The safety and efficacy of biologic agents in treatment of systemic lupus erythematosus: A network meta-analysis.

OBJECTIVE: Previous studies have shown that biologic agents out of the nine medicines might be beneficial for the treatment of SLE. The aim of this study was to evaluate the most effective medication of six biologic agents in treatment of SLE using network meta-analysis (NMA). The performance of these processes is ranked according to the results of this analysis. METHODS: Multiple databases including PubMed, EMBASE and Cochrane Library was used to identify applicable articles and collect relevant data to analyzed by using STATA (13.0) software. The papers included in this study were divided into control group (placebo) and observation group (one of the six medicines). RESULTS: A total of 21 eligible RCTs of biologic agents were identified, a total of 995 papers were included, and the results showed that the belimumab had the highest probability of being the most clinically efficacious intervention, with a surface under the cumulative ranking (SUCRA) curve of 75.0, was significantly superior (P < 0.05) to placebo alone. The blisibimod was the worst, with a SUCRA value of 29.4. The other biologic agents (atacicept, blisibimod, epratuzumab, rituximab, tabalumab) were insignificantly superior (P > 0.05) to placebo alone. CONCLUSIONS: Belimumab had the highest probability of being the best treatment for SLE compared with the other biologic agents (atacicept, blisibimod, epratuzumab, rituximab, tabalumab). The other biologic agents indicated an insignificant difference in efficacy for the treatment of SLE compared with placebo.

Delayed diagnosis of ankylosing spondylitis in a Japanese population.

OBJECTIVES: This study was conducted to evaluate the period from symptom onset to diagnosis of ankylosing spondylitis (AS) in Japanese patients and to examine possible reasons for delayed diagnosis. METHODS: Seventy-two consecutive patients with AS were studied. Diagnostic delay was defined as the gap between the first spondyloarthropathic symptom and diagnosis of AS according to the modified New York criteria. RESULTS: The mean patient ages at disease onset and diagnosis were 25.6 ± 11.3 and 33.3 ± 13.2 years old, respectively, resulting in diagnostic delay of 6.7 years. The number of medical institutions to which patients were referred before diagnosis was 2.4, and orthopedic surgeons were most commonly visited (62%). Non-specific low back pain or lumbar spondylitis (33%) and degenerative arthritis (28%) were the primary diagnoses preceding that of AS. Absence of articular symptoms significantly correlated with diagnostic delay. The patients with disease onset on year 2000 or later had significantly shorter periods until diagnosis than those before 2000 (3.6 vs. 7.5 years). CONCLUSIONS: The present study showed a marked diagnostic delay among Japanese patients with AS. Although it has been improved, continuing medical education focusing on inflammatory back pain in adolescent is required for early diagnosis of AS.

Safety, pharmacokinetics, and pharmacodynamics of epratuzumab in Japanese patients with moderate-to-severe systemic lupus erythematosus: Results from a phase 1/2 randomized study.

OBJECTIVES: This 12-week, randomized, double-blind, placebo-controlled, multicenter phase 1/2 study (NCT01449071) assessed the safety, pharmacokinetics, and pharmacodynamics of epratuzumab in Japanese patients with moderate-to-severe systemic lupus erythematosus despite standard of care. METHODS: Twenty patients were randomized 1:1:1:1:1 to placebo or one of four epratuzumab dose regimens (100 mg every other week [Q2W], 400 mg Q2W, 600 mg every week [QW], or 1200 mg Q2W) administered during an initial 4-week dosing period. Adverse events (AEs), pharmacokinetics and pharmacodynamics were assessed. RESULTS: Nineteen of 20 patients completed the study. All placebo patients and 13 of 16 epratuzumab patients reported ≥1 AE, 2 of 16 epratuzumab patients reported a serious AE. C(max) and AUC(τ) increased proportionally with dose after first and last infusion, t(1/2) was similar across groups (∼13 days). Epratuzumab treatment was associated with decreased CD22 mean fluorescence intensity in total B cells (CD19(+)CD22(+)) and unswitched memory B cells (CD19(+)IgD(+)CD27(+)). Small-to-moderate decreases were observed in total B cell (CD20(+)) count. CONCLUSIONS: Epratuzumab was well-tolerated, with no new safety signals identified. The pharmacokinetics appeared linear after first and last infusions. Treatment with epratuzumab was associated with CD22 downregulation and with small-to-moderate decreases in total B cell count.

Biologic treatment in Sjögren's syndrome.

