Background: Increased morbidity in many patients with myasthenia gravis (MG) on long-term immunosuppression highlights the need for improved treatments. The aim of this study is to investigate the safety and efficacy of iscalimab (CFZ533), a fully human anti-CD40 monoclonal antibody, in patients with moderate-to-severe MG receiving standard-of-care (SoC) therapies.Methods: In this double-blind, placebo-controlled phase 2 study, symptomatic patients (n = 44) despite SoC were randomized 1:1 to receive intravenous iscalimab (10 mg/kg; n = 22) or placebo (n = 22) every 4 weeks for 6 doses in total. Patients were followed up for 6 months after the last dose. The total duration of the study was 52 weeks.Results: In total, 34 of 44 patients (77.3 %) completed the study. The primary endpoint, Quantitative MG score, did not change significantly between baseline and week 25 for iscalimab (median [90 % CI], -4.07 [-5.67, -2.47]) versus placebo (-2.93 [-4.53, -1.33]); however, non-thymectomized patients (n = 29) showed more favorable results (iscalimab, -4.35 [-6.07, -2.64] vs placebo, -2.26 [-4.16, -0.36]). A statistically significant difference between iscalimab and placebo groups was observed in MG Composite score (adjusted mean change: -4.19 [-6.67, -1.72]; p = 0.007) at week 13, and MG-Activities of Daily Living score (-1.93 [-3.24, -0.62]; p = 0.018) at week 21. Adverse events were comparable between the iscalimab (91 %) and placebo (96 %) groups.Conclusion: Iscalimab showed favorable safety and improvements compared with placebo in non-thymectomized patients with moderate-to-severe MG. It did not show any protective effect in patients with moderate-to-severe MG.

CFZ533 (iscalimab) is a nondepleting anti-CD40 antibody intended for inhibition of transplant organ rejection and treatment of autoimmune diseases. In a safety assessment in rhesus monkeys, CFZ533 was administered for 13 weeks up to 150 mg/kg/week subcutaneously. CFZ533 was shown previously to completely inhibit primary and secondary T-cell-dependent antibody responses. CD40 is expressed on B cells, antigen-presenting cells, and endothelial and epithelial cells, but is not expressed on T cells. Here, we demonstrate the complete suppression of germinal center formation in lymphoid organs. CFZ533 was well tolerated and did not cause any dose-limiting toxicity. However, the histological evaluation revealed increased numbers of CD4(+) and CD8(+) T cells in the T-cell-rich areas of lymph nodes enlarged in response to observed adenovirus and Cryptosporidium infections which suggest that T-cell immune function was unaffected. Background infections appear as the condition leading to unraveling the differential immunosuppressive effects by CFZ533. The presence of T cells at lymph nodes draining sites of infections corroborates the immunosuppressive mechanism, which is different from calcineurin-inhibiting drugs. Furthermore, CFZ533 did not show any hematological or microscopic evidence of thromboembolic events in rhesus monkeys, which were previously shown to respond with thromboembolism to treatment with anti-CD154 antibodies.

