Innate and adaptive immune cell interaction drives inflammasome activation and hepatocyte apoptosis in murine liver injury from immune checkpoint inhibitors.

Immune checkpoints (CTLA4 & PD-1) are inhibitory pathways that block aberrant immune activity and maintain self-tolerance. Tumors co-opt these checkpoints to avoid immune destruction. Immune checkpoint inhibitors (ICIs) activate immune cells and restore their tumoricidal potential, making them highly efficacious cancer therapies. However, immunotolerant organs such as the liver depend on these tolerogenic mechanisms, and their disruption with ICI use can trigger the unintended side effect of hepatotoxicity termed immune-mediated liver injury from ICIs (ILICI). Learning how to uncouple ILICI from ICI anti-tumor activity is of paramount clinical importance. We developed a murine model to recapitulate human ILICI using CTLA4+/- mice treated with either combined anti-CTLA4 + anti-PDL1 or IgG1 + IgG2. We tested two forms of antisense oligonucleotides to knockdown caspase-3 in a total liver (parenchymal and non-parenchymal cells) or in a hepatocyte-specific manner. We also employed imaging mass cytometry (IMC), a powerful multiplex modality for immunophenotyping and cell interaction analysis in our model. ICI-treated mice had significant evidence of liver injury. We detected cleaved caspase-3 (cC3), indicating apoptosis was occurring, as well as Nod-like receptor protein 3 (NLRP3) inflammasome activation, but no necroptosis. Total liver knockdown of caspase-3 worsened liver injury, and induced further inflammasome activation, and Gasdermin-D-mediated pyroptosis. Hepatocyte-specific knockdown of caspase-3 reduced liver injury and NLRP3 inflammasome activation. IMC-generated single-cell data for 77,692 cells was used to identify 22 unique phenotypic clusters. Spatial analysis revealed that cC3+ hepatocytes had significantly closer interactions with macrophages, Kupffer cells, and NLRP3hi myeloid cells than other cell types. We also observed zones of three-way interaction between cC3+ hepatocytes, CD8 + T-cells, and macrophages. Our work is the first to identify hepatocyte apoptosis and NLRP3 inflammasome activation as drivers of ILICI. Furthermore, we report that the interplay between adaptive and innate immune cells is critical to hepatocyte apoptosis and ILICI.

Industry Payments to United States Rheumatologist-Authors of Publications in High-Impact Rheumatology Journals.

OBJECTIVE: A skewed percentage of industry payments goes to "key opinion leaders" (KOLs) whose prominence and influence has increased with time. Given that KOL is neither precisely defined nor quantifiable, we turned to the level of industry payments as a surrogate quantifiable metric and assessed the associations between industry payments to US rheumatologists and their authorships of publications in high-impact rheumatology journals. METHODS: Payments to US rheumatologists during the 2015-2020 interval were obtained from the Centers for Medicare and Medicaid Services Open Payments database, and authorships were tallied for calendar year 2021 publications in the four rheumatology journals (Lancet Rheumatol, Nat Rev Rheumatol, Ann Rheum Dis, Arthritis Rheumatol) with the highest 2021 journal impact factors and journal citation indicators. Differences between groups were determined by chi-squared test, unpaired Student's t-test, one-way analysis of variance (ANOVA), Mann-Whitney rank sum test, and Kruskal-Wallis one-way ANOVA on ranks. Correlations were calculated using Spearman rank order. A P value ≤0.05 was considered significant. RESULTS: There were 278 individual US rheumatologists who received industry payments and served as authors of publications in the four high-impact rheumatology journals. Non-research-associated payments to these individuals strongly correlated with research-associated payments. Payments to male US rheumatologists were greater than those to their female counterparts, and payments strongly correlated with the number of publications among male authors but only weakly, and often not significantly, among female authors. CONCLUSION: A substantial fraction of the authorships in calendar year 2021 publications in four high-impact rheumatology journals arose from a very small percentage of all US rheumatologists who had received industry payments during the 2015-2020 interval. Payments to male US rheumatologist-authors were strikingly different from those to female US rheumatologist-authors, and further investigation is needed to explain the glaring difference in payments.

Impaired dynamic X-chromosome inactivation maintenance in T cells is a feature of spontaneous murine SLE that is exacerbated in female-biased models.

