Obexelimab in Systemic Lupus Erythematosus With Exploration of Response Based on Gene Pathway Co-Expression Patterns: A Double-Blind, Randomized, Placebo-Controlled, Phase 2 Trial.

OBJECTIVE: Obexelimab is an investigational, bifunctional, noncytolytic monoclonal antibody that binds CD19 and FcyRIIb to inhibit B cells, plasmablasts, and plasma cells. This trial evaluated the efficacy and safety of obexelimab in the treatment of patients with systemic lupus erythematosus (SLE). METHODS: During screening, patients with active, non-organ-threatening SLE received corticosteroid injections to ameliorate symptoms while immunosuppressants were withdrawn (≤10 mg/day prednisone equivalent and ≤400 mg/day hydroxychloroquine allowed). Patients with improved disease activity were randomized 1:1 to obexelimab 5 mg/kg intravenously or placebo once every 2 weeks until week 32 or loss of improvement (LOI). RESULTS: In this study, 104 patients were randomized. Analysis of the primary endpoint, proportion of patients reaching week 32 without LOI, used an efficacy-evaluable (EE) population defined as patients who completed the study or withdrew for flare or treatment-related toxicity. This endpoint did not reach statistical significance: 21 of 50 obexelimab-treated patients (42.0%) versus 12 of 42 patients (28.6%) treated with a placebo (P = 0.183). Time to LOI was increased in obexelimab-treated patients versus patients treated with a placebo in the EE (hazard ratio [HR] 0.53, P = 0.025) and intention-to-treat (HR 0.59, P = 0.062) populations. In obexelimab-treated patients, B cells decreased approximately 50%, and trough concentration and inclusion in baseline gene expression clusters with high B cell pathway modules were associated with increased time to LOI. Obexelimab was associated with infusion reactions but was generally safe and well-tolerated. CONCLUSION: Although the primary endpoint was not reached, secondary analysis showed time to LOI was significantly increased in obexelimab-treated patients, and analysis of patient subsets defined by gene expression patterns at baseline suggests a responding subpopulation.

Metopimazine is primarily metabolized by a liver amidase in humans.

Metopimazine (MPZ) is a peripherally restricted, dopamine D2 receptor antagonist used for four decades to treat acute nausea and vomiting. MPZ is currently under clinical investigation for the treatment of gastroparesis (GP). MPZ undergoes high first-pass metabolism that produces metopimazine acid (MPZA), the major circulating metabolite in humans. Despite a long history of use, the enzymes involved in the metabolism of MPZ have not been identified. Here we report a series of studies designed to identify potential MPZ metabolites in vitro, determine their clinical relevance in humans, and elucidate the enzymes responsible for their formation. The findings demonstrated that the formation of MPZA was primarily catalyzed by human liver microsomal amidase. Additionally, human liver cytosolic aldehyde oxidase (AO) catalyzes the formation of MPZA, in vitro, although to a much lesser extent. Neither cytochrome P450 enzymes nor flavin-monooxygenases (FMO) were involved in the formation MPZA, although two minor oxidative pathways were catalyzed by CYP3A4 and CYP2D6 in vitro. Analysis of plasma samples from subjects dosed 60 mg of MPZ verified that these oxidative pathways are very minor and that CYP enzyme involvement was negligible compared to microsomal amidase/hydrolase in overall MPZ metabolism in humans. The metabolism by liver amidase, an enzyme family not well defined in small molecule drug metabolism, with minimal metabolism by CYPs, differentiates this drug from current D2 antagonists used or in development for the treatment of GP.

STRATUS: A Phase II Study of Abituzumab in Patients With Systemic Sclerosis-associated Interstitial Lung Disease.

OBJECTIVE: To investigate the effects of abituzumab in systemic sclerosis-associated interstitial lung disease (SSc-ILD). METHODS: STRATUS was a phase II, double-blind, parallel-group, multicenter trial (ClinicalTrials.gov: NCT02745145). Adults (≤ 75 yrs) with SSc-ILD on stable mycophenolate were randomized (2:2:1) to receive intravenous abituzumab 1500 mg, abituzumab 500 mg, or placebo every 4 weeks for 104 weeks. The primary endpoint was the annual rate of change in absolute forced vital capacity. RESULTS: STRATUS was terminated prematurely due to slow enrollment (n = 75 screened, n = 24 randomized), precluding robust analysis of efficacy. Abituzumab was well tolerated; no new safety signals were detected. CONCLUSION: Further investigation of abituzumab for treatment of SSc-ILD is required.