Background Primary Sjogren's syndrome is an autoimmune disease that presents as dryness of the mouth and eyes due to impairment of the exocrine glands. To our knowledge, no systemic therapies for primary Sjogren's syndrome have shown efficacy. CD40-CD154-mediated T cell-B cell interactions in primary Sjogren's syndrome contribute to aberrant lymphocyte activation in inflamed tissue, leading to sialadenitis and other tissue injury. Therefore, we investigated the safety and preliminary efficacy of iscalimab (CFZ533), a novel anti-CD40 monoclonal antibody, in patients with primary Sjogren's syndrome. Methods This multicentre, randomised, double-blind, placebo-controlled, proof-of-concept study took place at ten investigational sites across Europe (UK, n=4; Germany, Switzerland, and Hungary, n=1 each) and the USA (n=3). Eligible patients were aged 18-75 years and fulfilled the 2002 American European consensus group diagnostic dassification criteria for primary Sjogren's syndrome. In the double-blind phase of the trial, patients were randomly assigned (2:1) via computer-generated unique randomisation numbers to receive subcutaneous iscalimab (3 mg/kg) or placebo at weeks 0, 2, 4, and 8 (cohort 1) or intravenous iscalimab (10 mg/kg) or placebo at weeks 0, 2, 4, and 8 (cohort 2). Randomisation was stratified according to baseline intake of oral corticosteroids. At week 12, patients in both cohorts received open-label iscalimab (same dose and route) for 12 weeks. The primary objectives of the study were to assess the safety, tolerability, and efficacy of multiple doses of iscalimab in the two sequential dose cohorts. Safety and tolerability were assessed by adverse events and efficacy of iscalimab versus placebo was assessed by dinical disease activity, as measured by the change in European League Against Rheumatism Sjogren's syndrome disease activity index (ESSDAI) score after 12 weeks of treatment. Analyses were done on a per-protocol basis. The trial was registered with ClinicalTrials.gov, NCT02291029. Findings Between Oct 22, 2014, and June 28, 2016, we assessed 82 patients for eligibility (25 for cohort 1 and 57 for cohort 2). 38 patients were excluded because of ineligibility. In cohort 1, 12 patients were randomly assigned to receive either 3 mg/kg doses of iscalimab (n=8) or placebo (n=4), and in cohort 2, 32 patients were randomly assigned to receive either intravenous 10 mg/kg doses of iscalimab (n=21) or placebo (n=11). Adverse events were similar between iscalimab treatment groups and placebo groups, with adverse events occurring in all patients in cohort 1, and in 52% and 64% of the iscalimab and placebo groups, respectively, in cohort 2. Two serious adverse events were reported (one case of bacterial conjunctivitis in cohort 1 and one case of atrial fibrillation in cohort 2), which were unrelated to treatment with iscalimab. Intravenous treatment with iscalimab resulted in a mean reduction of 5.21 points (95% CI 0.96-9.46; one-sided p=0.0090) in ESSDAI score compared with placebo. There was no signficiant difference in ESSDAI score between subcutaneous iscalimab and placebo. Interpretation To our knowledge, this is the first randomised, placebo-controlled proof-of-concept study of a new investigational drug for primary Sjogren's syndrome that indicates preliminary efficacy. Our data suggest a role of CD40-CD154 interactions in primary Sjogren's syndrome pathology and the therapeutic potential for CD40 blockade in this disease should be investigated further. Copyright (C) 2020 Elsevier Ltd. All rights reserved.

Introduction: Development of calcineurin inhibitor (CNI)-sparing regimens that can provide long-term renal and other benefits while preserving anti-rejection efficacy remains a key unmet medical need in liver transplantation (LT). CFZ533 (iscalimab), a fully human anti-CD40 monoclonal antibody, has been shown to prolong allograft survival in preclinical models and block T cell-dependent antibody responses in humans. Here, the rationale and design of the CONTRAIL I study are presented. This Phase 2 study aims to evaluate the efficacy, safety, pharmacokinetics (PK) and pharmacodynamics (PD) of high and low doses of iscalimab versus standard tacrolimus (TAC) regimen in de novo liver transplant recipients (LTRs). Materials and Methods: CONTRAIL I (NCT03781414) is a 12-month, multicenter, open-label study with a 12 month follow-up period. De novo LTRs aged 18–70 years receiving grafts from deceased donors with an estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m2 will be randomized (2:3:3) on Day 8±1 post-LT to standard TAC, low-dose iscalimab, or high-dose iscalimab (Figure). All patients will receive mycophenolate mofetil throughout the study and steroids for the first 4 months following LT. The primary objective is to evaluate the rate of composite efficacy failure (biopsy-proven acute rejection (rejection activity index ≥3], graft loss, or death) at 12 months. Key secondary objectives will include efficacy event rates, renal function (evolution of eGFR), safety and tolerability, PK, and PD (soluble CD40 in plasma) of iscalimab over 12 and 24 months. Key exploratory objective is to evaluate differences in liver histopathology with high and low doses of iscalimab versus a standard TAC regimen (using Banff, rejection activity index, modified hepatic activity index, and liver fibrosis score) at 12 months post-transplantation. Results and Discussion: At least 128 LTRs will be randomized from multiple centers in Europe and North America. The first patient first visit was achieved on October 2019; currently the study is recruiting patients, and study completion is expected by Q4 2022. Conclusion: The study findings will identify the iscalimab dose for further clinical development and inform the safety and efficacy of iscalimab as a CNI-free regimen in de novo LTRs.