OBJECTIVE: Systemic lupus erythematosus (SLE) is a highly female-biased systemic autoimmune disease, but the molecular basis for this female bias remains incompletely elucidated. B and T lymphocytes from patients with SLE and female-biased mouse models of SLE exhibit features of epigenetic dysregulation on the X chromosome which may contribute to this strong female bias. We therefore examined the fidelity of dynamic X-chromosome inactivation maintenance (dXCIm) in the pathogenesis of two murine models of spontaneous lupus-NZM2328 and MRL/lpr-with disparate levels of female-bias to determine whether impaired dXCIm contributes to the female bias of disease. METHODS: CD23+ B cells and CD3+ T cells were purified from age-matched C57BL/6 (B6), MRL/lpr, and NZM2328 male and female mice, activated in vitro, and processed for Xist RNA fluorescence in situ hybridization, H3K27me3 immunofluorescence imaging, qPCR, and RNA sequencing analyses. RESULTS: The dynamic relocalization of Xist RNA and the canonical heterochromatin mark, H3K27me3, to the inactive X chromosome was preserved in CD23+ B cells, but impaired in activated CD3+ T cells from the MRL/lpr model (p < 0.01 vs. B6), and even more impaired in the heavily female-biased NZM2328 model (p < 0.001 vs. B6; p < 0.05 vs. MRL/lpr). RNAseq of activated T cells from NZM2328 mice revealed the female-biased upregulation of 32 X-linked genes distributed broadly across the X chromosome, many of which have roles in immune function. Many genes encoding Xist RNA-interacting proteins were also differentially expressed and predominantly downregulated, which may account for the observed mislocalization of Xist RNA to the inactive X chromosome. CONCLUSIONS: Although evident in T cells from both the MRL/lpr and NZM2328 models of spontaneous SLE, impaired dXCIm is more severe in the heavily female-biased NZM2328 model. The aberrant X-linked gene dosage in female NZM2328 mice may contribute towards the development of female-biased immune responses in SLE-prone hosts. These findings provide important insights into the epigenetic mechanisms contributing to female-biased autoimmunity.

Isoform-specific knockdown of long and intermediate prolactin receptors interferes with evolution of B-cell neoplasms.

Prolactin (PRL) is elevated in B-cell-mediated lymphoproliferative diseases and promotes B-cell survival. Whether PRL or PRL receptors drive the evolution of B-cell malignancies is unknown. We measure changes in B cells after knocking down the pro-proliferative, anti-apoptotic long isoform of the PRL receptor (LFPRLR) in vivo in systemic lupus erythematosus (SLE)- and B-cell lymphoma-prone mouse models, and the long plus intermediate isoforms (LF/IFPRLR) in human B-cell malignancies. To knockdown LF/IFPRLRs without suppressing expression of the counteractive short PRLR isoforms (SFPRLRs), we employ splice-modulating DNA oligomers. In SLE-prone mice, LFPRLR knockdown reduces numbers and proliferation of pathogenic B-cell subsets and lowers the risk of B-cell transformation by downregulating expression of activation-induced cytidine deaminase. LFPRLR knockdown in lymphoma-prone mice reduces B-cell numbers and their expression of BCL2 and TCL1. In overt human B-cell malignancies, LF/IFPRLR knockdown reduces B-cell viability and their MYC and BCL2 expression. Unlike normal B cells, human B-cell malignancies secrete autocrine PRL and often express no SFPRLRs. Neutralization of secreted PRL reduces the viability of B-cell malignancies. Knockdown of LF/IFPRLR reduces the growth of human B-cell malignancies in vitro and in vivo. Thus, LF/IFPRLR knockdown is a highly specific approach to block the evolution of B-cell neoplasms.

Belimumab for the treatment of pediatric patients with lupus nephritis.

INTRODUCTION: The FDA approved the anti-BAFF monoclonal antibody, belimumab, in 2011 for adult systemic lupus erythematosus (SLE), in 2019 for pediatric SLE, in 2020 for adult lupus nephritis (LN), and in 2022 for pediatric LN. AREAS COVERED: We performed a PUBMED database search through November 2022, using 'belimumab and lupus nephritis,' 'belimumab and childhood systemic lupus erythematosus,' 'belimumab and pediatric systemic lupus erythematosus,' and 'belimumab and juvenile systemic lupus erythematosus' as the search phrases. We also vetted pertinent references cited in the papers gleaned from the above search, and we drew from our personal literature collections. EXPERT OPINION: Based on clinical-trials and real-world experience, belimumab is useful and safe in adult SLE and LN. In contrast and despite FDA approval, evidence of effectiveness in pediatric SLE and pediatric LN is very limited. Whereas there was a trend favoring belimumab in the only randomized, controlled trial to date in pediatric SLE, the difference between the belimumab and placebo groups failed to achieve statistical significance. Moreover, there have been no randomized, controlled trials for belimumab in pediatric LN. Based largely on information gleaned from experience in adults, the clinician can cautiously prescribe belimumab to his/her pediatric LN patient and hope for benefit.