Effect of Intra-Articular Sprifermin vs Placebo on Femorotibial Joint Cartilage Thickness in Patients With Osteoarthritis: The FORWARD Randomized Clinical Trial.

Importance: Sprifermin is under investigation as a disease-modifying osteoarthritis drug. Objective: To evaluate the effects of sprifermin on changes in total femorotibial joint cartilage thickness in the more symptomatic knee of patients with osteoarthritis. Design, Setting, and Participants: FORWARD (FGF-18 Osteoarthritis Randomized Trial with Administration of Repeated Doses) was a 5-year, dose-finding, multicenter randomized clinical trial conducted at 10 sites. Eligible participants were aged 40 to 85 years with symptomatic, radiographic knee osteoarthritis and Kellgren-Lawrence grade 2 or 3. Enrollment began in July 2013 and ended in May 2014; the last participant visit occurred on May 8, 2017. The primary outcome at 2 years and a follow-up analysis at 3 years are reported. Interventions: Participants were randomized to 1 of 5 groups: intra-articular injections of 100 µg of sprifermin administered every 6 months (n = 110) or every 12 months (n = 110), 30 µg of sprifermin every 6 months (n = 111) or every 12 months (n = 110), or placebo every 6 months (n = 108). Each treatment consisted of weekly injections over 3 weeks. Main Outcomes and Measures: The primary end point was change in total femorotibial joint cartilage thickness measured by quantitative magnetic resonance imaging at 2 years. The secondary end points (of 15 total) included 2-year change from baseline in total Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. The minimal clinically important difference (MCID) is unknown for the primary outcome; for total WOMAC score in patients with hip and knee osteoarthritis, the absolute MCID is 7 U (95% CI, 4 to 10 U) and the percentage MCID is 14% (95% CI, 9% to 18%). Results: Among 549 participants (median age, 65.0 years; 379 female [69.0%]), 474 (86.3%) completed 2-year follow-up. Compared with placebo, the changes from baseline to 2 years in total femorotibial joint cartilage thickness were 0.05 mm (95% CI, 0.03 to 0.07 mm) for 100 µg of sprifermin administered every 6 months; 0.04 mm (95% CI, 0.02 to 0.06 mm) for 100 µg of sprifermin every 12 months; 0.02 mm (95% CI, -0.01 to 0.04 mm) for 30 µg of sprifermin every 6 months; and 0.01 mm (95% CI, -0.01 to 0.03 mm) for 30 µg of sprifermin every 12 months. Compared with placebo, there were no statistically significant differences in mean absolute change from baseline in total WOMAC scores for 100 µg of sprifermin administered every 6 months or every 12 months, or for 30 µg of sprifermin every 6 months or every 12 months. The most frequently reported treatment-emergent adverse event was arthralgia (placebo: n = 46 [43.0%]; 100 µg of sprifermin administered every 6 months: n = 45 [41.3%]; 100 µg of sprifermin every 12 months: n = 50 [45.0%]; 30 µg of sprifermin every 6 months: n = 40 [36.0%]; and 30 µg of sprifermin every 12 months: n = 48 [44.0%]). Conclusions and Relevance: Among participants with symptomatic radiographic knee osteoarthritis, the intra-articular administration of 100 µg of sprifermin every 6 or 12 months vs placebo resulted in an improvement in total femorotibial joint cartilage thickness after 2 years that was statistically significant, but of uncertain clinical importance; there was no significant difference for 30 µg of sprifermin every 6 or 12 months vs placebo. Durability of response also was uncertain. Trial Registration: ClinicalTrials.gov Identifier: NCT01919164.

Ongoing clinical trials and treatment options for patients with systemic sclerosis-associated interstitial lung disease.

SSc is a rare CTD that affects multiple organ systems, resulting in substantial morbidity and mortality. Evidence of interstitial lung disease (ILD) is seen in ∼80% of patients with SSc. Currently there is no approved disease-modifying treatment for ILD and few effective treatment options are available. CYC is included in treatment guidelines, but it has limited efficacy and is associated with toxicity. MMF is becoming the most commonly used medication in clinical practice in North America and the UK, but its use is not universal. Newer agents targeting the pathogenic mechanisms underlying SSc-ILD, including fibrotic and inflammatory pathways, lymphocytes, cell-cell and cell-extracellular membrane interactions, hold promise for better treatment outcomes, including improved lung function, patient-related outcomes and quality of life. Here we review ongoing trials of established and novel agents that are currently recruiting patients with SSc-ILD.

