Complement Inhibition Alleviates Cholestatic Liver Injury Through Mediating Macrophage Infiltration and Function in Mice

Background and AimsCholestatic liver injury (CLI), which is associated with inflammatory reactions and oxidative stress, is a serious risk factor for postoperative complications. Complement system is involved in a wide range of liver disorders, including cholestasis. The present study assessed the role of complement in CLI and the therapeutic effect of the site-targeted complement inhibitor CR2-Crry in CLI.MethodsWild-type and complement gene deficient mice underwent common bile duct ligation (BDL) to induce CLI or a sham operation, followed by treatment with CR2-Crry or GdCl3. The roles of complement in CLI and the potential therapeutic effects of CR2-Crry were investigated by biochemical analysis, flow cytometry, immunohistochemistry, ELISA, and quantitative RT-PCR.ResultsC3 deficiency and CR2-Crry significantly reduced liver injuries in mice with CLI, and also markedly decreasing the numbers of neutrophils and macrophages in the liver. C3 deficiency and CR2-Crry also significantly reduced neutrophil expression of Mac-1 and liver expression of VCAM-1. More importantly, C3 deficiency and CR2-Crry significantly inhibited M1 macrophage polarization in these mice. Intravenous injection of GdCl3 inhibited macrophage infiltration and activation in the liver. However, the liver injury increased significantly. BDL significantly increased the level of lipopolysaccharide (LPS) in portal blood, but not in peripheral blood. GdCl3 significantly increased LPS in peripheral blood, suggesting that macrophages clear portal blood LPS. Oral administration of ampicillin to in GdCl3 treated mice reduced LPS levels in portal blood and alleviated liver damage. In contrast, intraperitoneal injection LPS increased portal blood LPS and reversed the protective effect of ampicillin. Interestingly, C3 deficiency did not affect the clearance of LPS.ConclusionsComplement is involved in CLI, perhaps mediating the infiltration and activation of neutrophils and macrophage M1 polarization in the liver. C3 deficiency and CR2-Crry significantly alleviated CLI. Inhibition of complement could preserve the protective function of macrophages in clearing LPS, suggesting that complement inhibition could be useful in treating CLI.

Characterization of Novel P-Selectin Targeted Complement Inhibitors in Murine Models of Hindlimb Injury and Transplantation

The complement system has long been recognized as a potential druggable target for a variety of inflammatory conditions. Very few complement inhibitors have been approved for clinical use, but a great number are in clinical development, nearly all of which systemically inhibit complement. There are benefits of targeting complement inhibition to sites of activation/disease in terms of efficacy and safety, and here we describe P-selectin targeted complement inhibitors, with and without a dual function of directly blocking P-selectin-mediated cell-adhesion. The constructs are characterized in vitro and in murine models of hindlimb ischemia/reperfusion injury and hindlimb transplantation. Both constructs specifically targeted to reperfused hindlimb and provided protection in the hindlimb ischemia/reperfusion injury model. The P-selectin blocking construct was the more efficacious, which correlated with less myeloid cell infiltration, but with similarly reduced levels of complement deposition. The blocking construct also improved tissue perfusion and, unlike the nonblocking construct, inhibited coagulation, raising the possibility of differential application of each construct, such as in thrombotic vs. hemorrhagic conditions. Similar outcomes were obtained with the blocking construct following vascularized composite graft transplantation, and treatment also significantly increased graft survival. This is outcome may be particularly pertinent in the context of vascularized composite allograft transplantation, since reduced ischemia reperfusion injury is linked to a less rigorous alloimmune response that may translate to the requirement of a less aggressive immunosuppressive regime for this normally nonlife-threatening procedure. In summary, we describe a new generation of targeted complement inhibitor with multi-functionality that includes targeting to vascular injury, P-selectin blockade, complement inhibition and anti-thrombotic activity. The constructs described also bound to both mouse and human P-selectin which may facilitate potential translation.

