Preclinical activity of anti-CCR7 immunotherapy in patients with high-risk chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) with deletions of the p53 locus on chromosome 17 and/or refractory to fludarabine chemoimmunotherapy remains a major clinical problem with few therapeutic options. Currently, these types of CLL are treated with approaches that do not target the p53 pathway, such as small molecules and monoclonal antibodies (mAb). We have previously postulated anti-CCR7 mAb therapy as a novel CLL treatment. In the present study, we evaluated the in vitro efficacy of anti-CCR7 mAb as a single agent in CLL patients with high-risk cytogenetics and/or refractory to fludarabine, by measuring CCR7 surface expression and complement-dependent cytotoxicity. Our results demonstrate that CCR7 is highly expressed in challenging and heavily treated CLL patients. In addition, the complement-mediated mechanism of action of this mAb effectively eradicates CLL cells while sparing subsets of T cells in these patients. Moreover, this mAb outperformed the activity of alemtuzumab, the mAb with the highest efficacy in these groups. Finally, in vitro activity was also demonstrated in patients with a disease refractory to both fludarabine and alemtuzumab, and patients harboring 11q22 deletion. Our results propose that anti-CCR7 mAb is an effective and promising future treatment in high-risk CLL.

Action and resistance of monoclonal CD20 antibodies therapy in B-cell Non-Hodgkin Lymphomas

Anti-CD20 monoclonal antibodies (mAbs) have improved patient's survival with Non-Hodgkin Lymphoma, when combined with chemotherapy. Several mechanisms of action have been reported, including antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity and induction of apoptosis. Despite the large amount of studies and published data, the role each mechanism played in vivo is not fully understood. Furthermore, the reason why a significant percentage of patients are refractory or resistant remains unknown. Several activated intracellular signaling pathways have been implicated in the mechanisms of resistance of rituximab. In the present manuscript, we review those mechanisms and new anti-CD20 mAbs, as well as the efforts being accomplished to overcome it, focusing on new drugs targeting pathways implicated in resistance to rituximab.

Inhibition of CD47 Effectively Targets Pancreatic Cancer Stem Cells via Dual Mechanisms

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is a cancer of the exocrine pancreas with unmet medical need and is strongly promoted by tumor-associated macrophages (TAM). The presence of TAMs is associated with poor clinical outcome, and their overall role, therefore, appears to be protumorigenic. The "don't eat me" signal CD47 on cancer cells communicates to the signal regulatory protein-α on macrophages and prevents their phagocytosis. Thus, inhibition of CD47 may offer a new opportunity to turn TAMs against PDAC cells, including cancer stem cells (CSC), as the exclusively tumorigenic population.

EXPERIMENTAL DESIGN

We studied in vitro and in vivo the effects of CD47 inhibition on CSCs using a large set of primary pancreatic cancer (stem) cells as well as xenografts of primary human PDAC tissue.

RESULTS

CD47 was highly expressed on CSCs, but not on other nonmalignant cells in the pancreas. Targeting CD47 efficiently enhanced phagocytosis of a representative set of primary human pancreatic cancer (stem) cells and, even more intriguingly, also directly induced their apoptosis in the absence of macrophages during long-term inhibition of CD47. In patient-derived xenograft models, CD47 targeting alone did not result in relevant slowing of tumor growth, but the addition of gemcitabine or Abraxane resulted in sustained tumor regression and prevention of disease relapse long after discontinuation of treatment.

CONCLUSIONS

These data are consistent with efficient in vivo targeting of CSCs, and strongly suggest that CD47 inhibition could be a novel adjuvant treatment strategy for PDAC independent of underlying and highly variable driver mutations.

Antagonistic human FcγRIIB (CD32B) antibodies have anti-tumor activity and overcome resistance to antibody therapy in vivo

Therapeutic antibodies have transformed cancer therapy, unlocking mechanisms of action by engaging the immune system. Unfortunately, cures rarely occur and patients display intrinsic or acquired resistance. Here, we demonstrate the therapeutic potential of targeting human (h) FcγRIIB (CD32B), a receptor implicated in immune cell desensitization and tumor cell resistance. FcγRIIB-blocking antibodies prevented internalization of the CD20-specific antibody rituximab, thereby maximizing cell surface accessibility and immune effector cell mediated antitumor activity. In hFcγRIIB-transgenic (Tg) mice, FcγRIIB-blocking antibodies effectively deleted target cells in combination with rituximab, and other therapeutic antibodies, from resistance-prone stromal compartments. Similar efficacy was seen in primary human tumor xenografts, including with cells from patients with relapsed/refractory disease. These data support the further development of hFcγRIIB antibodies for clinical assessment.