Maternal and cord blood BAFF and APRIL levels during pregnancy.

PROBLEM: Dysregulation of factors vital to the survival B cells and/or plasma cells, such as BAFF and APRIL, could be detrimental to a pregnancy. METHOD OF STUDY: Serially collected first-, second-, and third-trimester serum samples were measured for BAFF and APRIL by ELISA from 150 pregnant women (71 healthy + 79 with a chronic medical disease) at a single medical center. Postpartum serum samples were also collected from the majority of these women. Matched third-trimester and cord blood samples were collected from 168 women (86 healthy + 82 with a chronic medical disease). Data were analyzed by chi-square statistic, unpaired t-test, paired t-test, Mann-Whitney rank sum test, Wilcoxon signed rank test, Spearman rank order correlation, and receiver operator characteristic (ROC) curve analyses as appropriate. RESULTS: Maternal serum BAFF levels declined as the pregnancies progressed and rebounded postpartum, whereas serum APRIL levels remained relatively flat throughout pregnancy and postpartum. Cord BAFF and APRIL levels correlated positively with gestation age and were considerably greater than the corresponding maternal third-trimester serum BAFF and APRIL levels, respectively. In women who developed preeclampsia, third-trimester BAFF levels were greater, rather than lower, than their corresponding second-trimester BAFF levels. ROC curve analysis suggested a potential role for third-trimester serum BAFF level as a biomarker of preeclampsia. CONCLUSIONS: BAFF and APRIL are differentially regulated in the mother during and following pregnancy, whereas each is upregulated in the developing fetus. An increase in third-trimester serum BAFF level may portend development of preeclampsia.

B Cell and T Cell Dissimilarities in BAFF-Deficient versus BR3-Deficient C57BL/6 Mice.

BAFF is a potent B cell survival and differentiation factor with three receptors, TACI, BCMA, and BR3. B cells are greatly reduced in BAFF-deficient mice, and among mice deficient in a single BAFF receptor, B cell reduction is characteristic only of BR3-deficient mice. Nevertheless, there may be important differences between BR3-deficient mice, in which interactions between BAFF and only BR3 are abrogated, and BAFF-deficient mice, in which interactions between BAFF and all its receptors are abrogated. We demonstrate that: 1) the numbers of CD19+ cells in C57BL/6 (B6).Baff-/- and B6.Br3-/- mice diverge as the mice age; 2) the distribution of B cell subsets significantly differ between B6.Baff-/- and B6.Br3-/- mice regardless of age or sex; 3) the relationships of CD3+ and CD4+ cells to B cells vastly differ between B6.Baff-/- and B6.Br3-/- mice as a function of age and sex; 4) the numbers and percentages of CD4+Foxp3+ and CD4+CD25+Foxp3+ are greater in B6.Baff-/- mice than in B6.Br3-/- mice; and 5) for any given number of CD19+ cells or CD4+ cells, percentages of Foxp3+ cells and CD4+CD25+Foxp3+ cells are lower in B6.Br3-/- mice than in B6.Baff-/- mice, with proliferation of these cells being greater, and survival being lesser, in B6.Br3-/- mice than in B6.Baff-/- mice. Collectively, these observations raise the possibility that interactions between TACI and/or BCMA and BAFF modulate expression of B cell subsets and Foxp3+ cells and may help explain prior enigmatic observations of autoimmunity and autoimmune disease in mice despite the absence of functional engagement of BR3 by BAFF.

Preferential Expansion of Foxp3+ T Regulatory Cells in CTLA-4-Deficient and CTLA-4-Haploinsufficient C57BL/6 Mice.