Complement Inhibition Reduces Post-Hemorrhagic Hydrocephalus in Mouse Neonatal Germinal Matrix Hemorrhage

IntroductionGerminal matrix hemorrhage (GMH) is a devastating disease of infancy that results in intraventricular hemorrhage, post-hemorrhagic hydrocephalus (PHH), periventricular leukomalacia and neurocognitive deficits. There are no curative treatments and limited surgical options. We developed a novel mouse model of GMH and investigated the role of complement in PHH development.MethodsWe utilized a neonatal mouse model of GMH involving injection of collagenase into the subventricular zone of post-natal day four (P4) pups. Animals were randomized into four experimental arms: Naïve, sham injured, injured and vehicle (PBS) treated, and injured and CR2Crry-treated (a pan-complement inhibitor). Histopathologic and immunofluorescence analyses were performed at P14 with a focus on parameters of neuroinflammation and neuroprotection. Survival was monitored through day 45, prior to which cognitive and motor function was analyzed.ResultsThe complement inhibitor CR2Crry, which binds C3 complement activation products, localized specifically in the brain following systemic administration after GMH. Compared to vehicle treatment, CR2Crry treatment reduced PHH and lesion size, which was accompanied by decreased perilesional complement deposition, decreased astrocytosis and microgliosis, and the preservation of dendritic and neuronal density. Progression to PHH and neuronal loss was linked to microglial phagocytosis of complement opsonized neurons, which was reversed with CR2Crry treatment. Complement inhibition also improved survival and weight gain, and improved motor performance and cognitive outcomes measured in adolescent GMH mice. ConclusionComplement plays an important role in the pathological sequelae of GMH. Complement inhibition represents a novel therapeutic approach to reduce disease progression in neonatal GMH and PHH, for which there is currently no treatment outside of surgical intervention.

Interim Analysis of an Open-Label, Ascending-Dose, Phase 1 Study of the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single Doses of the Subcutaneously Administered Human Monoclonal Antibody Pozelimab in Combination with Single Doses of the Subcutaneously Administered siRNA Cemdisiran in Healthy Volunteers