Nonpegylated Liposomal Doxorubicin as a Component of R-CHOP Is an Effective and Safe Alternative to Conventional Doxorubicin in the Treatment of Patients With Diffuse Large B-Cell Lymphoma and Preexisting Cardiac Diseases

INTRODUCTION

The aim of this retrospective analysis was to investigate the efficacy and safety of nonpegylated liposomal doxorubicin (NPLD) as part of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone) in patients with diffuse large B-cell lymphoma (DLBCL) and preexisting cardiac diseases.

PATIENTS AND METHODS

Twenty-five patients were evaluated, median age was 73 (range 24-85) years, 23 patients received NPLD as part of their first-line therapy. Most patients suffered from more than 1 cardiac disease and in 14 patients left ventricular ejection fraction (LVEF) was reduced. One hundred nineteen cycles of NPLD were applied with a median of 5 (range 2-8) cycles per patient. Median dose per cycle was 95 mg (50 mg/m(2)).

RESULTS

The overall response rate was 96% (44% complete remission, 52% partial remission). After a median follow-up of 23 months, 4 patients had disease relapse. Seven patients died, translating to an estimated 3-year progression-free and overall survival of 66% and 73%, respectively. Reasons for death were progressive disease or infection in 2 patients each and cardiovascular disease in 3 patients. After chemotherapy, LVEF decreased significantly in 28% and improved in 12% of patients, whereas median LVEF did not change (51% vs. 50%). No higher frequencies of decreased LVEF was observed in the group of patients with preexisting reduced LVEF. Five adverse events induced therapy termination: 2 myocardial infarctions, 2 pneumonias, and 1 reduced condition. No hand-foot-syndrome was observed.

CONCLUSION

NPLD as a component of R-CHOP is an effective treatment in patients with DLBCL and preexisting cardiac diseases, whereas cardiac events were observed in 36% of patients in this cardiac high-risk group. However, these results need to be confirmed in a prospective randomized trial.

Combination immunotherapy with 4-1BB activation and PD-1 blockade enhances antitumor efficacy in a mouse model of subcutaneous tumor

BACKGROUND/AIM

The purpose of the present study was to establish an effective immunotherapy by skewing the cosignal balance to be on the positive side by using the combination of monoclonal antibody (mAb) against 4-1BB also known as Cluster of Differentiation (CD) 137 as a co-stimulatory effector and to programmed death-1 (PD-1) to blockade the immune checkpoint.

MATERIALS AND METHODS

Mice implanted with 1×10(5) CT26 cells were treated with anti 4-1BB mAb alone, anti PD-1 mAb alone, or both anti 4-1BB mAb and anti PD-1 mAb. Immune cell populations were analyzed by flow cytometry. Tumor-infiltrating T-cells were evaluated by immunohistochemistry.

RESULTS

Mice treated with the combination therapy had the best antitumor response that resulted in complete tumor rejection. The numbers of CD4(+) interferon (IFN)-γ(+) and CD8(+) IFN-γ(+) T-cells were significantly higher in the combination group. The number of tumor-infiltrating T-cells was significantly increased in the combination therapy.

CONCLUSION

The therapeutic strategy of targeting co-signal molecules has promising clinical applications in the future.

Generation of potent mouse monoclonal antibodies to self-proteins using T-cell epitope "tags"

Immunization of mice or rats with a "non-self" protein is a commonly used method to obtain monoclonal antibodies, and relies on the immune system's ability to recognize the immunogen as foreign. Immunization of an antigen with 100% identity to the endogenous protein, however, will not elicit a robust immune response. To develop antibodies to mouse proteins, we focused on the potential for breaking such immune tolerance by genetically fusing two independent T-cell epitope-containing sequences (from tetanus toxin (TT) and diphtheria toxin fragment A (DTA)) to a mouse protein, mouse ST2 (mST2). Wild-type CD1 mice were immunized with three mST2 tagged proteins (Fc, TT and DTA) and the specific serum response was determined. Only in mice immunized with the T-cell epitope-containing antigens were specific mST2 serum responses detected; hybridomas generated from these mice secreted highly sequence-diverse IgGs that were capable of binding mST2 and inhibiting the interaction of mST2 with its ligand, mouse interleukin (IL)-33 (mIL-33). Of the hundreds of antibodies profiled, we identified five potent antibodies that were able to inhibit IL-33 induced IL-6 release in a mast cell assay; notably one such antibody was sufficiently potent to suppress IL-5 release and eosinophilia infiltration in an Alternaria alternata challenge mouse model of asthma. This study demonstrated, for the first time, that T-cell epitope-containing tags have the ability to break tolerance in wild-type mice to 100% conserved proteins, and it provides a compelling argument for the broader use of this approach to generate antibodies against any mouse protein or conserved ortholog.