Iscalimab is a fully human, CD40 pathway blocking, nondepleting monoclonal antibody being developed as an immunosuppressive agent. We describe a first-in-human, randomized, double-blind, placebo-controlled study investigating the safety, tolerability, pharmacokinetics, and pharmacodynamics of iscalimab in healthy subjects and rheumatoid arthritis patients. Healthy subjects (n = 56) received single doses of intravenous iscalimab (0.03, 0.1, 0.3, 1, or 3 mg/kg), or subcutaneous iscalimab (3 mg/kg), or placebo. Rheumatoid arthritis patients (n = 20) received single doses of intravenous iscalimab (10 or 30 mg/kg) or placebo. Iscalimab exhibited target-mediated drug disposition resulting in dose-dependent and nonlinear pharmacokinetics. Complete (≥90%) CD40 receptor occupancy on whole blood B cells was observed at plasma concentrations >0.3-0.4 µg/mL. In subjects receiving 3 mg/kg iscalimab, antibody responses to keyhole limpet hemocyanin were transiently suppressed. CD40 occupancy by iscalimab prevented ex vivo human rCD154-induced expression of CD69 on B cells in whole blood. All doses were generally safe and well tolerated, with no clinically relevant changes in any safety parameters, including no evidence of thromboembolic events. Iscalimab appears to be a promising blocker of the CD40-CD154 costimulatory pathway with potential use in transplantation and other autoimmune diseases.

Background: Primary Sjögren’s syndrome (pSS) is a systemic progressive autoimmune disease characterised by formation of lymphoid structures and germinal centres within glandular tissue. Iscalimab (CFZ533) is a novel monoclonal antibody that potently and selectively blocks CD40, a co-stimulatory pathway receptor important for germinal centre reactions and B cell activation. Iscalimab showed clinical efficacy in a Proof of Concept randomised controlled trial at a dose of 10 mg/kg intravenously (IV), whereas subcutaneous (SC) dosing at 3 mg/kg was associated with unexpectedly low plasma concentrations and reduced efficacy, likely due to efficient pre-systemic target-mediated clearance. Objectives: To test IV versus SC loading doses of iscalimab followed by SC maintenance dosing, as a means of achieving target drug exposure and clinical efficacy. Methods: Patients with clinically active pSS [EULAR Sjögren’s Syndrome Disease Activity Index (ESSDAI) ≥6] were randomised to receive either 600 mg SC iscalimab weekly on 4 occasions, followed by 300 mg SC weekly until week 12, or a single IV dose of 10 mg/kg iscalimab on study Day 1, followed by 300 mg SC weekly until week 12. Subjects and investigator staff remained blinded to study treatment allocation until first dosing. Results: Twenty-five patients were randomised; 13 in the SC loading and 12 in the IV loading arms. Baseline characteristics were similar to the previous phase IIa cohorts with mean ESSDAI scores of 12.7 (SD 6.1) and 10.4 (5.9) in the SC and IV loading arms respectively. In Arm 1 (SC) and Arm 2 (IV), the mean trough plasma concentrations were 169 μg/mL (SD 64.1, CV 38%) and 135 μg/mL (SD 70.9, CV 53%) on Day 85, respectively. Both values were well above levels previously reported to be sufficient for suppression of germinal centre development and T dependent antigen responses in cynomolgus monkeys. Consistent with this finding, clinically important improvements were seen in both arms with a mean decrease in ESSDAI scores of -5.5 (+/- SD: 5.5) and -7.6 (+/- 7.1) points from baseline to Day 85 in the SC and IV dosing arms. Improvements were also seen in EULAR Sjögren’s Syndrome Patient Reported Index (ESSPRI) scores: -1.67 (+/- 1.8) and -1.17 (+/- 2.3), respectively. Other secondary efficacy outcomes showed similar patterns of improvement. Treatment with iscalimab was associated with a reduction in the germinal centre-related serum biomarker CXCL13 in both groups. Overall, iscalimab was safe and