Introduction. Pozelimab (REGN3918) and cemdisiran (ALN-CC5) are C5 inhibitors under development for the treatment of paroxysmal nocturnal hemoglobinuria (PNH), myasthenia gravis (MG), and other diseases in which tissue damage is mediated by terminal complement pathway activity. Pozelimab is a fully human monoclonal immunoglobulin G4P (IgG4P) antibody directed against C5, and cemdisiran is a synthetic small interfering RNA (siRNA) targeting C5 mRNA. Both agents can be administered via subcutaneous (SC) injection. Pharmacokinetic (PK)/pharmacodynamic (PD) modeling based on observed data from both pozelimab and cemdisiran healthy volunteer studies (NCT03115996, NCT02352493) suggests that, by combining cemdisiran and pozelimab, the dose of both agents may be significantly reduced and the interval for SC dosing of pozelimab may be significantly increased. Objectives. To provide initial safety and tolerability data for a SC cemdisiran/pozelimab combination approach. Methods. This is an ongoing phase 1, open-label, parallel-dose cohort combination study (NCT04601844) assessing the safety and tolerability of ascending doses of SC pozelimab in combination with SC cemdisiran when administered on the same day or sequentially, on different days, in healthy subjects. Cohort Descriptions. Three parallel ascending-dose cohorts, consisting of six subjects each, were selected based on PK/PD modeling using observed data from both pozelimab and cemdisiran non-combination healthy volunteer studies: Cohort 1: Cemdisiran low dose SC followed by pozelimab low dose SC, administered on different days Cohort 2: Cemdisiran high dose SC followed by pozelimab low dose SC, administered on different days Cohort 3: Cemdisiran high dose SC and pozelimab high dose SC, both administered on the same day Dose regimens were designed to limit the duration of >50% complement inhibition for no longer than 8 weeks, to mitigate risk in the enrolled healthy subjects. An optional additional Cohort 4 was included in the study design and this interim analysis was planned to review safety data to guide the decision regarding whether to enroll this cohort and to inform its dose selection. Interim Analysis: An interim safety analysis was performed with a data cut-off corresponding to study day 127 for Cohort 1, study day 85 for Cohort 2, and study day 71 for Cohort 3. Eighteen healthy volunteer subjects, nine female and nine male, with a mean age of 36 years (standard deviation 9.5 years), were randomized to one of the three cohorts. Demographic and baseline characteristics were comparable for subjects in each cohort. A total of 47 treatment emergent adverse events (TEAEs) were reported, with comparable distribution across cohorts, all mild to moderate in severity with no severe TEAEs. "Nervous system disorders" was the TEAE System Organ Class with the most subjects for all three cohorts, occurring in 12 (66.7%) of the 18 subjects. "Headache" was the most frequent MedDRA Preferred Term for all three cohorts, occurring in 11 (61.1%) of the 18 subjects. All TEAEs were recovered or recovering at the time of data cut-off, and there were no study drug discontinuations or interruptions of treatment due to TEAEs. There were no serious TEAEs or deaths. There were no clinically meaningful findings or treatment-emergent changes reported on the vital signs or laboratory safety tests. Conclusions: The combined SC administration of pozelimab and cemdisiran represents a promising approach to achieve therapeutically significant complement inhibition for extended durations. An interim safety analysis demonstrated that the combined administration was generally safe and well tolerated. Final PK/PD analysis from this healthy volunteer study will allow for assessment of agreement between modeling predictions and observed data, and further inform combination dose regimens for studies in target patient populations. Disclosures van Zyl: Regeneron Pharmaceuticals, Inc.: Current Employment. Weyne: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Chaudhari: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Harari: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Levy: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Miller: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Chen: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Meagher: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Rodgers: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Perlee: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Morton: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Weinreich: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company. Yancopoulos: Regeneron Pharmaceuticals, Inc.: Current Employment, Current holder of stock options in a privately-held company.

Sars-Cov-2 Vaccination in Patients with Paroxysmal Nocturnal Hemoglobinuria: An Italian Multicenter Survey