SS is a chronic systemic autoimmune disease characterized by decreased exocrine gland function. A variety of other disease manifestations may also be present, including general constitutional symptoms and extraglandular features. A multidisciplinary approach focused on both local and systemic medical therapies is needed as the disease has a wide clinical spectrum. The current treatment for SS is mainly symptomatic. However, there is evidence that systemic drugs are effective in controlling extraglandular manifestations of the disease. Overall evidence for the role of conventional immunosuppressive therapy is limited. A number of attempts to use biologic therapies have led to variable results. Biologic agents targeting B cells, such as rituximab, epratuzumab and belimumab, have shown promising results, but further studies are needed to validate the findings. Early-phase studies with abatacept and alefacept proved that T cell stimulation inhibition is another potentially effective target for SS treatment. Modulation or inhibition of other targets such as IFN, IL-6 and Toll-like receptor are also currently being investigated. We have summarized the available evidence regarding the efficacy of biologic treatments and discuss other potential therapies targeting pathways or molecules recognized as being involved in the pathogenesis of SS.

Re-induction chemoimmunotherapy with epratuzumab in relapsed acute lymphoblastic leukemia (ALL): Phase II results from Children's Oncology Group (COG) study ADVL04P2.

BACKGROUND: Given the success of immunotherapeutic approaches in hematologic malignancies, the COG designed a phase I/II study to determine whether the addition of epratuzumab (anti-CD22) to an established chemotherapy platform improves rates of second remission (CR2) in pediatric patients with B-lymphoblastic leukemia (B-ALL) and early bone marrow relapse. PROCEDURE: Therapy consisted of three established blocks of re-induction chemotherapy. Epratuzumab (360 mg/m(2)/dose) was combined with chemotherapy on weekly × 4 (B1) and twice weekly × 4 [eight doses] (B2) schedules during the first re-induction block. Remission rates and minimal residual disease (MRD) status were compared to historical rates observed with the identical chemotherapy platform alone. RESULTS: CR2 was achieved in 65 and 66%, of the evaluable B1 (n = 54) and B2 patients (n = 60), respectively; unchanged from that observed historically without epratuzumab. Rates of MRD negativity (<0.01%) were 31% in B1 (P = 0.4128) and 39% in B2 patients (P = 0.1731), compared to 25% in historical controls. The addition of epratuzumab was well tolerated, with a similar toxicity profile to that observed with the re-induction chemotherapy platform regimen alone. CONCLUSIONS: Epratuzumab was well tolerated in combination with re-induction chemotherapy. While CR2 rates were not improved compared to historical controls treated with chemotherapy alone, there was a non-significant trend towards improvement in MRD response with the addition of epratuzumab (twice weekly for eight doses) to re-induction chemotherapy.

SWOG S0910: a phase 2 trial of clofarabine/cytarabine/epratuzumab for relapsed/refractory acute lymphocytic leukaemia.

Precursor B-acute lymphoblastic leukaemias (pre-B ALLs) comprise the majority of ALLs and virtually all blasts express CD22 in the cytoplasm and on the cell surface. In the present study (Southwestern Oncology Group S0910), we evaluated the addition of epratuzumab, a humanized monoclonal antibody against CD22, to the combination of clofarabine and cytarabine in adults with relapsed/refractory pre-B ALL. The response rate [complete remission and complete remission with incomplete count recovery] was 52%, significantly higher than our previous trial with clofarabine/cytarabine alone, where the response rate was 17%. This result is encouraging and suggests a potential benefit to adding epratuzumab to chemotherapy for ALL; however, a randomized trial will be needed to answer this question.

Epratuzumab for patients with moderate to severe flaring SLE: health-related quality of life outcomes and corticosteroid use in the randomized controlled ALLEVIATE trials and extension study SL0006.