Efficacy and Safety of Atacicept in Patients With Systemic Lupus Erythematosus: Results of a Twenty-Four-Week, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Parallel-Arm, Phase IIb Study.

OBJECTIVE: To evaluate the efficacy and safety of atacicept, an antagonist of B lymphocyte stimulator/APRIL-mediated B cell activation, in patients with systemic lupus erythematosus (SLE). METHODS: ADDRESS II is a 24-week, multicenter, randomized, double-blind, placebo-controlled, parallel-arm, phase IIb study evaluating the safety and efficacy of atacicept in patients with SLE (ClinicalTrials.gov identifier NCT01972568). Patients with active, autoantibody-positive SLE receiving standard therapy were randomized (1:1:1) to receive atacicept (75 mg or 150 mg) or placebo for 24 weeks. The primary end point was the SLE responder index 4 (SRI-4) at week 24. RESULTS: The intent-to-treat (ITT) population included 306 patients. There was a trend toward an improved SRI-4 response rate with atacicept 75 mg (57.8%; adjusted odds ratio [OR] 1.78, P = 0.045) and 150 mg (53.8%; adjusted OR 1.56, P = 0.121) at week 24 as compared with placebo (44.0%) (primary analysis; using the screening visit as baseline). In a prespecified sensitivity analysis using study day 1 as baseline, a significantly larger proportion of patients receiving atacicept 75 mg and 150 mg achieved an SRI-4 response at week 24 compared with placebo. In predefined subpopulations with high levels of disease activity (HDA) at baseline, serologically active disease, or both, statistically significant improvements in the SRI-4 and SRI-6 response rates were seen with atacicept versus placebo. A severe risk of disease flare was reduced with atacicept therapy in both the ITT and the HDA populations. The risks of serious adverse events and serious or severe infection were not increased with atacicept as compared with placebo. CONCLUSION: Atacicept treatment showed evidence of efficacy in SLE, particularly in HDA and serologically active patients. Reductions in disease activity and severe flare were observed with atacicept treatment, with an acceptable safety profile.

Targeting BAFF and APRIL in systemic lupus erythematosus and other antibody-associated diseases.

The B cell-stimulating molecules, BAFF (B cell activating factor) and APRIL (a proliferation-inducing ligand), are critical factors in the maintenance of the B cell pool and humoral immunity. In addition, BAFF and APRIL are involved in the pathogenesis of a number of human autoimmune diseases, with elevated levels of these cytokines detected in the sera of patients with systemic lupus erythematosus (SLE), IgA nephropathy, Sjögren's syndrome, and rheumatoid arthritis. As such, both molecules are rational targets for new therapies in B cell-driven autoimmune diseases, and several inhibitors of BAFF or BAFF and APRIL together have been investigated in clinical trials. These include the BAFF/APRIL dual inhibitor, atacicept, and the BAFF inhibitor, belimumab, which is approved as an add-on therapy for patients with active SLE. Post hoc analyses of these trials indicate that baseline serum levels of BAFF and BAFF/APRIL correlate with treatment response to belimumab and atacicept, respectively, suggesting a role for the two molecules as predictive biomarkers. It will, however, be important to refine future testing to identify active forms of BAFF and APRIL in the circulation, as well as to distinguish between homotrimer and heteromer configurations. In this review, we discuss the rationale for dual BAFF/APRIL inhibition versus single BAFF inhibition in autoimmune disease, by focusing on the similarities and differences between the physiological and pathogenic roles of the two molecules. A summary of the preclinical and clinical data currently available is also presented.

Post Hoc Analysis of the Phase II/III APRIL-SLE Study: Association Between Response to Atacicept and Serum Biomarkers Including BLyS and APRIL.