[Development of a novel reporter gene method for determination of ADCC potency of anti-CD20 monoclonal antibody]

The biological activity of ADCC by anti-CD20 monoclonal antibody was determined by BioGlo™ Luciferase Assay System using Jurkat/NFAT-luc+FcγRIIIa cell line as effector cell and WIL2-S cell line as target cell. The developed method was verified for specificity, precision and accuracy. Anti-CD20 monoclonal antibody showed a dose-response mode by the developed method, and the determination result complied with the following four-parameter equation: y = (A-D)/[1 + (X/C)(B)] + D. The optimized parameters of the method were determined including the antibodies diluted concentration (18,000 ng·mL(-1)), dilution rate (1:5), the ratio of effector cell and target cell (6:1), and induction time (6 h). The values of eight independent tests have passed a statistical test for curve regression analysis, linear or parallelism, which showed the method possessed good specificity. Four different dilute groups of recovery rates sample were determined for 3 times, and the result showed mean relative potencies of (44.39±3.93)%, (72.74±2.78)%, (128.28±7.01)% and (168.19±2.70)% respectively, with a variation coefficient of less than 10%, and the recoveries of (88.78±7.85)%, (96.99±3.70)%, (102.63±5.61)% and (112.12±1.80)% respectively. A novel reporter gene method for determination of biological activity of ADCC by anti-CD20 monoclonal antibody was successfully developed, which showed strong specificity, good reproducibility and high accuracy, and might be used routinely.

Prolonged B cell depletion with rituximab is effective in treating refractory pulmonary granulomatous inflammation in granulomatosis with polyangiitis (GPA)

Pulmonary nodule formation is a frequent feature of granulomatosis with polyangiitis (GPA). Traditional induction therapy includes methotrexate or cyclophosphamide, however, pulmonary nodules generally respond slower than vasculitic components of disease. Efficacy of rituximab (RTX) solely for the treatment of pulmonary nodules has not been assessed. In this observational cohort study, we report patient outcomes with RTX in GPA patients with pulmonary nodules who failed to achieve remission following conventional immunosuppression. Patients (n = 5) with persistent pulmonary nodules were identified from our clinic database and retrospectively evaluated. Systemic manifestations, inflammatory markers, disease activity, concurrent immunosuppression, and absolute B cell numbers were recorded pre-RTX and at 6 monthly intervals following treatment. Chest radiographs at each time point were scored by an experienced radiologist, blinded to clinical details. Five patients with GPA and PR3-ANCA were evaluated (2 male, 3 female), mean age 34 (22-52) years. Pulmonary nodules (median 4, range 2-6), with or without cavitation were present in all patients. RTX induced initial B cell depletion (<5 cells/μL) in all patients but re-population was observed in 3 patients. Repeated RTX treatment in these 3 and persistent B cell depletion in the whole cohort was associated with further significant radiological improvement. Radiographic scoring at each time interval showed reduction in both number of nodules (P =  <0.0001) and largest nodule diameter (P =  <0.0001) in all patients for at least 18 months following B cell depletion. In summary, RTX therapy induces resolution of pulmonary granulomatous inflammation in GPA following prolonged B cell depletion.

Surface levels of CD20 determine anti-CD20 antibodies mediated cell death in vitro

Background

The sensitivity of human Burkitt's lymphoma cells to rituximab (Rtx) and tositumomab (Tst) was assessed on cells expressing different levels of CD20 on surface. Cells that harbor low CD20 levels may resists against therapeutics response to CD20-specific antibodies. We postulated that, radiation-induced modulation of CD20 surface levels may play a crucial and central role in determining the relative efficacy of rituximab and tositumomab in treating Burkitt's lymphoma disease. Here, we examined the γ-radiation-induced CD20 expression in the Burkitt lymphoma cell line ‘Daudi’ and the relation of differential levels of CD20 with anti-CD20 mAbs mediated cell death.