OBJECTIVE: To evaluate health-related quality of life (HRQOL) and corticosteroid use in patients with moderate to severely active SLE enrolled in two international, multicentre, randomized controlled trials of epratuzumab (ALLEVIATE-1 and -2) and a long-term extension study (SL0006). METHODS: Ninety ALLEVIATE patients (43% BILAG A, mean BILAG score 13.2) were randomized to receive 360 mg/m(2) (n = 42) or 720 mg/m(2) (n = 11) epratuzumab or placebo (n = 37), plus standard of care, in 12-week cycles. Corticosteroid use, patient and physician global assessments of disease activity (PtGA and PGA) and 36-item Medical Outcomes Survey Short Form (SF-36) results were recorded at baseline and every 4 weeks. Both trials were prematurely discontinued due to a drug supply interruption; patients followed for ≥6 months were analysed. Twenty-nine patients continued in SL0006, with interim analysis at a median exposure of 120 (range 13-184) weeks. RESULTS: At week 12, proportions of patients with a PGA ≥20% above baseline or with a PtGA improvement greater than or equal to the minimum clinically important difference were higher in the epratuzumab arms than the placebo arm. PGA and PtGA improvements were sustained but did not reach statistical significance. At week 24, mean cumulative corticosteroid doses with epratuzumab 360 and 720 mg/m(2) were 1051 and 1973 mg less than placebo (P = 0.034 and 0.081, respectively). At week 48, SF-36 scores approached or exceeded US age- and gender-matched norms in five domains with the 360 mg/m(2) treatment. Improvements were maintained in SL0006 over ∼2 years. CONCLUSION: Epratuzumab treatment produced clinically meaningful and sustained improvements in PGA, PtGA and HRQOL and reductions in corticosteroid doses.

A phase 2 trial of extended induction epratuzumab and rituximab for previously untreated follicular lymphoma: CALGB 50701.

BACKGROUND: Rituximab combined with chemotherapy has improved the survival of previously untreated patients with follicular lymphoma (FL). Nevertheless, many patients neither want nor can tolerate chemotherapy, leading to interest in biological approaches. Epratuzumab is a humanized anti-CD22 monoclonal antibody with efficacy in relapsed FL. Because both rituximab and epratuzumab have single-agent activity in FL, the antibody combination was evaluated as initial treatment of patients with FL. METHODS: Fifty-nine untreated patients with FL received epratuzumab 360 mg/m2 with rituximab 375 mg/m2 weekly for 4 induction doses. This combination was continued as extended induction in weeks 12, 20, 28, and 36. Response assessed by computed tomography was correlated with clinical risk factors, [18F]fluorodeoxyglucose positron emission tomography findings at week 3, Fcγ polymorphisms, immunohistochemical markers, and statin use. RESULTS: Therapy was well-tolerated, with toxicities similar to expected with rituximab monotherapy. Fifty-two (88.2%) evaluable patients responded, including 25 complete responses (42.4%) and 27 partial responses (45.8%). At 3 years follow-up, 60% of patients remain in remission. Follicular Lymphoma International Prognostic Index (FLIPI) risk strongly predicted progression-free survival (P = .022). CONCLUSIONS: The high response rate and prolonged time to progression observed with this antibody combination are comparable to those observed after standard chemoimmunotherapies and further support the development of biologic, nonchemotherapeutic approaches for these patients.

Efficacy and safety of epratuzumab in patients with moderate/severe flaring systemic lupus erythematosus: results from two randomized, double-blind, placebo-controlled, multicentre studies (ALLEVIATE) and follow-up.

OBJECTIVE: To evaluate epratuzumab treatment in patients with moderately-to-severely active SLE in two international, randomized, controlled trials (ALLEVIATE-1 and -2) and an open-label extension study (SL0006). METHODS: Ninety ALLEVIATE patients (43% BILAG A, median BILAG score 12.0) received standard of care plus 10 total doses of placebo (n = 37) or 360 mg/m(2) (n = 42) or 720 mg/m(2) (n = 11) epratuzumab, administered across 12-week cycles for up to 48 weeks, with BILAG assessments every 4 weeks. Patients were followed for ≥ 6 months and their data combined for analysis. The primary endpoint was BILAG response at week 12 (all BILAG A scores reduced to B/C/D and B scores to C/D, no new A and <2 new B scores). Twenty-nine patients continued in SL0006, receiving 12-week cycles of 360 mg/m(2) epratuzumab; this interim analysis was performed at median 120 weeks (range 13-184) of exposure. RESULTS: Both ALLEVIATE trials were discontinued prematurely because of interruption in drug supply. Exploratory pooled analyses found that responses at week 12 were 15/34 (44.1%) and 2/10 (20.0%) for epratuzumab 360 and 720 mg/m(2), respectively, vs 9/30 (30.0%) for placebo. Total BILAG scores were lower in both epratuzumab arms vs placebo at week 48 and at all but two time points. The incidence of adverse events was similar between groups. In SL0006, median total BILAG score was 8.0 (n = 29) at study entry and 7.0 (n = 19) at week 100, with no additional safety signals. CONCLUSION: This initial efficacy and safety profile of epratuzumab supports its continued development for SLE treatment.

BCR-ABL1 molecular remission after 90Y-epratuzumab tetraxetan radioimmunotherapy in CD22+ Ph+ B-ALL: proof of principle.