Foxp3+ cells and CTLA-4 have been ascribed major roles in downregulating immune responses. To address the relationship between CTLA-4 expression and Foxp3+ cells, we generated littermate CTLA-4-sufficient (Ctla4 +/+), CTLA-4-haploinsufficient (Ctla4 +/-), and CTLA-4-deficient (Ctla4 -/-) Foxp3-gfp knock-in C57BL/6 mice, permitting us to characterize the phenotype of Foxp3+ cells and to test their ex vivo T regulatory (Treg) suppressor activity. CD3+, CD4+, and CD8+ cells, but not CD19+ cells, were markedly expanded in Ctla4 -/- mice compared with Ctla4 +/+ or Ctla4 +/- mice. In Ctla4 -/- mice, the relative expansion of the Foxp3+ population was greater than that of the CD3+, CD4+, or CD8+ populations because of increased survival of Foxp3+ cells. Foxp3+ Treg cells from Ctla4 -/- mice and Foxp3+ Treg cells from Ctla4 +/+ mice exerted identical ex vivo suppressor function. This may be related to differential expression of GITR, CD73, and CD39 on Foxp3+ Treg cells from Ctla4 -/- mice versus that on corresponding cells from littermate Ctla4 +/+ or Ctla4 +/- mice, with GITR and CD39 being upregulated and CD73 being downregulated on Foxp3+ Treg cells from Ctla4 -/- mice. Moreover, CTLA-4 expression in Ctla4 +/+, Ctla4 +/-, and Ctla4 -/- mice correlated with their percentages of Foxp3+ cells, suggesting an important role for CTLA-4 expression in Treg cell homeostasis. This may have vital ramifications for the treatment of patients for whom augmentation of suppressor function would be beneficial (e.g., patients with autoimmune diseases) and for whom diminution of suppressor function would be beneficial (e.g., patients with cancer).

Impact of Belimumab on Organ Damage in Systemic Lupus Erythematosus.

Organ damage is a key determinant of poor long-term prognosis and early death in patients with systemic lupus erythematosus (SLE). Prevention of damage is a key treatment goal of the 2019 update of the European Alliance of Associations for Rheumatology (EULAR) recommendations for SLE management. Belimumab is a monoclonal antibody that inhibits B lymphocyte stimulator (BLyS) and is the only therapy approved for both SLE and lupus nephritis. Here, we review the clinical trial and real-world data on the effects of belimumab on organ damage in adult patients with SLE. Across 4 phase III studies, belimumab in combination with background SLE therapy demonstrated consistent reductions in key drivers of organ damage including disease activity, risk of new severe flares, and glucocorticoid exposure compared to background therapy alone. Long-term belimumab use in SLE also reduced organ damage progression measured by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index, as reported in open-label extension studies, and propensity score-matched comparative analyses to background therapy alone. Results from a clinical trial showed that in patients with active lupus nephritis, belimumab treatment improved renal response, reduced the risk of renal-related events, and impacted features related to kidney damage progression compared to background therapy alone. The decrease of organ damage accumulation observed with belimumab treatment in SLE, including lupus nephritis, suggest a disease-modifying effect.

Reductions in circulating B cell subsets and immunoglobulin G levels with long-term belimumab treatment in patients with SLE.

OBJECTIVE: To examine the long-term changes in circulating B cell subsets and IgG levels at 5+ years of continuous belimumab treatment and their correlations with efficacy and safety measures. METHODS: This was a post hoc analysis of a continuation study (BEL112233; NCT00724867) of eligible US patients who completed the 76-week BLISS-76 Study (BEL110751; NCT00410384), with up to eight calendar-years of follow-up and median (IQR) belimumab exposure of 310 (209, 364) weeks. From week 76, patients initially randomised to intravenous belimumab 1 mg/kg or 10 mg/kg every 4 weeks in BLISS-76 continued to receive the same dose in the continuation study, while those initially randomised to placebo received belimumab 10 mg/kg intravenous every 4 weeks during continuation. All patients continued to receive standard SLE therapy. Biomarker data were collected, and the effects on baseline and early changes (weeks 0-24 after starting belimumab) from baseline in biomarkers on SLE Responder Index (SRI-4) and infection rate were evaluated. RESULTS: Of the 819 patients from BLISS-76, 268 self-selecting patients entered BEL112233. Compared with baseline, B cell subset counts decreased by 40%-99% after 312 weeks (6 years), and serum IgG levels decreased by 28% after 284 weeks. Higher baseline naïve B cell counts were associated with greater SRI-4 response rates (p<0.05), whereas higher baseline SLE subset plasma and short-lived plasma B cell counts were associated with lower SRI-4 response rates (p<0.05). Elevated baseline IgG levels were associated with increased infection rates over the treatment period (p<0.05), and early greater decreases in IgG levels were associated with higher SRI-4 response rates (p<0.05). CONCLUSIONS: Belimumab treatment up to 312 weeks (6 years) resulted in substantial decreases in several circulating B cell subsets and IgG levels. Higher baseline naïve B cell counts and IgG levels were associated with improved SRI-4 response and increased infection rates, respectively.

First-trimester serum BAFF:sFlt-1 ratio as a candidate early biomarker of spontaneous abortion.