OBJECTIVE: To assess the relationship between treatment response, baseline biomarker levels, and atacicept exposure in patients with systemic lupus erythematosus (SLE) in the phase II/III APRIL-SLE study. METHODS: We performed a post hoc analysis of patients who received placebo, atacicept 75 mg, or atacicept 150 mg in a randomized, controlled, 52-week trial. Serum levels of BlyS and APRIL were measured at baseline, and serum levels of Ig and the numbers of naive B cells and plasma cells were measured at baseline and during treatment. Atacicept exposure was determined by assessment of the serum trough concentrations throughout the 52-week trial period. Associations between these parameters, treatment response (reduction in British Isles Lupus Assessment Group A or B flare), and infection rates were explored. RESULTS: Recurrent high baseline levels of both BLyS (≥1.6 ng/ml) and APRIL (≥2.2 ng/ml) correlated with a greater treatment response (flare rate 75.7% with placebo, and 50.0% and 32.0% with atacicept 75 mg and atacicept 150 mg, respectively) compared with lower baseline levels of both. Increased atacicept exposure correlated with reduced flare rates (60.5% with placebo; 63.4%, 61.0%, 48.8%, and 29.3% in the 4 quartiles, from lowest to highest atacicept exposure). Greater pharmacodynamic responses (reduced Ig levels and naive B cell and plasma cell numbers) were associated with greater reductions in the flare rate. Infection rates were similar regardless of biomarker levels at baseline or at the time of atacicept exposure. CONCLUSION: These post hoc analyses demonstrate a dose-response relationship between atacicept concentrations, reduced Ig levels, and reduced flare rates and suggest that baseline biomarkers such as elevated serum levels of BLyS and APRIL may help to identify the patients who are most likely to benefit from atacicept treatment.

Atacicept in combination with MMF and corticosteroids in lupus nephritis: results of a prematurely terminated trial.

INTRODUCTION: Atacicept is a soluble, fully human, recombinant fusion protein that inhibits B cell-stimulating factors APRIL (a proliferation-inducing ligand) and BLyS (B-lymphocyte stimulator). The APRIL- LN study aimed to evaluate the efficacy and safety of atacicept in patients with active lupus nephritis (LN), receiving newly initiated corticosteroids (CS) and mycophenolate mofetil (MMF). METHODS: This was a randomized, double-blind, placebo-controlled Phase II/III, 52-week study. At screening (Day -14), patients initiated high-dose CS (the lesser of 0.8 mg/kg/day or 60 mg/day prednisone) and MMF (1 g daily, increased by 1 g/day each week to 3 g daily). From Day 1, atacicept (150 mg, subcutaneously, twice weekly for 4 weeks, then weekly) was initiated with MMF along with a tapered dose of CS. RESULTS: The trial was terminated after the enrollment of six patients, due to an unexpected decline in serum immunoglobulin G (IgG) and the occurrence of serious infections. Efficacy was thus not evaluated. By Day 1, serum IgG levels had declined substantially in patients then randomized to atacicept (n = 4) compared with placebo (n = 2). Patients receiving atacicept also had more severe proteinuria on Day -14 than those on placebo. Lymphocyte counts were low at screening in all patients. IgG decline continued following initiation (Day 1) of atacicept. Three atacicept-treated patients developed serum IgG below the protocol-defined discontinuation threshold of 3 g/l, two of whom developed serious pneumonia. CONCLUSIONS: Future studies are needed to characterize the safety, efficacy, and pharmacodynamic response of atacicept in LN patients. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00573157.

Low over-expression of TNFalpha in the mouse heart increases contractile performance via TNFR1.

TNFalpha is a cytokine wit pleiotropic functions in many organs. In the heart increased TNFalpha levels are not only associated with heart failure, but also, paradoxically, with protection from ischemic damage. To test whether the protective role of TNFalpha in the heart is concentration-dependent, we studied two mouse heart models with low (two- to threefold) over-expression of endogenous TNFalpha: mice deficient in a translational repressor of TNFalpha mRNA, TIA-1(-/-), and mice over-expressing human TNFalpha. Hearts lacking TIA-1 were characterized for their endogenous TNFalpha over-expression during normal Langendorff perfusion. To define which TNFalpha receptor mediates cardiac protection, we also used mice lacking the TNFR1 receptor. Contractile function was assessed in isolated hearts perfused in the isovolumic Langendorff mode during and following global no-flow ischemic stress and in response to varying extracellular [Ca(2+)] to determine their contractile response and Ca(2+) sensitivity. All hearts with low over-expression of TNFalpha, independent of human or murine origin, have improved contractile performance and increased Ca(2+) sensitivity (by 0.2-0.26 pCa). Hearts lacking TNFR1 have contractile performance equal to wild type hearts. Recovery from ischemia was greater in TIA-1(-/-) and was diminished in TNFR1(-/-). Better contractile function in TNFalpha over-expressing hearts is not due to improved cardiac energetics assessed as [ATP] and glucose uptake or to differences in expression of SERCA2a or calmodulin. We suggest that low levels of TNFalpha increase the Ca(2+) sensitivity of the heart via a TNFR1-mediated mechanism.