well-tolerated with no new safety signal emerging. One subject experienced three SAEs (hemarthrosis, worsening of right knee pain and swelling requiring arthroscopy) in the safety follow-up period, all unrelated to study drug. Conclusion: These results further support the safety and efficacy of iscalimab in pSS and the suitability of SC dosing for future development. Disclosure of Interests: Benjamin Fisher Consultant for: Novartis, Roche, MedImmune, Bristol-Myers Squibb, Antónia Szántó: None declared, Wan Fai Ng: None declared, Michele Bombardieri Grant/research support from: Celgene, Consultant for: Medimmune, Maximilian Posch: None declared, Athena Papas Grant/research support from: Novartis, Consultant for: Novartis, Arwa Farag: None declared, Thomas Daikeler: None declared, Bettina Bannert: None declared, Alan Kivitz Shareholder of: Novartis, Consultant for: Abbvie, Janssen, Pfizer, UCB, Genzyme, Sanofi, Regeneron, Boehringer Ingelheim, Sun Pharma Advanced Research, Flexion., Paid instructor for: Celgene, Horizon, Merck, Novartis, Pfizer, Genzyme, Sanofi, Regeneron, Speakers bureau: Celgene, Horizon, Merck and Genetech, Flexion, Steven Carsons Grant/research support from: Novartis, David Isenberg: None declared, Francesca Barone Grant/research support from: GlaxoSmithKline, Roche, UCB Pharma, Actelion, ONO Pharmaceutical, Consultant for: GlaxoSmithKline, Roche, Actelion, ONO Pharmaceutical, Simon J. Bowman Grant/research support from: Previously UCB Pharma (to University of Birmingham) and Roche, Consultant for: 2016-7: Novartis, Mitsubishi Tanabe Pharma 2017-8: AstraZeneca, MedImmune, GFK, Xtlbio, ONO Pharmaceutical 2018-9: Novartis, AstraZeneca, UCB Pharma, Pascal Espie Employee of: Novartis, Grazyna Wieczorek Employee of: Novartis, Pierre Moulin Employee of: Novartis, David Floch Employee of: Novartis, Cyrielle Dupuy Employee of: Novartis, Amanda Nguyen Employee of: Novartis, Andrew Wright Shareholder of: Novartis, Employee of: Novartis, Michael Rotte Employee of: Novartis, James Rush Employee of: Novartis, Peter Gergely Employee of: Novartis

Context: The CD40-CD154 co-stimulatory pathway plays an important role in the pathogenesis of Graves disease (GD) by promoting autoreactive B-cell activation. Objective: Evaluate efficacy and safety of a human, blocking, nondepleting anti-CD40 monoclonal antibody, iscalimab, in hyperthyroid patients with GD. Design: Open-label, phase II proof-of-concept study. Setting: Multicenter. Patients: Fifteen with GD. Intervention: Patients received 5 doses of iscalimab at 10 mg/kg intravenously over 12 weeks. Main outcome measures: Thyroid-related hormones and autoantibodies, plasma soluble CD40, free CD40 on B cells, soluble CXCL13, pharmacokinetics, and safety were assessed. Results: The iscalimab intervention resulted in complete CD40 engagement for up to 20 weeks. A clinical response and biochemical euthyroidism was observed in 7 of 15 (47%) patients. Free and total triiodothyronine and thyroxine normalized in 7 patients who did not receive any rescue medication with antithyroid drugs (ATD), and 2/15 (13.3%) showed normal thyrotropin. Six (40%) patients required ATD. Four of 7 responders relapsed after treatment completion. Serum concentrations of thyrotropin receptor autoantibodies (TSH-R-Ab) significantly declined in all patients (mean 15.3 IU/L vs 4.0 IU/L, 66% reduction; P < 0.001) and TSH-R-Ab levels normalized in 4 (27%). Thyroperoxidase and thyroglobulin autoantibodies significantly decreased in responders. Iscalimab rapidly reduced serum CXCL13 concentrations (P < 0.001). Twelve (80.0%) patients reported at least 1 adverse event (AE). All treatment-related AE were mild or moderate and resolved by end of the study. Conclusion: Iscalimab was generally safe and clinically effective in a subgroup of hyperthyroid GD patients. The potential therapeutic benefit of iscalimab should be further tested.