PROBLEM: Immunologic, angiogenic, and anti-angiogenic factors are associated with spontaneous abortion (SAB). B cell-activating factor (BAFF), a proliferation-inducing ligand (APRIL), placental growth factor (PlGF), and soluble fms-like tyrosine kinase-1 (sFlt-1) may play a role in SAB and may serve singly or in combination as an early biomarker of SAB. METHOD OF STUDY: In this prospective observational study, serum sFlt-1, PIGF, BAFF, and APRIL levels were measured in the first trimester of pregnancy in a medically diverse group of women and in non-pregnant controls. Associations and discriminative values of first-trimester sFlt-1, PIGF, BAFF, and APRIL levels and the corresponding APRIL:BAFF, BAFF:sFlt-1, and sFlt-1:PlGF ratios with development of SAB were tested. RESULTS: Median serum BAFF level was lower (p = .007) and median serum sFlt-1 level was higher (p < .001), in the first trimester of pregnancy than in non-pregnant controls. SAB developed in 27 of the pregnant women (11.3%), and first-trimester levels of BAFF (but not APRIL) and sFlt-1 (but not PIGF) were associated with SAB. Using optimal cutoffs determined through receiver operating characteristics curves, the best discriminator of SAB was the serum BAFF:sFlt-1 ratio, specifically among non-nulliparous women and women with prior SAB. CONCLUSION: First-trimester serum BAFF:sFlt-1 ratio is a candidate indicator/predictor of SAB among non-nulliparous women and women with prior SAB. If validated through additional studies, then early identification of pregnant women at high risk for SAB through this simple blood test would assist in counseling and facilitate clinical trials of therapeutic interventions.

Novel signatures associated with systemic lupus erythematosus clinical response to IFN-α/-ω inhibition.

OBJECTIVES: We aimed to identify transcriptional gene signatures predictive of clinical response, for pharmacodynamic evaluation, and to provide mechanistic insight into JNJ-55920839, a human IgG1κ neutralizing mAb targeting IFN-α/IFN-ω, in participants with systemic lupus erythematosus (SLE). METHODS: Blood samples were obtained from SLE participants at baseline and up to Day 130, who received six 10 mg/kg IV doses of JNJ-55920839/placebo every 2 weeks. Participants with mild-to-moderate SLE who achieved clinical responses using SLE Disease Activity Index 2000 Responder Index 4-point change were considered responders. Transcriptional signatures from longitudinally collected blood were generated by RNA-Seq; signatures were generated by microarray from baseline blood samples exposed in vitro to JNJ-55920839 versus untreated. RESULTS: Two gene signatures (IFN-I Signaling and Immunoglobulin Immune Response) exhibited pharmacodynamic changes among JNJ-55920839 responders. The Immunoglobulin signature, but not the IFN-I signature, was elevated at baseline in JNJ-55920839 responders. A gene cluster associated with neutrophil-mediated immunity was reduced at baseline in JNJ-55920839 responders, substantiated by lower neutrophil counts in responders. An IFN-I signature was suppressed by JNJ-55920839 in vitro treatment versus untreated blood to a greater extent in responders before in vivo dosing. CONCLUSIONS: These signatures may enable enrichment for treatment responders when using IFN-I-suppressing treatments in SLE.

Filgotinib in combination with methotrexate or as monotherapy versus methotrexate monotherapy in patients with active rheumatoid arthritis and limited or no prior exposure to methotrexate: the phase 3, randomised controlled FINCH 3 trial.

OBJECTIVES: To investigate efficacy and safety of the Janus kinase-1 inhibitor filgotinib in patients with active rheumatoid arthritis (RA) with limited or no prior methotrexate (MTX) exposure. METHODS: This 52-week, phase 3, multicentre, double-blind clinical trial (NCT02886728) evaluated once-daily oral filgotinib in 1252 patients with RA randomised 2:1:1:2 to filgotinib 200 mg with MTX (FIL200 +MTX), filgotinib 100 mg with MTX (FIL100 +MTX), filgotinib 200 mg monotherapy (FIL200), or MTX. The primary endpoint was proportion achieving 20% improvement in American College of Rheumatology criteria (ACR20) at week 24. RESULTS: The primary endpoint was achieved by 81% of patients receiving FIL200+ MTX versus 71% receiving MTX (p<0.001). A significantly greater proportion treated with FIL100+ MTX compared with MTX achieved an ACR20 response (80%, p=0.017) at week 24. Significant improvement in Health Assessment Questionnaire-Disability Index was seen at week 24; least-squares mean change from baseline was -1.0 and -0.94 with FIL200+MTX and FIL100+MTX, respectively, versus -0.81 with MTX (p<0.001, p=0.008, respectively). Significantly higher proportions receiving FIL200+MTX (54%) and FIL100+MTX (43%) achieved DAS28(CRP) <2.6 versus MTX (29%) (p<0.001 for both) at week 24. Hierarchical testing stopped for comparison of ACR20 for FIL200 monotherapy (78%) versus MTX (71%) at week 24 (p=0.058). Adverse event rates through week 52 were comparable between all treatments. CONCLUSIONS: FIL200+MTX and FIL100+MTX both significantly improved signs and symptoms and physical function in patients with active RA and limited or no prior MTX exposure; FIL200 monotherapy did not have a superior ACR20 response rate versus MTX. Filgotinib was well tolerated, with acceptable safety compared with MTX.