The tumor necrosis factor-alpha AU-rich element inhibits the stable association of the 40S ribosomal subunit with RNA transcripts.

Tumor necrosis factor-alpha (TNF-alpha) is a potent cytokine that is central to normal immune responses as well as autoimmune inflammatory diseases. The production of TNF-alpha protein is thus tightly regulated at multiple levels. Translational control is one of the means by which TNF-alpha production is repressed in unstimulated cells. To examine the mechanism by which the translation of TNF-alpha mRNA transcripts is repressed, we have used an in vitro translation system. The AU-rich element (ARE) in the 3' UTR of TNF-alpha transcripts was sufficient to confer translational repression. This effect was observed using transcripts containing a 5' m(7)G cap but not uncapped transcripts, and was independent of a poly(A) tail. Sucrose gradient analysis revealed that ARE-containing transcripts were present at relatively lower amounts in 80S-associated fractions and higher amounts in non-ribosome-bound RNA fractions, with no accumulation of 48S-associated transcripts. ARE-mediated translational repression was competitively inhibited by ARE-containing transcripts. These data indicate that a TNF-alpha ARE-binding trans-acting factor(s) inhibits the association of the 43S complex with RNA transcripts.

MK2-induced tristetraprolin:14-3-3 complexes prevent stress granule association and ARE-mRNA decay.

Stress granules (SGs) are dynamic cytoplasmic foci at which stalled translation initiation complexes accumulate in cells subjected to environmental stress. SG-associated proteins such as TIA-1, TIAR and HuR bind to AU-rich element (ARE)-containing mRNAs and control their translation and stability. Here we show that tristetraprolin (TTP), an ARE-binding protein that destabilizes ARE-mRNAs, is recruited to SGs that are assembled in response to FCCP-induced energy deprivation, but not arsenite-induced oxidative stress. Exclusion of TTP from arsenite-induced SGs is a consequence of MAPKAP kinase-2 (MK2)-induced phosphorylation at serines 52 and 178, which promotes the assembly of TTP:14-3-3 complexes. 14-3-3 binding excludes TTP from SGs and inhibits TTP-dependent degradation of ARE-containing transcripts. In activated RAW 264.7 macrophages, endogenous TTP:14-3-3 complexes bind to ARE-RNA. Our data reveal the mechanism by which the p38-MAPK/MK2 kinase cascade inhibits TTP-mediated degradation of ARE-containing transcripts and thereby contributes to lipopolysaccharide-induced TNFalpha expression.

Geldanamycin inhibits the production of inflammatory cytokines in activated macrophages by reducing the stability and translation of cytokine transcripts.

OBJECTIVE: Heat-shock protein 90 (Hsp90) is critical in the intracellular signaling pathways that promote inflammatory cytokine production. Geldanamycin (GD) is a benzoquinone ansamycin that inhibits the function of Hsp90. GD inhibits the production of tumor necrosis factor alpha (TNFalpha) in activated macrophages and suppresses the progression of adjuvant-induced arthritis and experimental allergic encephalomyelitis in rodents. GD has been used to investigate the mechanisms by which Hsp90 regulates inflammatory cytokine production. METHODS: The macrophage cell line RAW264.7 (or primary peritoneal macrophages) was activated with lipopolysaccharide in the absence or presence of GD. The effect of GD on the transcription, stability, and translation of inflammatory cytokine messenger RNA (mRNA) was determined using nuclear run-on assays, mRNA decay assays, and sucrose gradient polysome profiles, respectively. RESULTS: Our data revealed that GD potently inhibits the production of TNFalpha, interleukin-6 (IL-6), and IL-1beta in activated macrophages. Although GD did not significantly reduce the transcription of inflammatory cytokine mRNA, it significantly decreased the stability of these transcripts. Polysome profiles indicated that GD also inhibited the translation of TNFalpha and IL-6 transcripts. These effects may be due, in part, to inhibition of p38 mitogen-activated protein kinase, a kinase known to regulate the stability and translation of inflammatory cytokine transcripts. CONCLUSION: These results indicate that the function of Hsp90 is important in the posttranscriptional control of inflammatory cytokine production.