Methodology

In this study we examined kinetics of CD20 expression following sub lethal doses ofγ-radiation to Daudi cells and thereafter anti-CD20 mAbs (rituximab and tositumomab) were added in cell suspensions. The correlation of kinetics of CD20 expression and cells treated with anti-CD20 mAbs/or corresponding isotype Abs with special reference to changes in mitochondrial membrane potential and reactive oxygen species generation was also examined. Further, we also investigated the efficacy of anti-CD20 mAbs and possible induction of cell death in relation to levels of CD20 cell surface expression.

Conclusion

This report provides evidence that CD20 expression can be induced by exposure of cells to γ-radiation. In addition, these findings demonstrated that the efficacy of anti-CD20 mAbs is dependent on the surface levels of CD20. Based on these findings, we hypothesized (i) irradiation just prior to immunotherapy may provide new treatment options even in aggressive B cell tumors, which are resistant to current therapies in vivo (ii) The efficacy of induction of apoptosis varies with type of monoclonal antibodies in vitro.

Immunotherapy for Graves' ophthalmopathy

PURPOSE OF REVIEW

In recent years, immunosuppressive therapy, as an alternative to corticosteroids, has been proposed as novel agents which target the various antigens involved in the pathogenesis of Graves' ophthalmopathy. Although the lack of randomized and controlled studies suggests caution in generalizing results, some data show interesting results.

RECENT FINDINGS

Potential targets for immune therapy in Graves' ophthalmopathy are the antigens expressed on the target organ of inflammation, namely the receptor and the insulin growth factor -1 receptor on fibroblasts, inflammatory cytokines, and B and T cells. The most promising results are observed with small thyroid stimulating hormone receptor molecules interacting with the receptor on thyrocytes and fibroblasts and with the anti-IGF-1 receptor antibody teprotumumab. A recent open study with tocilizumab, an anti-soluble interleukin-6 receptor, has shown inactivation of Graves' ophthalmopathy. Consistent reports on the efficacy of rituximab will have to be confirmed by randomized controlled trials, which are now in progress.

SUMMARY

Current clinical practice for Graves' ophthalmopathy will greatly benefit from the availability of immunosuppressors that act as disease-modifying drugs, as compared to steroids, the current standard treatment for Graves' ophthalmopathy. Rituximab seems to be a good candidate, as preliminary results from ongoing randomized trials suggest good efficacy with a relative well tolerated profile.

Comparison of the anti-prion mechanism of four different anti-prion compounds, anti-PrP monoclonal antibody 44B1, pentosan polysulfate, chlorpromazine, and U18666A, in prion-infected mouse neuroblastoma cells

Molecules that inhibit the formation of an abnormal isoform of prion protein (PrP^Sc) in prion-infected cells are candidate therapeutic agents for prion diseases. Understanding how these molecules inhibit PrP^Sc formation provides logical basis for proper evaluation of their therapeutic potential. In this study, we extensively analyzed the effects of the anti-PrP monoclonal antibody (mAb) 44B1, pentosan polysulfate (PPS), chlorpromazine (CPZ) and U18666A on the intracellular dynamics of a cellular isoform of prion protein (PrP^C) and PrP^Sc in prion-infected mouse neuroblastoma cells to re-evaluate the effects of those agents. MAb 44B1 and PPS rapidly reduced PrP^Sc levels without altering intracellular distribution of PrP^Sc. PPS did not change the distribution and levels of PrP^C, whereas mAb 44B1 appeared to inhibit the trafficking of cell surface PrP^C to organelles in the endocytic-recycling pathway that are thought to be one of the sites for PrP^Sc formation. In contrast, CPZ and U18666A initiated the redistribution of PrP^Sc from organelles in the endocytic-recycling pathway to late endosomes/lysosomes without apparent changes in the distribution of PrP^C. The inhibition of lysosomal function by monensin or bafilomycin A1 after the occurrence of PrP^Sc redistribution by CPZ or U18666A partly antagonized PrP^Sc degradation, suggesting that the transfer of PrP^Sc to late endosomes/lysosomes, possibly via alteration of the membrane trafficking machinery of cells, leads to PrP^Sc degradation. This study revealed that precise analysis of the intracellular dynamics of PrP^C and PrP^Sc provides important information for understanding the mechanism of anti-prion agents.

From synovial tissue to peripheral blood: myeloid related protein 8/14 is a sensitive biomarker for effective treatment in early drug development in patients with rheumatoid arthritis

Objective

The change in number of CD68-positive sublining macrophages in serial synovial biopsies has been successfully used to discriminate on the group level between effective and ineffective treatment during early drug development in rheumatoid arthritis (RA) patients. Measurement of a soluble biomarker would clearly have practical advantages. Therefore, we investigated the sensitivity to change of myeloid related protein (MRP)8/14 in serum.