Inhibition of B cell activation following in vivo co-engagement of B cell antigen receptor and Fcγ receptor IIb in non-autoimmune-prone and SLE-prone mice.

Engagement of Fcγ receptor IIb (FcγRIIb) suppresses B cell activation and represents a promising target for therapy in autoimmunity. Obexelimab is a non-depleting anti-human CD19 mAb with an Fc region engineered to have high affinity for human FcγRIIb, thereby co-engaging BCR and FcγRIIb. To assess its ability to suppress B cell activation in vivo, we generated non-autoimmune-prone C57BL/6 (B6) and SLE-prone NZM 2328 (NZM) mice in which the human FcγRIIb extracellular domain was knocked into the mouse Fcgr2b locus (B6.hRIIb and NZM.hRIIb mice, respectively, the latter retaining features of SLE). XENP8206, a mAb which bears the same FcγRIIb-enhanced human Fc domain as does obexelimab but which recognizes murine CD19 rather than human CD19, inhibited in vitro BCR-triggered activation of B cells from both B6.hRIIb and NZM.hRIIb mice. Following administration of XENP8206 to B6.hRIIb or NZM.hRIIb mice, B cell numbers in the spleen and lymph nodes remained stable but became hyporesponsive to BCR-triggered activation for at least 14 days. These findings demonstrate proof-of-principle that pharmacologic co-engagement of BCR and human FcγRIIb inhibits B cell activation in non-autoimmune and SLE-prone hosts while preserving B cell numbers. These observations lay a strong foundation for clinical trials in human SLE with agents that co-engage BCR and FcγRIIb. Moreover, B6.hRIIb and NZM.hRIIb should serve as powerful in vivo models in the elucidation of the cellular and molecular underpinnings of the changes induced by BCR/FcγRIIb co-engagement.

Mortality and adverse events of special interest with intravenous belimumab for adults with active, autoantibody-positive systemic lupus erythematosus (BASE): a multicentre, double-blind, randomised, placebo-controlled, phase 4 trial.

BACKGROUND: Belimumab is approved for the treatment of active systemic lupus erythematosus (SLE). Although clinical trials showed a favourable benefit-risk profile, numerical differences in the incidence of mortality and adverse events of special interest (AESIs) have been reported. We assessed the frequency of these events in patients with SLE receiving belimumab or placebo plus standard therapy. METHODS: BASE was a double-blind, randomised, placebo-controlled, phase 4 trial done in 33 countries. Adults with active SLE were randomly assigned (1:1) to receive intravenous belimumab (10 mg/kg) or placebo, plus standard therapy, for 48 weeks. The primary endpoints were incidences of all-cause mortality and AESIs during the on-treatment period (first-to-last study drug dose + 28 days). Safety analyses were done in the as-treated population (patients grouped by actual treatment received >50% of the time). This study was registered with ClinicalTrials.gov (NCT01705977). FINDINGS: Between Nov 27, 2012, and July 28, 2017, we randomly assigned 4018 patients. The as-treated population included 2002 patients in the belimumab group versus 2001 in the placebo group. Ten (0·50%) patients in the belimumab group died versus eight (0·40%) in the placebo group (difference 0·10%, 95% CI -0·31 to 0·51). Incidences were similar in the belimumab and placebo groups for serious infections (75 [3·75%] of 2002 vs 82 [4·10%] of 2001; difference -0·35%, 95% CI -1·55 to 0·85), opportunistic infections and other infections of interest (36 [1·80%] vs 50 [2·50%]; -0·70%, -1·60 to 0·20), non-melanoma skin cancers (4 [0·20%] vs 3 [0·15%]; 0·05%, -0·21 to 0·31) and other malignancies (5 [0·25%] vs 5 [0·25%]; 0·00%, -0·31 to 0·31). A higher proportion of patients in the belimumab group than in the placebo group had infusion and hypersensitivity reactions (8 [0·40%] vs 2 [0·10%]; 0·30%, -0·01 to 0·61), serious depression (7 [0·35%] vs 1 [0·05%]; 0·30%, 0·02 to 0·58), treatment-emergent suicidality (28 [1·42%] of 1972 patients vs 23 [1·16%] of 1986; 0·26%, -0·44 to 0·96), and sponsor-adjudicated serious suicide or self-injury (15 [0·75%] of 1972 patients vs 5 [0·25%] of 1986; post hoc difference 0·50%, 0·06 to 0·94). INTERPRETATION: In line with previously published data, incidences of all-cause mortality and AESIs were similar in patients given belimumab and placebo, except for serious infusion or hypersensitivity reactions, serious depression, treatment-emergent suicidality, and sponsor-adjudicated serious suicide or self-injury events. FUNDING: GSK.