SARS-CoV-2 infection and vaccination have raised concerns in paroxysmal nocturnal hemoglobinuria (PNH). In fact, PNH patients carry an increased infectious risk secondary to complement inhibition treatment or associated bone marrow failure (BMF), and may therefore benefit from preventive strategies such as vaccinations. On the contrary, vaccines can be numbered among inflammatory complement amplifiers (e.g., infections, traumas, surgery), potentially triggering a disease exacerbation. In PNH patients on complement inhibitors, this phenomenon has been defined pharmacodynamic breakthrough hemolysis (BTH). Based on isolated reports of BTH following SARS-CoV-2 vaccines, we conducted a survey among 5 Italian reference centers to evaluate complications and BTH occurrence in PNH patients who completed the SARS-CoV-2 vaccination schedule from January, 2 2021 until the time of writing. Adverse events, hematologic and hemolytic parameters were recorded within 7-10 days before and after each dose of vaccine. A total of 67 patients (females/males 43/24, median age 47.6 years, range 21-90.5) were eligible for the analysis. According to the International PNH Interest Group classification, 45 patients suffered from hemolytic PNH, 20 from PNH in the context of BMF syndromes (aplastic anemia or myelodysplastic syndrome), and 2 from subclinical PNH. Fifty-five subjects (82%) were on regular complement inhibition therapy, i.e., eculizumab (N=35), ravulizumab (N=13), subcutaneous anti-C5 (N=3), anti-factor B (N=2) and ravulizumab + anti-factor D combination (N=2). Vaccines (Comirnaty/Pfizer-BioNTech N=53, mRNA-1273/Moderna N=12, and ChAdOx1 nCov-19/AstraZeneca N=2) were complessively well-tolerated, with 3 non-hematologic adverse events after the first dose (2 fever and 1 exercise-induced tachycardia, grade 1 according to CTCAE v5.0) and 2 after the second one (fever, accompanied by vomit in one patient, grade 1). During the observation period, 3 BTH and 1 hemolytic exacerbation were recorded (5.9% of patients), as detailed in Table 1. The most severe episode occurred in a young woman (Patient 3) on subcutaneous ravulizumab who experienced a hemoglobin (Hb) drop >2 g/dL, marked clinical signs of intravascular hemolysis and lactate dehydrogenase (LDH) increase >1.5 x upper limit of normal (ULN) from baseline, which is considered a clinical BTH according to the criteria proposed by the Severe Aplastic Anemia Working Party of the European group for Bone Marrow Transplantation. The patient required hospitalization for additional treatment with recombinant erythropoietin and anti-thombotic/bacterial prophylaxis. The second more severe BTH was registered in a male patient (Patient 1) on oral anti-factor B who experienced a Hb drop >2 g/dL without an overt hemolytic flare, and required hospitalization for intravenous antibiotic therapy (concomitant urinary tract infection). The remaining two patients experienced a subclinical BTH (Patient 2) and a hemolytic flare (Patient 4, not on complement inhibition). On the whole, a median delta variation from usual values of Hb and LDH of -25% (range -26+3%) and +80% (+18+105%) were observed, respectively. Of note, 3 episodes occurred after the second dose of vaccine, generally within 24-48 hours. Anti-complement drugs were not modified/discontinued in any of the 3 patients on regular treatment. Patients not experiencing BTH (94.1%) showed stable hematologic parameters after the first dose (Hb/LDH median delta variations from baseline -1%/+1%, range -14+12%/-32+40%) and the second dose of vaccine (Hb/LDH median delta variations from baseline +1%/0%, range -18+47%/-76+41%). Of note, 4 patients with a previous SARS-CoV-2 infection completed the vaccination without any complication/PNH exacerbation. In conclusion, this survey shows that BTH/hemolytic flares following SARS-CoV-2 vaccines are observed in about 6% of PNH patients, may be clinically relevant but manageable, and should not discourage vaccination. BTH has been registered mostly few days after the second dose of vaccine, suggesting a "booster" effect favoring a higher inflammatory response. Watchful clinical and laboratory monitoring is advised, in order to promptly recognize severe hemolytic flares in both treated and naïve patients. Figure 1 Figure 1. Disclosures Fattizzo: Novartis: Speakers Bureau; Kira: Speakers Bureau; Alexion: Speakers Bureau; Annexon: Consultancy; Momenta: Honoraria, Speakers Bureau; Apellis: Speakers Bureau; Amgen: Honoraria, Speakers Bureau. Bianchi: Agios pharmaceutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Sica: Jazz Pharma: Consultancy; Alexion: Consultancy. Barcellini: Novartis: Other: Invited speaker, Research Funding; Agios: Membership on an entity's Board of Directors or advisory committees; Alexion Pharmaceuticals, Inc: Membership on an entity's Board of Directors or advisory committees, Other: Invited speaker, Research Funding; Bioverativ: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees.

Prevalence and Characteristics of Venous Thromboembolism in Patients with Complement Mediated Thrombotic Microangiopathy