Although targeted therapies are used increasingly in hematologic malignancies, we are unaware of any prior studies of radioimmunotherapy (RAIT) in B-acute lymphoblastic leukemia (ALL), even though this radiosensitive tumor expresses CD22, potentially a good target for this approach. Here, we report a patient with Philadelphia chromosome-positive B-ALL in third relapse who received RAIT with (90) yttrium ((90) Y)-labeled anti-CD22 epratuzumab tetraxetan. Seven weeks after initiating therapy, the patient achieved a BCR-ABL1 molecular remission documented by RT-qPCR, which is now continuing at 6 months while awaiting an allogeneic hematopoietic stem cell transplant. (90) Y-Epratuzumab tetraxetan may be a promising therapeutic option for CD22(+) B-ALL patients.

Biologics in oral medicine: Sjogren syndrome.

Oral Diseases (2012) doi:10.1111/j.1601-0825.2012.01932.x Biologic therapy has a potential to benefit patients with orofacial manifestations of Sjogren syndrome (SS). The most appropriate use of biologics would appear to be in patients with severe or multisystem features of SS, but their use early in the pathogenesis has the potential to prevent disease progression. Tumour necrosis factor-alpha blockade has not proven effective in SS. B-cell depletion using rituximab has been of benefit, mainly in relation to extraglandular features, and to some extent in relation to hyposalivation where there is still residual salivary function. Rituximab is also effective in the treatment of SS-associated (extrasalivary) lymphomas, although the therapeutic response in salivary lymphoma is poorer. Rituximab is given as a single or periodic intravenous infusion. Potential adverse effects exist, notably infusion reactions and infection, and so a full risk/benefit analysis is indicated for prospective patients. This and clinical use is best performed and monitored in conjunction with rheumatologists with appropriate training and experience in biologic therapies. Further studies of rituximab in SS are ongoing, and newer agents under trial include belimumab.

B cell depletion and inhibition in systemic lupus erythematosus.

INTRODUCTION: Systemic lupus erythematosus (SLE) is characterized by autoantibody expression and aberrant autoreactive B cells contribute to disease progression; therefore, B cell inhibition has been an attractive target for novel therapies. However, after more than two decades of research and over 40 randomized clinical trials, only one such therapy, belimumab, has been approved for use in SLE. AREAS COVERED: In this review, we discuss the evidence for B cell-targeted therapies in SLE and lupus nephritis. Belimumab has been successful in several large clinical trials and is approved in several countries for use in SLE and lupus nephritis. Despite a lack of supporting phase III evidence, rituximab is used off-label in SLE. Several other B cell-targeted therapies have failed to meet their end points in late-stage clinical trials. Successful phase II trials have recently been reported for obinutuzumab and telitacicept with larger confirmatory trials currently underway. EXPERT OPINION: Refinements in pharmaceutical mechanisms of action, trial design, and patient selection have resulted in recent preliminary successes, offering renewed optimism for B-cell targeted therapeutics in SLE management.

Distinct patterns of disease activity over time in patients with active SLE revealed using latent class trajectory models.

BACKGROUND: Systemic lupus erythematosus (SLE) is a heterogeneous systemic autoimmune condition for which there are limited licensed therapies. Clinical trial design is challenging in SLE due at least in part to imperfect outcome measures. Improved understanding of how disease activity changes over time could inform future trial design. The aim of this study was to determine whether distinct trajectories of disease activity over time occur in patients with active SLE within a clinical trial setting and to identify factors associated with these trajectories. METHODS: Latent class trajectory models were fitted to a clinical trial dataset of a monoclonal antibody targeting CD22 (Epratuzumab) in patients with active SLE using the numerical BILAG-2004 score (nBILAG). The baseline characteristics of patients in each class and changes in prednisolone over time were identified. Exploratory PK-PD modelling was used to examine cumulative drug exposure in relation to latent class membership. RESULTS: Five trajectories of disease activity were identified, with 3 principal classes: non-responders (NR), slow responders (SR) and rapid-responders (RR). In both the SR and RR groups, significant changes in disease activity were evident within the first 90 days of the trial. The SR and RR patients had significantly higher baseline disease activity, exposure to epratuzumab and activity in specific BILAG domains, whilst NR had lower steroid use at baseline and less change in steroid dose early in the trial. CONCLUSIONS: Longitudinal nBILAG scores reveal different trajectories of disease activity and may offer advantages over fixed endpoints. Corticosteroid use however remains an important confounder in lupus trials and can influence early response. Changes in disease activity and steroid dose early in the trial were associated with the overall disease activity trajectory, supporting the feasibility of performing adaptive trial designs in SLE.