Methods

139 RA patients who received known effective biologics (infliximab, adalimumab and rituximab) and 28 RA patients who received placebo/ineffective therapies were included. MRP8/14 levels were analyzed in baseline and follow-up serum samples and the standardized response mean (SRM) was calculated to determine the sensitivity to change of MRP8/14 in comparison to C-reactive protein (CRP) levels and the disease activity score evaluated in 28 joints (DAS28).

Results

In patients treated with effective treatment, the SRM for MRP8/14 was moderate (0.56), but in patients treated with placebo/ineffective treatment the SRM was 0.06, suggesting that this biomarker is perhaps not susceptible to placebo effects in proof-of-concept studies of relatively short duration. In contrast, the SRM for DAS28 was high for effective treatment (1.07), but also moderate for ineffective treatment (0.58), representing the placebo effect. The SRM for CRP was low in the effective (0.33) and ineffective (0.23) treatment groups.

Conclusion

These data support the notion that quantification of changes in MRP8/14 serum levels could be used to predict potential efficacy of novel antirheumatic drugs in an early stage of drug development. A positive result would support the rationale for larger, conventional clinical trials to determine whether the effects are clinically relevant.

Rituximab modulates IL-17 expression in the salivary glands of patients with primary Sjögren's syndrome

OBJECTIVE

The aim of this study was to evaluate the role of rituximab (RTX) in modulating the expression of the IL-17/IL-23 pathway in the salivary glands (SGs) of patients with primary SS (pSS).

METHODS

Consecutive SG biopsies were obtained from 15 patients with pSS before and after 1 year of RTX therapy. The SG expression of IL-17, IL-23p19 and p-STAT3 was evaluated by immunohistochemistry at baseline and after RTX therapy. The role of mast cells in pSS patients in modulating the Th17 response and the immunologic effect of RTX on mast cells were also studied in in vitro experiments.

RESULTS

IL-17 was overexpressed in the SGs of patients with pSS mainly by infiltrating T cells and mast cells. After RTX therapy, the SG expression of IL-17, but not of IL-23p19 and p-STAT3, was significantly reduced and was accompanied by the depletion of tissue mast cells. In in vitro experiments with heterologous peripheral lymphocytes RTX significantly induced the apoptosis of isolated mast cells. Finally, mast cells isolated from peripheral blood mononuclear cells of pSS patients in vitro significantly increased Th17 lymphocytes.

CONCLUSION

RTX acts on pSS patients by globally reducing the expression of IL-17 and specifically inducing a pronounced apoptotic depletion of mast cells.

Differential intracellular signalling properties of the growth hormone receptor induced by the activation of an anti-GHR antibody

A series of studies have reported that anti-GHR antibody can function as a GHR agonist and may serve as an attractive tool for studying the mechanisms of GHR activation. However, to date, there is relatively little information about intracellular signalling triggered by anti-GHR antibody. Therefore, in this work, we have developed a panel of monoclonal antibodies to GHBP, among which one Mab, termed CG-172, was selected for further characterisation because of its signalling properties. The results from FACS assays, receptor binding and immunoprecipitation assays and western blotting demonstrated that CG-172 specifically binds to GHR expressed on target cells. Subsequently, epitope mapping studies that used receptor binding analysis showed that CG-172 specifically binds subdomain 1 of GHR ECD. We next examined the resulting signal transduction pathways triggered by this antibody in CHO-GHR638 cells and rat hepatocytes. We found that CG-172 can activate JAK2, AKT, ERK1/2 and STAT1/3 but not STAT5. The phosphorylation kinetics of STAT1/3, AKT and ERK1/2 induced by either GH or CG-172 were analysed in dose-response and time course experiments. Our observations demonstrated that an anti-GHR monoclonal antibody (CG-172) can serve as an attractive tool to study the mechanism(s) of GHR-mediated intracellular signalling pathways and may lead to the production of signal-specific molecules that are capable of inducing different biochemical responses.

