemia T cells display increased expression of immune checkpoints, abnormal subset distribution, and a higher proportion of proliferating cells compared to healthy T cells. Disease activity and previous treatment shape the T-cell profile of chronic lymphocytic leukemia patients in different ways.

Phase I-II study of lenalidomide and alemtuzumab in refractory chronic lymphocytic leukemia (CLL): effects on T cells and immune checkpoints.

This phase I-II study explored safety, immunomodulatory and clinical effects of lenalidomide (weeks 1-16) and alemtuzumab (weeks 5-16) in 23 patients with refractory chronic lymphocytic leukemia. Most patients had Rai stage III/IV disease and were heavily pretreated (median 4 prior therapies), and 61% had del(17p)/del(11q). Eleven of 19 evaluable patients (58%) responded, with a median response duration of 12 months (1-29+); time to progression was short in non-responders. Lenalidomide had a narrow therapeutic dose range, 2.5 mg/day was not efficient, and maximum tolerated dose was 5 mg/day. Grade 3-4 neutropenia and thrombocytopenia occurred in 84 and 55%, 30% had febrile neutropenia, and CMV-reactivation requiring valganciclovir occurred in 30% of patients. The frequency of proliferating (Ki67+) CD8+ T cells was increased at week 4, with further increase in both the CD4+ and CD8+ subsets (p < 0.01 and <0.05), which was accompanied by significant upregulation of HLA-DR after addition of alemtuzumab. Antigen-experienced cells increased at week 4 as the frequency of effector memory cells increased in the CD8+ subset (p < 0.003), while effector cells decreased in both the CD8+ and CD4+ subsets (p < 0.0001 and p < 0.01). The Th1/Th2 balance was unchanged at week 4 but shifted toward a Th2 profile after combination therapy. At end of treatment, the frequency of Th17 and regulatory T cells was reduced (p < 0.01), naïve T cells decreased, and effector memory T cells increased (p < 0.05 and p < 0.01). Granzyme B+ T cells increased at 30-week follow-up (p < 0.05). PD-1 expression was unaffected. In conclusion, low-dose lenalidomide and alemtuzumab induced major perturbations of T cells, including increased proliferative activity and cytotoxic potential.

Differential expression of viral agents in lymphoma tissues of patients with ABC diffuse large B-cell lymphoma from high and low endemic infectious disease regions.

Diffuse large B-cell lymphoma (DLBCL), the most common type of non-Hodgkin's lymphoma (NHL) in adults, accounts for approximately 30-40% of newly diagnosed lymphomas worldwide. Environmental factors, such as viruses and bacteria, may contribute to cancer development through chronic inflammation and the integration of oncogenes, and have previously been indicated in cervical cancer, hepatocellular carcinoma, gastric cancer and lymphoproliferative disorders. In the present study, the presence of microbial agents was analyzed in the lymphoma tissue of patients with activated B-cell like (ABC) DLBCL. The present study compared two groups of patients from geographically varied regions that possess a difference in the prevalence of viral and other microbial agents. The patient populations were from Sweden (a low endemic infectious disease region) and Egypt (a high endemic infectious disease region). A differential expression of several viruses in lymphoma tissues was noted when comparing Swedish and Egyptian patients. JC polyomavirus (JCV) was detected in Swedish and Egyptian patients and, uniquely, the complete hepatitis B virus (HBV) genome was detected only in Egyptian lymphoma patients. None of these viruses were detected in control lymph tissues from Sweden or Egypt. In total, 38% of the Egyptian patients were found to have HBV surface antigens (HBsAgs) in their serum; however, HBsAgs were not found in any of the Swedish patients. The percentage of serum HBsAgs in Egyptian patients with ABC DLBCL was significantly increased compared with the general Egyptian population (P<0.05). The present study may support a notion that viral agents, including JCV and HBV, may be involved in the tumorigenesis of DLBCL in regions of high infectious disease.