Emerging B-Cell Therapies in Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a chronic, multisystem, autoimmune disease of unknown etiology, whose hallmark is the production of autoantibodies. B cells are promising targets for novel SLE therapies. In 2011, belimumab (Benlysta®), a fully humanized monoclonal antibody inhibiting B-cell activation and proliferation, was the first medication in 50 years to be approved by the US Food and Drug Administration to treat adult SLE. This review discusses the current experience with B-cell-targeted therapies, including those targeting B-cell-surface antigens (rituximab, ocrelizumab, ofatumumab, obinutuzumab, obexelimab, epratuzumab, daratumumab), B-cell survival factors (belimumab, tabalumab, atacicept, blisibimod), or B-cell intracellular functions (ibrutinib, fenebrutinib, proteasome inhibitors), for the management of SLE. It focuses on ongoing clinical trials and real-world post-marketing use, where available, including their safety profiles, and concludes with our recommendations for B-cell-centric approaches to the management of SLE.

Targeting CD22 for the Treatment of B-Cell Malignancies.

Immunotherapeutic agents play an increasingly important role in the treatment of B-cell malignancies. CD19 and CD20 are common targets for lymphoid malignancies, though patients who relapse have few therapeutic options remaining. CD22 is a cell surface sialoglycoprotein uniquely present on B-cells and regulates B-cell function and proliferation. Thus, it is an appealing therapeutic target for autoimmune disorders and B-cell malignancies. A variety of therapies targeting CD22 have been developed, including monoclonal antibodies, antibody-drug conjugates, radioimmunoconjugates, chimeric antigen receptor T cells, and bispecific antibodies. Here, we review the biology of CD22 and key therapies targeting CD22 in lymphoid malignancies.

Anti-CD22 epratuzumab for systemic lupus erythematosus: A systematic review and meta-analysis of randomized controlled trials.

Systemic lupus erythematosus (SLE) is a remarkable and challenging autoimmune disorder that is characterized by a broad range of clinical manifestations, such as flares and remissions. Recently, the humanized anti-CD22 antibody epratuzumab for SLE has been extensively studied. The aim of the present study was to perform a meta-analysis on the findings of associated randomized controlled trials in order to evaluate the effects of epratuzumab on SLE. Data from publications in PubMed, EMBASE and the Cochrane Library were collected up to March 2017. To calculate the risk ratio or standardized mean differences (SMDs) with 95% confidence intervals (CIs), a random effect model was applied when heterogeneity was significant and a fixed effect model was used when heterogeneity was negligible. All statistical tests were performed using Review Manager 5.3 software. A total of 1,921 participants in 4 studies (5 trials) that met the selection criteria were analyzed in this meta-analysis. Analyses of the BILAG-based Combined Lupus Assessment (BICLA) response and SLE Disease Activity Index 2000 (SLEDA-2K) score revealed that epratuzumab (720-3,600 mg) significantly improved the BICLA response (RR=1.09; 95% CI, 1.04 to 1.14) and decreased the SLEDA-2K score (SMD=-0.31; 95% CI, -0.67 to 0.06; P=0.10). While the British Isles Lupus Assessment Group index score was not significantly altered between the epratuzumab and control groups. For safety analyses, no statistically significant differences were identified between the two groups, which were proved by the pooled results (all P-values >0.05). These findings suggested that epratuzumab may be relatively safe and may have better therapeutic effectiveness than placebo control conditions in patients with SLE.

Epratuzumab for the treatment of systemic lupus erythematosus.

INTRODUCTION: Systemic lupus erythematosus (SLE) is a multi-system autoimmune disease. There are three drugs licensed for the treatment of lupus: corticosteroids, hydroxychloroquine and belimumab. Immunosuppressants such as azathioprine, methotrexate and mycophenolate are also used. Despite these treatments there is still considerable morbidity. New treatments are needed for the management of active lupus. Epratuzumab a humanized IgG1 monoclonal antibody that targets CD22 resulting in selective B cell modulation that has been considered a potential treatment for SLE. Areas covered: Summary of the relevant pathogenesis and disease activity measurements used in SLE patients, current treatments and unmet needs in SLE, pharmacokinetics and pharmacodynamics of epratuzumab therapy, and a summary of the 7 clinical trials that have investigated the efficacy and safety of epratuzumab in SLE. Expert commentary: It is not clear why trials have failed to demonstrate efficacy but high placebo response rates from optimisation of standard of care and a sub-optimal dosing regimen may have played a role. Post-hoc analysis suggested that there may be subgroups that did respond, such as anti-SSA positive patients with features of Sjogren's syndrome. Further research is needed to explore this and other potential sub-groups that might respond.