Anti-CD22/CD20 Bispecific antibody with enhanced trogocytosis for treatment of Lupus

The humanized anti-CD22 antibody, epratuzumab, has demonstrated therapeutic activity in clinical trials of lymphoma, leukemia and autoimmune diseases, treating currently over 1500 cases of non-Hodgkin lymphoma, acute lymphoblastic leukemias, Waldenström's macroglobulinemia, Sjögren's syndrome, and systemic lupus erythematosus. Because epratuzumab reduces on average only 35% of circulating B cells in patients, and has minimal antibody-dependent cellular cytotoxicity and negligible complement-dependent cytotoxicity when evaluated in vitro, its therapeutic activity may not result completely from B-cell depletion. We reported recently that epratuzumab mediates Fc/FcR-dependent membrane transfer from B cells to effector cells via trogocytosis, resulting in a substantial reduction of multiple BCR modulators, including CD22, CD19, CD21, and CD79b, as well as key cell adhesion molecules, including CD44, CD62L, and β7 integrin, on the surface of B cells in peripheral blood mononuclear cells obtained from normal donors or SLE patients. Rituximab has clinical activity in lupus, but failed to achieve primary endpoints in a Phase III trial. This is the first study of trogocytosis mediated by bispecific antibodies targeting neighboring cell-surface proteins, CD22, CD20, and CD19, as demonstrated by flow cytometry and immunofluorescence microscopy. We show that, compared to epratuzumab, a bispecific hexavalent antibody comprising epratuzumab and veltuzumab (humanized anti-CD20 mAb) exhibits enhanced trogocytosis resulting in major reductions in B-cell surface levels of CD19, CD20, CD21, CD22, CD79b, CD44, CD62L and β7-integrin, and with considerably less immunocompromising B-cell depletion that would result with anti-CD20 mAbs such as veltuzumab or rituximab, given either alone or in combination with epratuzumab. A CD22/CD19 bispecific hexavalent antibody, which exhibited enhanced trogocytosis of some antigens and minimal B-cell depletion, may also be therapeutically useful. The bispecific antibody is a candidate for improved treatment of lupus and other autoimmune diseases, offering advantages over administration of the two parental antibodies in combination.

Simultaneous assessment of rotavirus-specific memory B cells and serological memory after B cell depletion therapy with rituximab

The mechanisms that contribute to the maintenance of serological memory are still unclear. Rotavirus (RV) memory B cells (mBc) are enriched in IgM⁺ and CD27^- subpopulations, which are associated with autoimmune diseases pathogenesis. In patients with autoimmune diseases treated with Rituximab (RTX), some autoantibodies (auto-Abs) decrease after treatment, but other auto-Abs and pathogen-specific IgG Abs remain unchanged. Thus, maintenance of autoimmune and pathogen-specific serological memory may depend on the type of antigen and/or Ab isotype evaluated. Antigen-specific mBc and antigen-specific Abs of different isotypes have not been simultaneously assessed in patients after RTX treatment. To study the relationship between mBc subpopulations and serological memory we characterized total, RV- and tetanus toxoid (TT)-specific mBc by flow cytometry in patients with autoimmune diseases before and after treatment with RTX. We also measured total, RV- and TT-Abs, and some auto-Abs by kinetic nephelometry, ELISA, and EliA tests, respectively. Minor differences were observed between the relative frequencies of RV-mBc in healthy controls and patients with autoimmune disease. After RTX treatment, naïve Bc and total, RV- and TT-specific mBc [IgM⁺, switched (IgA⁺/IgG⁺), IgM⁺ only, IgD⁺ only, and CD27^- (IgA⁺/IgG⁺/IgM⁺)] were significantly diminished. An important decrease in total plasma IgM and minor decreases in total IgG and IgA levels were also observed. IgM rheumatoid factor, IgG anti-CCP, and IgG anti-dsDNA were significantly diminished. In contrast, RV-IgA, RV-IgG and RV-IgG₁, and TT-IgG titers remained stable. In conclusion, in patients with autoimmunity, serological memory against RV and TT seem to be maintained by long-lived plasma cells, unaffected by RTX, and an important proportion of total IgM and serological memory against some auto-antigens seem to be maintained by short-lived plasma cells, dependent on mBc precursors depleted by RTX.