Objective: Graves’ disease (GD) is an autoimmune disorder characterized by thyrotropin receptor autoantibody (TSHR-Ab)-mediated pathology, leading to hyperthyroidism. To date there is no pharmacotherapy that addresses the underlying pathogenesis. The CD40-CD154 (CD40L) co-stimulatory pathway plays an important role in the pathogenesis of GD by promoting auto-reactive B cell activation and intrathyroidal ectopic lymphoid structure formation and function. Iscalimab (CFZ533) is a fully human, blocking and non-depleting anti-CD40 monoclonal antibody. The purpose of this study was to investigate the efficacy and safety of Iscalimab in patients with Graves’ hyperthyroidism. Methods: In total, fifteen patients with Graves’ hyperthyroidism were enrolled in an open label Phase I proof-of concept study and all completed the trial. Each patient received five doses of Iscalimab at 10 mg/kg IV over 12 weeks. We assessed the effects of Iscalimab on thyroid-related hormones (baseline TSH, free and total T3/T4) and autoantibodies (TSHR-Ab) over 36 weeks following the first dose of Iscalimab. Safety, pharmacokinetics, soluble CD40 levels in plasma, free CD40 on whole blood CD19-positive B cells, and CXCL13 were also assessed. Results: Based on the CD40 occupancy and plasma levels of soluble CD40, the intervention resulted in full CD40 engagement for up to 20 weeks (12-week treatment + 8 week follow up). A clinical response and biochemical euthyroidism was observed in seven out of 15 (46.7%) by Day 211. Free T3/T4 normalized in seven (46.7%) patients who did not received any rescue medication with anti-thyroid drugs. Two further patients (13.3%) did not normalize but did not require rescue medication. In contrast, six (40%) patients required rescue medication with anti-thyroid drugs by Day 141. No patients achieved normalization of TSH by Day 85, however, two out of 15 patients (13.3%) showed normal TSH by Day 169. The levels of free thyroid hormones and TSHR-Ab levels declined over time up to Day 211. The mean levels of TSHR-Ab declined from 15.3 IU/L (baseline) to 9.4 IU/L at Day 85 (35% reduction, P<0.001), then further decreased to 4.0 IU/L at day 141 (66% reduction, P<0.001). The TSHR-Ab levels fell in normal range in four out of 15 patients (26.7%). Treatment with Iscalimab was associated with a rapid and significant reduction in the serum levels of CXCL13 (94.1 pg/mL at baseline to 68.5 pg/mL at Day 15) and remained at similar levels during the 12 week treatment period. Twelve patients reported at least one adverse event. Most events were mild in nature (34 in 8 patients, 53.3%) and few were moderate (5 in 4 patients, 26.7%). Conclusions: Iscalimab was generally safe and clinically effective in a subgroup of patients with Graves’ hyperthyroidism. These encouraging results suggest that Iscalimab may be an attractive strategy as the immunomodulation treatment for GD.

s Committee: Chair: Kentaro Ikeda, DDS, MPH Co-Chair: Bhavik Desai, DMD, PhD #11 – 3:00-3:10pm The Parotid Gland in Primary Sjögren’s Syndrome: Association of Ultrasound, Histopathology and Saliva Production in the Diagnostic Work-up *Konstantina Delli, Esther Mossel, Erlin Haacke, Bert van der Vegt, Suzanne Arends, Uzma Nakshbandi, Jolien F van Nimwegen, Alja J Stel, Fred KL Spijkervet, Frans GM Kroese, Arjan Vissink, Hendrika Bootsma University Medical Center Groningen, Netherlands Objectives: The parotid glands are commonly involved in primary Sjögren’s syndrome (pSS). The aim of this study was to assess the diagnostic accuracy of ultrasound of the parotid glands (PSGUS) compared with the parotid histopathology and parotid saliva production. Methods: We included consecutive patients suspected with pSS. All patients underwent a full diagnostic work-up according to ACR-EULAR criteria, including PSGUS, parotid gland biopsy and collection of stimulated parotid saliva. For PSGUS, the average score of hypoechogenic areas in both parotid glands was applied (range 0-3). On H&E stained sections from parotid gland biopsies, focus score, presence of lymphoepithelial lesions (LELs) and germinal centers (GCs) were