Epratuzumab and Blinatumomab as Therapeutic Antibodies for Treatment of Pediatric Acute Lymphoblastic Leukemia: Current Status and Future Perspectives.

BACKGROUND: More than 85% of children affected by acute lymphoblastic leukemia (ALL) are successfully treated; however relapse remains a remarkable clinical concern, with 50-60% of relapsing patients facing a fatal outcome. Management of relapsed patients includes standardized intensive risk-adapted regimens based on conventional drugs, and hematopoietic stem cells transplantation for patients with unfavourable features. Biological drugs, in particular the monoclonal antibody epratuzumab and the bi-functional recombinant single chain peptide blinatumomab, have been recently recognized as novel potential agents to be integrated in salvage ALL therapy to further improve rescue outcome. METHODS: A systematic search of peer-reviewed scientific literature and clinical trials in public databases has been carried out. Both clinical and pre-clinical studies have been included to summarize recent evidence on epratuzumab and blinatumomab for salvage ALL therapy. RESULTS: Sixty-two papers and 25 clinical trials were included. Although not all patients responded properly to these agents, their use in relapsed and refractory pediatric ALL seems promising. CONCLUSION: Phase 3 studies have recently begun and more consistent results about epratuzumab and blinatumomab safety and efficacy in comparison to conventional therapies are expected in the next years. Epratuzumab seems safe in the dosing scheme proposed in ALL, but its efficacy over the conventional chemotherapy is still questionable. Blinatumomab has shown promising results in high risk cases such as elder adult patients and conclusive studies on pediatric ALL are needed. Patient inter-individual variability to these agents has not been investigated in depth, but this issue needs to be addressed, in particular for blinatumomab.

Targeting CD22 with the monoclonal antibody epratuzumab modulates human B-cell maturation and cytokine production in response to Toll-like receptor 7 (TLR7) and B-cell receptor (BCR) signaling.

BACKGROUND: Abnormal B-cell activation is implicated in the pathogenesis of autoimmune diseases, including systemic lupus erythematosus (SLE). The B-cell surface molecule CD22, which regulates activation through the B-cell receptor (BCR), is a potential target for inhibiting pathogenic B cells; however, the regulatory functions of CD22 remain poorly understood. In this study, we determined how targeting of CD22 with epratuzumab (Emab), a humanized anti-CD22 IgG1 monoclonal antibody, affects the activation of human B-cell subsets in response to Toll-like receptor 7 (TLR7) and BCR engagement. METHODS: B-cell subsets were isolated from human tonsils and stimulated with F(ab')2 anti-human IgM and/or the TLR7 agonist R848 in the presence of Emab or a human IgG1 isotype control. Changes in mRNA levels of genes associated with B-cell activation and differentiation were analyzed by quantitative PCR. Cytokine production was measured by ELISA. Cell proliferation, survival, and differentiation were assessed by flow cytometry. RESULTS: Pretreatment of phenotypically naïve CD19+CD10-CD27- cells with Emab led to a significant increase in IL-10 expression, and in some but not all patient samples to a reduction of IL-6 production in response to TLR7 stimulation alone or in combination with anti-IgM. Emab selectively inhibited the expression of PRDM1, the gene encoding B-lymphocyte-induced maturation protein 1 (Blimp-1) in activated CD10-CD27- B cells. CD10-CD27-IgD- cells were highly responsive to stimulation through TLR7 as evidenced by the appearance of blasting CD27hiCD38hi cells. Emab significantly inhibited the activation and differentiation of CD10-CD27-IgD- B cells into plasma cells. CONCLUSIONS: Emab can both regulate cytokine expression and block Blimp1-dependent B-cell differentiation, although the effects of Emab may depend on the stage of B-cell development or activation. In addition, Emab inhibits the activation of CD27-IgD- tonsillar cells, which correspond to so-called double-negative memory B cells, known to be increased in SLE patients with more active disease. These data may be relevant to the therapeutic effect of Emab in vivo via modulation of the production of pro-inflammatory and anti-inflammatory cytokines by B cells. Because Blimp-1 is required by B cells to mature into antibody-producing cells, inhibition of Blimp1 may reduce autoantibody production.