Systemic lupus erythematosus (SLE): emerging therapeutic targets.

INTRODUCTION: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with a heterogeneous clinical presentation whose etiologies are multifactorial. A myriad of genetic, hormonal, immunologic, and environmental factors contribute to its pathogenesis, and its diverse biological basis and phenotypic presentations make development of therapeutics difficult. In the past decade, tens of therapeutic targets with hundreds of individual candidate therapeutics have been investigated. AREAS COVERED: We used a PUBMED database search through April 2020 to review the relevant literature. This review discusses therapeutic targets in the adaptive and innate immune systems, specifically: B cell surface antigens, B cell survival factors, Bruton's tyrosine kinase, costimulators, IL-12/IL-23, the calcineurin pathway, the JAK/STAT pathway, and interferons. EXPERT OPINION: Our ever-improving understanding of SLE pathophysiology in the past decade has allowed us to identify new therapeutic targets. Multiple new drugs are on the horizon that target different elements of the adaptive and innate immune systems. SLE research remains challenging due to the heterogenous clinical presentation of SLE, confounding from background immunosuppressives being taken by SLE patients, animal models that inadequately recapitulate human disease, and imperfect and complicated outcome measures. Despite these limitations, research is promising and ongoing. The search for new therapies that target specific elements of SLE pathophysiology are discussed as well as key findings, pitfalls, and questions surrounding these targets.

Belimumab and Rituximab in Systemic Lupus Erythematosus: A Tale of Two B Cell-Targeting Agents.

Given the centrality of B cells to systemic lupus erythematosus (SLE), it stands to reason that a candidate therapeutic agent that targets B cells could be efficacious. Both rituximab, a monoclonal antibody (mAb) that binds to CD20 on the surface of B cells, and belimumab, a mAb that binds and neutralizes the B cell survival factor BAFF, have been extensively studied for the treatment of SLE. Despite the greater ability of rituximab to deplete B cells than that of belimumab, randomized controlled trials of rituximab in SLE failed to reach their primary clinical endpoints, whereas the primary clinical endpoints were reached in four independent phase-III clinical trials of belimumab in SLE. Accordingly, belimumab has been approved for treatment of SLE, whereas use of rituximab in SLE remains off-label. Nevertheless, several case series of rituximab have pointed to some utility for rituximab in treating SLE. In this review, we provide a concise summary of the factors that led to belimumab's success in SLE as well an analysis of the elements that may have contributed to the lack of success seen in the rituximab randomized controlled trials in SLE.

Circulating TNF-like protein 1A (TL1A) is elevated early in rheumatoid arthritis and depends on TNF.

BACKGROUND: The tumor necrosis factor (TNF) superfamily cytokine TNF-like protein 1A (TL1A) and its receptor DR3 are essential for diverse animal models of autoimmune disease and may be pathogenic in rheumatoid arthritis (RA). However, the relationship of TL1A to disease duration, activity, and response to anti-TNF and other therapies in RA is not clear. METHODS: We measured soluble TL1A in synovial fluid (SF), serum, or plasma from RA first-degree relatives (FDRs) and in early RA and established disease. We measured the effects of anti-TNF and methotrexate (MTX) therapy on circulating TL1A from multiple independent RA treatment trials. We also determined the ability of a blocking anti-TL1A antibody to inhibit clinical disease and articular bone destruction in the murine collagen-induced arthritis (CIA) model of human RA. RESULTS: Soluble TL1A was specifically elevated in the blood and SF of patients with RA compared to patients with other diseases and was elevated early in disease and in at-risk anti-cyclic citrullinated peptide (CCP) (+) first-degree relatives (FDRs). Therapeutic TNF inhibition reduced serum TL1A in both responders and non-responders, whereas TL1A declined following MTX treatment only in responders. In murine CIA, TL1A blockade was clinically efficacious and reduced bone erosions. CONCLUSIONS: TL1A is specifically elevated in RA from early in the disease course and in at-risk FDRs. The decline in TL1A after TNF blockade suggests that TL1A levels may be a useful biomarker for TNF activity in RA. These results support the further investigation of the relationship between TL1A and TNF and TL1A blockade as a potential therapeutic strategy in RA.