assessed. The area of lymphocytic infiltrate was calculated digitally on CD45 stained sections. The relative increase of IgG expressing plasma cells (≥30%) was evaluated on sections stained for IgA and IgG. PSGUS score was associated with focus score, percentage of infiltrate and saliva flow and compared with plasma cell shift, LELs and GCs by calculating the percentage of absolute agreement, sensitivity and specificity. Results: In total, of the 111 included patients, 53 fulfilled the ACR-EULAR classification criteria for pSS. PSGUS score showed moderate correlation with focus score (ρ=0.494, p<0.001) and percentage of lymphocytic infiltrate (ρ=0.575, p<0.001). There was a moderate to good absolute agreement between PSGUS and focus score (78.5%), plasma cell shift (79.8%), LELs (81.4%) and GCs (82.7%). ‘Presence of hypoechogenic areas’ was not very sensitive to predict focus score (69.2%), plasma cell shift (45.8%), LELs (61.5%) or GCs (34.6%). Interestingly, almost all patients with <25% presence of hypoechogenic areas in glandular parenchyma were also negative for GCs (98.7%). A substantial amount of these patients did not have a positive focus score (81.4%), plasma cell shift (90.7%) or LELs (87.8%). There was a fair reversed correlation between PSGUS and stimulated parotid saliva flow (ρ=-0.259, p=0.07). Conclusions: This is the first study comparing the diagnostic accuracy of PSGUS with histopathology and salivary secretion in detail. PSGUS and histopathology are stronger associated than PSGUS and parotid secretion. Specificity of PSGUS increases when results are compared to plasma cell shift, LELs and GCs, instead of focus score. #12 – 3:10-3:20pm Novel Anti-CD40 Monoclonal Antibody CFZ533 in Patients with Primary Sjogren Syndrome: A Phase IIa Double-Blind, Placebo–Controlled Randomized Trial *Arwa Farag, Athena Papas, Benjamin Fisher, Margit Zeher, Wan-Fai Ng, Michele Bombardieri, Maximilian Posch, Thomas Daikeler, Bettina Bannert, Alan Kivitz, Steven Carsons, David Isenberg, Francesca Barone, Simon Bowman, Pascal Espie, Grazyna Wieczorek, Pierre Moulin, David Floch, Cyrielle Dupuy, Xiaohui Ren, Petra Faerber, Andrew Wright, Hans Ulrich Hockey, Michael Rotte, James Rush, Peter Gergely Tufts University School of Dental Medicine, USA

The CD40-CD154 costimulatory pathway is essential for T cell-dependent immune responses, development of humoral memory, and antigen presenting cell function. These immune functions have been implicated in the pathology of multiple autoimmune diseases as well as allograft rejection. We have generated CFZ533, a fully human, pathway blocking anti-CD40 monoclonal antibody that has been modified with a N297A mutation to render it unable to mediate Fcγ-dependent effector functions. CFZ533 inhibited CD154-induced activation of human leukocytes in vitro, but failed to induce human leukocyte activation. Additionally, CFZ533 was unable to mediate depletion of human CD40 expressing B cells. In vivo, CFZ533 blocked primary and recall T cell-dependent antibody responses in nonhuman primates and abrogated germinal formation without depleting peripheral blood B cells. We also established a relationship between plasma concentrations of CFZ533 and CD40 pathway-relevant pharmacodynamic effects in tissue. Collectively these data support the scientific rationale and posology for clinical utility of this antibody in select autoimmune diseases and solid organ transplantation.

Objectives: Primary Sjogren syndrome (pSS) is a progressive autoimmune disease characterized by formation of ectopic germinal centers in exocrine glands and secretory gland dysfunction with subset of patients developing extraglandular manifestations. CFZ533 is a novel monoclonal antibody that selectively blocks CD40, a co-stimulatory pathway receptor essential for germinal center reactions and other immune-mediated functions implicated in pSS pathogenesis. We conducted a randomized, double-blind, placebo-controlled, multicentric, partial crossover, Phase IIa Proof of Concept (PoC) study to evaluate the safety, tolerability and efficacy of CFZ533 in patients with pSS.