Coinhibitory receptor PD-1H preferentially suppresses CD4⁺ T cell-mediated immunity

T cell activation is regulated by the interactions of surface receptors with stimulatory and inhibitory ligands. Programmed death-1 homolog (PD-1H, also called VISTA) is a member of the CD28 family of proteins and has been shown to act as a coinhibitory ligand on APCs that suppress T cell responses. Here, we determined that PD-1H functions as a coinhibitory receptor for CD4⁺ T cells. CD4⁺ T cells in mice lacking PD-1H exhibited a dramatically increased response to antigen stimulation. Furthermore, delivery of a PD-1H-specific agonist mAb directly inhibited CD4⁺ T cell activation both in vitro and in vivo, validating a coinhibitory function of PD-1H. In a murine model of acute hepatitis, administration of a PD-1H agonist mAb suppressed CD4⁺ T cell-mediated acute inflammation. PD-1H-deficient animals were highly resistant to tumor induction in a murine brain glioma model, and depletion of CD4⁺ T cells, but not CD8⁺ T cells, promoted tumor formation. Together, our findings suggest that PD-1H has potential as a target of immune modulation in the treatment of human inflammation and malignancies.

A neutralizing anti-gH/gL monoclonal antibody is protective in the guinea pig model of congenital CMV infection

Human cytomegalovirus (HCMV) is the most common cause of congenital virus infection. Congenital HCMV infection occurs in 0.2–1% of all births, and causes birth defects and developmental abnormalities, including sensorineural hearing loss and developmental delay. Several key studies have established the guinea pig as a tractable model for the study of congenital HCMV infection and have shown that polyclonal antibodies can be protective [1]–[3]. In this study, we demonstrate that an anti-guinea pig CMV (GPCMV) glycoprotein H/glycoprotein L neutralizing monoclonal antibody protects against fetal infection and loss in the guinea pig. Furthermore, we have delineated the kinetics of GPCMV congenital infection, from maternal infection (salivary glands, seroconversion, placenta) to fetal infection (fetus and amniotic fluid). Our studies support the hypothesis that a neutralizing monoclonal antibody targeting an envelope GPCMV glycoprotein can protect the fetus from infection and may shed light on the therapeutic intervention of HCMV congenital infection in humans.

Human cytomegalovirus (HCMV) is the most common cause of congenital virus infection and causes developmental abnormalities, including hearing loss and developmental delay. Although there is no therapy for congenital HCMV disease, there is evidence from both human and animal studies that antibodies can have efficacy in this setting. Such studies have focused exclusively on polyclonal antibodies, in which the targets of protective antibodies are unknown. Guinea pigs have been used as a model of human maternal fetal transmission of infection because of similarities in placental anatomy between human and guinea pig. Furthermore, guinea pig CMV (GPCMV) has been demonstrated to cross the placenta and cause fetal infection and loss, similar to the effects of infection with HCMV. However, the kinetics of maternal and fetal infection in this model has not been carefully investigated. In this work, we have delineated the kinetics of maternal to fetal infection and found that congenital infection is rapid following maternal infection. Importantly, we demonstrate that a monoclonal antibody against a protein critical for viral entry protects pregnant guinea pigs against fetal infection. Thus, our studies may be informative for development of a therapeutic intervention to treat congenital HCMV infection in humans.

Interleukin-10 producing-B cells and their association with responsiveness to rituximab in myasthenia gravis

INTRODUCTION

A subset of regulatory B cells in humans and mice has been defined functionally by their ability to produce interleukin (IL)-10. We characterized IL-10-producing B (B10) cells in myasthenia gravis (MG) patients and correlated them with disease activity and responsiveness to rituximab therapy.

METHODS

Frequencies of B10 cells from MG patients and healthy controls were monitored by fluorescence-activated cell sorting (FACS).

RESULTS

MG patients had fewer B10 cells than controls, which was associated with more severe disease status. Moreover, patients who responded well to rituximab therapy exhibited rapid repopulation of B10 cells, whereas in patients who did not respond well to rituximab, B10 cell repopulation was delayed. The kinetics of B10 cells were related to the responsiveness to rituximab in MG.

CONCLUSIONS

We have characterized a specific subset of B10 cells in MG patients which may serve as a marker for disease activity and responsiveness to immune therapy.

IL-12 directs further maturation of ex vivo differentiated NK cells with improved therapeutic potential