Promotion of T Regulatory Cells in Mice by B Cells and BAFF.

In addition to promoting B cell expansion, overexpression of BAFF promotes expansion of T cells, including T regulatory (Treg) cells. To determine the relationships among BAFF, B cells, and Treg cells, a panel of C57BL/6 (B6) congenic mice was tested. Treg cells were disproportionately expanded in mice expressing a Baff transgene (B6.BTg) and were disproportionately contracted in mice deficient in BAFF (B6.Baff-/- ). In vitro suppressor activities of B6 wild-type, B6.BTg, and B6.Baff-/- Treg cells were identical, as was in vitro generation of Treg cells. In vivo proliferation of Treg cells was greatest in B6.BTg mice, whereas in vivo survival of Treg cells was lowest in B6.Baff-/- mice. B cells promoted BAFF-independent Treg cell expansion in vivo, as evidenced by the correlation between B cells and percentages of Treg cells in B6.Baff-/- mice and by the greater percentages of Treg cells in B6.Bcl2Tg mice (which harbor B cells largely independent of BAFF because of expression of a Bcl2 transgene) than in B6 wild-type mice despite the lower serum BAFF levels in the former than in the latter. Experiments with BAFF-deficient B6.Baff-/- Bcl2Tg mice, B cell-deficient B6.µMT mice, BAFF-overexpressing/B cell-deficient B6.BTg.µMT mice, and BAFF-deficient/B cell-deficient B6.Baff-/- µMT mice demonstrated that, in a host that harbors B cells, the effect of BAFF on Treg cells goes beyond its ability to expand the B cell population and is additional to the BAFF-independent effect of B cells on Treg cells. These findings may have considerable relevance to the treatment of B cell-associated autoimmune diseases.

Development of Murine Systemic Lupus Erythematosus in the Absence of BAFF.

OBJECTIVE: To determine whether systemic lupus erythematosus (SLE) can develop in the absence of BAFF in an SLE-prone host. METHODS: Starting with C57BL/6 mice that express a human BCL2 transgene (Tg) in their B cells (thereby rendering B cell survival largely independent of BAFF-triggered signals), we introgressed this Tg into NZM 2328 mice genetically deficient in BAFF (NZM.Baff-/- ) to generate NZM.Baff-/- .Bcl2Tg mice. Expression of human Bcl-2 and lymphocyte profiles were assessed by fluorescence-activated cell sorting, and serologic profiles were determined by enzyme-linked immunosorbent assay. Immunofluorescence and histologic analyses were performed to assess renal immunopathologic features in the mice, and clinical disease was assessed according to the outcomes of severe proteinuria and death. RESULTS: In comparison to their non-Tg NZM.Baff-/- littermates (n ≥ 7), NZM.Baff-/- .Bcl2Tg mice (n ≥ 8) overexpressed Bcl-2 in their B cells and developed significantly increased percentages and numbers of B cells and plasma cells, serum levels of IgG autoantibodies, glomerular deposition of IgG and C3, and severity of glomerular and tubulointerstitial inflammation, culminating in severe proteinuria and death (all P < 0.05 versus NZM.Baff-/- littermates). The time course for development of SLE-like features in NZM.Baff-/- .Bcl2Tg mice was more rapid than has been previously observed in NZM 2328 wild-type mice (median age at death 4.5 months versus 7.5 months). NZM.Baff-/- .Bcl2Tg mice remained responsive to BAFF, since reintroduction of the Baff gene into these mice further accelerated the course of disease (median age at death 3 months). CONCLUSION: The role of BAFF in the development of SLE-like disease may be dispensable as long as B cell survival is preserved via a BAFF-independent pathway. This may help explain the limited and variable clinical success with BAFF antagonists in human SLE. Thus, NZM.Baff-/- .Bcl2Tg mice may serve as a powerful murine model for the study of BAFF-independent SLE.