CFZ533 is a pathway blocking, nondepleting anti-CD40 antibody that is in clinical development for inhibition of transplant organ rejection and therapy for autoimmune diseases. A 26-week GLP toxicity study in sexually mature Cynomolgus monkeys was conducted in order to support chronic application of CFZ533. CFZ533 was subcutaneously administered at doses up to 150 mg/kg/week and was safe and generally well tolerated. CFZ533 showed no adverse effects for cardiovascular, respiratory, and neurobehavioral endpoints, and no changes were observed for blood lymphocyte and platelet counts or blood coagulation markers. In line with the nondepleting nature of CFZ533, CD20+ B cells in the blood were only marginally reduced. A complete suppression of germinal center (GC) development in lymph nodes and spleen was the most prominent result of post-mortem histological investigations. This was corroborated by an abrogated T-dependent antibody response (TDAR) to the antigen Keyhole Limpet Hemocyanin (KLH) as well as an absence of anti-drug antibodies (ADAs) in the absence of B cell depletion as seen with immunophenotyping and histology. When serum levels of CFZ533 in recovery animals dropped levels necessary for full CD40 occupancy on B cells, all animals were able to mount a TDAR to KLH. All histological changes also reverted to normal appearance after recovery. In summary, CFZ533 was shown to be well tolerated and safe in the 26-week toxicity study with a distinct pharmacodynamic profile in histology and immune function.

CFZ533 is a pathway blocking, non-depleting anti-CD40 antibody that is in clinical development for inhibition of transplant organ rejection and therapy for autoimmune diseases. A 26-week GLP toxicity study in sexually mature Cynomolgus monkeys was conducted in order to support chronic application of CFZ533. CFZ533 was subcutaneously administered at doses up to 150 mg/kg/week and was safe and generally well tolerated . CFZ533 showed no adverse effects for cardiovascular, respiratory and neurobehavioral endpoints, and no changes were observed for blood lymphocyte and platelet counts or blood coagulation markers. In line with the non-depleting nature of CFZ533, CD20+ B cells in the blood were only marginally reduced. A complete suppression of germinal center (GC) development in lymph nodes and spleen was the most prominent result of post-mortem histological investigations. This was corroborated by an abrogated T dependent antibody response (TDAR) to the antigen Keyhole Limpet Hemocyanin (KLH) in the absence of B cell depletion as seen with immunophenotyping and histology. When serum levels of CFZ533 in recovery animals dropped below the level necessary for full CD40 occupancy on B cells, all animals were able to mount primary TDAR to KLH. All histological changes also reverted to normal appearance after recovery. In summary, CFZ533 was shown to be well tolerated and safe in the 26-week toxicity study with a distinct pharmacodynamic profile in histology and immune function.

Background Aberrant CD40-CD154 pathway signaling has been linked to pathology in autoimmune disease. Blocking the CD40-CD154 pathway prevents T cell-dependent antibody responses, germinal center formation and prolongs renal allograft survival in non-human primates. CFZ533 is a novel, fully human, non-agonistic Fc-silent, anti-CD40 monoclonal antibody being developed for treatment of autoimmune diseases and prevention of rejection in solid-organ transplantation. Objectives To assess the safety, pharmacokinetics (PK) and pharmacodynamics activity (PD) of CFZ533 in humans. Methods A double-blind, placebo controlled, ascending, single-dose study was conducted in 48 healthy volunteers (HV) receiving 0.03, 0.1, 0.3, 1.0, 3.0 mg/kg i.v., 3.0 mg/kg s.c. CFZ533 or matching placebo (3:1) as well as in 12 rheumatoid arthritis (RA) patients receiving 10.0 mg/kg i.v. CFZ533 or placebo (1:1). HVs were immunized with a single intramuscular dose of a T-cell dependent neo-antigen, Keyhole Limpet Hemocyanin (KLH) with alum adjuvant on Day 3 and again between Day 29–85 depending on predicted loss of CD40 receptor occupancy (RO) as a function of CFZ533 dose. Blood samples for PK, CD40 RO and anti-KLH IgG and IgM profiling were collected at multiple time points during the study. Anti-KLH antibodies were assessed using a validated human ELISA system with an LOQ of 0.7 (IgG) and 2.1 (IgM) μg/mL. RA patients were evaluated for safety, PK and