The possibility to modulate ex vivo human NK cell differentiation towards specific phenotypes will contribute to a better understanding of NK cell differentiation and facilitate tailored production of NK cells for immunotherapy. In this study, we show that addition of a specific low dose of IL-12 to an ex vivo NK cell differentiation system from cord blood CD34(+) stem cells will result in significantly increased proportions of cells with expression of CD62L as well as KIRs and CD16 which are preferentially expressed on mature CD56(dim) peripheral blood NK cells. In addition, the cells displayed decreased expression of receptors such as CCR6 and CXCR3, which are typically expressed to a lower extent by CD56(dim) than CD56(bright) peripheral blood NK cells. The increased number of CD62L and KIR positive cells prevailed in a population of CD33(+)NKG2A(+) NK cells, supporting that maturation occurs via this subtype. Among a series of transcription factors tested we found Gata3 and TOX to be significantly downregulated, whereas ID3 was upregulated in the IL-12-modulated ex vivo NK cells, implicating these factors in the observed changes. Importantly, the cells differentiated in the presence of IL-12 showed enhanced cytokine production and cytolytic activity against MHC class I negative and positive targets. Moreover, in line with the enhanced CD16 expression, these cells exhibited improved antibody-dependent cellular cytotoxicity for B-cell leukemia target cells in the presence of the clinically applied antibody rituximab. Altogether, these data provide evidence that IL-12 directs human ex vivo NK cell differentiation towards more mature NK cells with improved properties for potential cancer therapies.

Role of B lymphocytes in the pathogenesis of type 1 diabetes

Though type 1 diabetes (T1D) is considered a T cell-mediated autoimmune disorder, recent evidence indicates that B cells play a critical role in disease. This conclusion is based in part on the success of anti-CD20 (rituximab) therapy, which by broadly depleting B cells delays disease progression in non-obese diabetic (NOD) mice and new-onset patients. B cell receptor (BCR) specificity to islet autoantigen is key. NOD mice whose B cell repertoire is biased toward insulin reactivity show increased disease development, while bias away from insulin reactivity largely prevents disease. Although the operative disease-promoting B cell effector function remains undefined, islet-antigen reactive B cells function in antigen presentation to diabetogenic CD4 T cells. Other studies implicate B cells in antigen presentation to CD8 T cells. B cell participation in TID appears predicated on faulty B cell tolerance. Here, we review extant findings implicating B cells in T1D in mice and men.

[The quality of life in patients with rheumatoid arthritis treated with rituximab]

The aim of the work was to assess the quality of life in patients with rheumatoid arthritis treated with rituximab in combination with methotrexate or methotrexate monotherapy. The statistically significant improvement of quality of life in both groups 12 months after onset of the treatment was roughly identical. Rutiximab was prescribed after ineffective treatment with TNF-α inhibitors.

[Chronic lymphocytic leukemia accompanied by renal failure]

AIM

To evaluate the efficiency and safety of monotherapy with bendamustine (B) and therapy with B in combination with rituximab (B + R) in patients with chronic lymphocytic leukemia (CLL) accompanied by renal failure (RF).

SUBJECTS AND METHODS

The prospective pilot study included 8 patients (6 men, 2 women) with CLL concurrent with RF. The patients' median age was 63 years (51-77 years). The Binet classification stage of CLL corresponded to B in 2 cases and C in 6. The mean (± standard error) pretreatment concentration of creatinine was 218 ± 92 μmol/l and the glomerular filtration rate (GFR) was 33 ± 20 ml/min. The efficiency of monotherapy with B (n=5) and combination therapy with B + R (n=3) was evaluated. In progressive CLL, therapy was performed in specific treatment-naïve patients (n = 5) and in pretreated patients refractory to alkylating agents (cyclophosphan, chlorambucil) (n = 3). A total of cycles of B and B + R were carried out.

RESULTS

After B monotherapy, one of the 5 cases achieved a complete remission, 3 a partial remission, and 1 a nodular partial remission. Three patients developed recurrence. In the B monotherapy group, the cumulative risk of recurrence was 70% at a median follow-up of 22 months and at a maximum follow-up of 27 months. In the B + R therapy group, all the 3 patients achieved a complete remission. The median follow-up was 7 months; the maximum follow-up was 1 year. There were no deaths or recurrences. During B monotherapy and B + R combination therapy, there was improved kidney function: the mean concentration of creatinine decreased from 218 ± 92 to 140 ± 57 μmol/l (p < 0.05); GFR increased from 33 ± 20.0 to 54 ± 25 ml/min; the mean increment was 20 ml/min (p < 0.01). Mild and moderate anemia and thrombocytopenia were most common during B and B + R therapies. Neutropenia with mild infection complications, as well as nonhematologic complications were detected in some cases. The drugs were observed to have no nephrotoxic effects.

CONCLUSION

The performed pilot prospective indicated that the B + R combination therapy was effective in patients with RF-associated CLL. No toxic effect of B on kidney function was seen. During B therapy, there was better kidney function manifesting itself as a statistically and clinically important decrease in creatinine concentrations and a statistically and clinically important increase in GFR as compared to the baseline values.