BACKGROUND: Microvascular and arterial thromboses are well described in patients with thrombotic microangiopathy (TMA) including complement mediated TMA (CM-TMA)/atypical hemolytic uremic syndrome. Hemolytic disorders are associated with increased risk of venous thromboembolism (VTE), and patients with CM-TMA may have additional risk factors of hospitalization and central lines and may not consistently receive thromboprophylaxis due to thrombocytopenia. However, little is known about the prevalence and clinical correlates of VTE in CM-TMA. METHODS: We performed this single center retrospective cohort study of consecutive patients with CM-TMA enrolled in the Johns Hopkins Complement Associated Disease Registry between January 2014 and December 2020. Data regarding clinical presentation, laboratory studies including clinical complement gene sequencing, terminal complement inhibition and anticoagulation therapy, VTE events including characteristics and risk factors for VTE were collected. A diagnosis of CM-TMA was based on: (1) platelet count <150 × 10 9/L, (2) schistocytes on peripheral blood smear or TMA on renal biopsy, if performed, (3) ADAMTS13 activity >10%, (4) Shiga toxin negative, and (5) serum creatinine >2.25 mg/dL at presentation, which was considered supportive but not required for diagnosis. We only included VTE events post-CM-TMA diagnosis. VTE characteristics, treatment and outcomes were summarized using descriptive statistics. The Chi-squared test and Mann Whitney test were used to compare categorical and continuous variables across groups with and without VTE, respectively. RESULTS: Of 44 patients diagnosed with CM-TMA and followed for a median of 3.1 years (IQR 0.8-5.5), 8 (18.2%) experienced at total of 10 VTE events (5.6 VTE events/100 patient-years). There was no significant difference between patients with and without VTE in age at diagnosis, sex, race, BMI, need for dialysis, treatment with eculizumab, and presence of mutations in complement genes (Table 1). VTE events included 5 deep vein thromboses, 4 pulmonary emboli and 1 splenic infarct (Table 2). The majority (70%) of VTE events were provoked with 5 (50%) associated with a catheter or vascular access for dialysis and 2 (20%) events following major surgeries. The median time from CM-TMA diagnosis to the first VTE event was 4.9 months (IQR 0.76-26) with 3 events occurring during the index hospitalization for CM-TMA. Of 10 VTE events, 5 occurred while on complement inhibition and 2 on anticoagulation (1 on therapeutic and 1 on prophylactic anticoagulation). Of note, only 1 of 3 patients diagnosed with VTE during their index CM-TMA hospitalization received thromboprophylaxis. At the time of VTE diagnosis, the median platelet count was 182.5 x 10 9/L (IQR 143.75-332.75); 80% had a platelet count >150 x 10 9/L , and 10% each had a platelet count <50 x 10 9/L or 50-150 x 10 9/L. VTE was treated with therapeutic anticoagulation with enoxaparin, warfarin or a direct oral anticoagulant in 7 of 8 patients for a median duration of 7 months (IQR 4-14). One patient experienced recurrent PEs; the first PE occurred 2 months following the index CM-TMA hospitalization and the second event was 4 years later while off of anticoagulation and complement inhibition. A second patient experienced a splenic infarct 7 months after initial CM-TMA diagnosis while non-compliant with ravulizumab, followed by a catheter-associated upper extremity DVT 2 months later while on therapeutic anticoagulation and ravulizumab. No VTEs were fatal. CONCLUSION: VTE is common in patients with CM-TMA (18.2%), with a prevalence comparable to thrombotic thrombocytopenic purpura (18%, Tse et al. 2020) but greater than that reported in dialysis patients (Moinar et al. 2017). In CM-TMA patients, VTE is commonly provoked by hospitalization or dialysis catheters and tends to occur after platelet count recovery and in the absence of thromboprophylaxis. Factors such as renal impairment, prolonged hospitalization, complement dysregulation, and free hemoglobin release may also increase VTE risk. Our results highlight the high prevalence of VTE in CM-TMA and the importance of thromboprophylaxis once the platelet count is greater than 50 x 10 9/L. Figure 1 Figure 1. Disclosures Dane: Alexion: Honoraria; Sanofi Genzyme: Honoraria; Janssen: Honoraria. Chaturvedi: Sanofi Genzyme: Other: Advisory board member; Alexion: Other: Advisory board member; Dova: Other: Advisory board member; Argenx: Other: Advisory board member; UCB: Other: Advisory board participation.