RO. Results All doses of CFZ533 and KLH were safe and well tolerated. CFZ533 PK concentrations were quantifiable at all dose levels tested. Complete (≥90%) peripheral CD40 RO by 3 mg/kg i.v. CFZ533 in HVs was maintained for 28 days. During this period of full RO, full suppression of the primary humoral response to KLH was evident in all treated subjects (KLH administered 2 days after CFZ533 dosing). After complete CFZ533 washout in 3 mg/kg cohort, all subjects mounted a robust anti-KLH response following a re-challenge on Day 85. Full RO in RA patients who received 10 mg/kg i.v. CFZ533 was maintained for at least 6 weeks and up to 10 weeks. Conclusions The favorable safety and tolerability profile of CFZ533 coupled with a predictable concentration-CD40 receptor occupancy relationship and suppression of a primary T cell-dependent antibody response supports future clinical trials of CFZ533 in select autoimmune diseases and transplantation. Disclosure of Interest A. Slade Employee of: Novartis Pharmaceuticals Corporation, East Hanover, NJ, USA, P. Koo Employee of: Novartis Pharmaceuticals Corporation, East Hanover, NJ, USA, Y. He Employee of: Novartis Pharmaceuticals Corporation, Cambridge, MA, USA, P. Espie Employee of: Novartis Pharmaceuticals Corporation, Basel, Switzerland, A. Auger-Sarrazin Employee of: Novartis Pharmaceuticals Corporation, Basel, Switzerland, J. Rush Employee of: Novartis Pharmaceuticals Corporation, Basel, Switzerland, P. Gergely Employee of: Novartis Pharmaceuticals Corporation, Basel, Switzerland

CD40-CD154 pathway blockade significantly prolongs allograft survival in non-human primates (NHPs). However, antibodies targeting CD154, while efficacious, were associated with an increased incidence of thromboembolic complications precluding clinical development. Current antibodies targeting CD40 effectively prolong renal allograft survival in NHPs without associated thromboembolic events but with accompanying B cell depletion, raising the question of whether CD40 blockade or B cell depletion was the effective mechanism. We developed a novel, Fc-silent (i.e. incapable of antibody-dependent cellular cytotoxicity or complement-dependent cytotoxicity) anti-human CD40 monoclonal antibody (OM11-62MF). OM11 blocked recombinant CD154-mediated activation of leukocytes in vitro and inhibited T cell-dependent antibody responses in vivo in the absence of significant peripheral B cell depletion. We tested OM11 and an Fc-competent anti-CD40 antibody in MHC-mismatched cynomolgus monkey renal allograft transplantation as monotherapies. Allograft survival was significantly prolonged in animals dosed with the Fc-competent anti-CD40 antibody (52, 22, 24 days) in comparison to untreated monkeys (survival ˜ 7 days; n = 9). Well-functioning renal allografts survived up to 100 days in OM11-treated animals (100, 100, 100, 98, 78 days) at which point the experiment was terminated and graft morphology examined by histology. In contrast to good graft morphology in OM11-dosed group, acute cellular rejection was observed in animals treated with Fc-competent anti-CD40. Rapid and complete peripheral B cell depletion was only observed with the Fc-competent antibody, despite full peripheral CD40 receptor occupancy by both antibodies throughout the duration of the experiment. OM11 was well-tolerated and we observed no evidence of thromboembolic events. Collectively, our results indicated that CD40 pathway blockade in the absence of B cell depletion inhibited T cell-dependent immune responses and prevented allograft rejection. Thus, use of the Fc-silent anti-CD40 antibody OM11 appears to be an attractive approach for preventing solid organ transplant rejection and treating autoimmune diseases involving T cell-dependent humoral immune mechanisms. DISCLOSURES:Rush, J.: Employee, Novartis Pharmaceuticals Corporation. Cordoba, F.: Employee, Novartis Pharmaceuticals Corporation. Wieczorek, G.: Employee, Novartis Pharmaceuticals Corporation. Audet, M.: Employee, Novartis Pharmaceuticals Corporation. Schneider, M.: Employee, Novartis Pharmaceuticals Corporation. Patel, D.: Employee, Novartis Pharmaceuticals Corporation. Heusser, C.: Other, Novartis Pharmaceuticals Corporation, Contractor. Bruns, C.: Employee, Novartis Pharmaceuticals Corporation. Ulrich, P.: Employee, Novartis Pharmaceuticals Corporation. Slade, A.: Employee, Novartis Pharmaceuticals Corporation. Klupp, J.: Employee, Novartis Pharmaceuticals Corporation.