ALBERT

Description: INTRODUCTION: Blockade of complement factor C5 has demonstrated benefit in paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, generalized myasthenia gravis and neuromyelitis optica. We have completed a Phase I study of pozelimab, a fully human anti-C5 IgG4, in healthy volunteers. Pozelimab was well tolerated and resulted in dose-dependent inhibition of hemolytic activity through the classical complement pathway in normal healthy volunteers. Complete inhibition of hemolytic activity was maintained over a 4-week dosing period by a weekly subcutaneous (SC) regimen following an intravenous (IV) loading dose (ASH2018 abstract). OBJECTIVE: To further characterize the impact of pozelimab on the alternative complement pathway activity, we investigated the effect of pozelimab on alternative pathway-mediated hemolysis using an AH50 assay in the completed first-in-human (FIH) study. In addition, we compared the effect of pozelimab in both alternative and classical pathway hemolysis assays with those of in-house eculizumab and in-house ravulizumab in pooled normal human serum (NHS) samples, ex vivo. METHODS: In total, 56 subjects were randomized to 4 sequential ascending IV single dose cohorts plus 2 sequential ascending SC single dose cohorts followed by 1 multiple dose cohort (consisting of an IV loading dose and weekly SC doses). Each cohort consisted of 8 subjects randomized to receive pozelimab or placebo (6 active: 2 placebo). Serum collected at multiple time-points was utilized to assess the effect of pozelimab on alternative pathway activity. For ex vivo spike experiments, pooled NHS was used to compare the hemolytic function of pozelimab, in-house produced eculizumab and in-house produced ravulizumab. Comparator antibodies were synthesized from published sequence. The alternative pathway (AP) and classical pathway (CP) hemolysis assays were performed based on lysis of rabbit red blood cells (RBCs) and sensitized sheep RBCs, respectively. Both assays measure the amount of hemoglobin released from red blood cells at 412 nm. RESULTS: In the FIH study, baseline AH50 was comparable across treatment groups with a mean of 110 U/mL (standard deviation = 19, n = 56). Pozelimab exposure led to dose-dependent inhibition of AH50. In all 4 IV dosing cohorts, peak suppression of hemolysis was observed at end of infusion (EOI). Maximal suppression of hemolysis was approximately −85% change from baseline. This was achieved with the 30 mg/kg IV group and the repeat dose 15 mg/kg IV + 400 mg SC QW group. In the 2 SC cohorts, peak suppression of hemolysis was observed 3-7 days post dosing, which was consistent with observed peak concentrations of pozelimab in serum. In an ex vivo spike study, pozelimab, in-house eculizumab and in-house ravulizumab were spiked into 10, 25 or 48% pooled NHS for AP, and 5, 10 or 25% for CP. The results from AP hemolysis assays showed that, for a given concentration of spiked antibody, the maximal suppression of hemolysis for all the antibodies decreased with increased percentage of serum (Figure). The maximal suppression of hemolysis was consistently higher (32-169%) for pozelimab compared with in-house eculizumab, and lower for in-house ravulizumab compared with pozelimab and in-house eculizumab at all serum percentages tested. The results from CP hemolysis assays showed that, although the maximal suppression of hemolysis was similar for all antibodies tested, in-house ravulizumab was required to be at least a log higher in concentration to achieve a similar effect as the other two anti-C5 antibodies. CONCLUSIONS: Ex vivo studies with pooled NHS demonstrate that pozelimab robustly blocks both CP and AP hemolysis. In-house ravulizumab appeared to be less potent compared with in-house eculizumab in both CP and AP hemolysis assays. The Phase I healthy volunteer study of pozelimab demonstrated dose-dependent and significant inhibition of alternative pathway hemolysis, with the maximal suppression of hemolysis approximately −85% change from baseline. Figure Disclosures Devalaraja-Narashimha: Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Ni:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Huang:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Wang:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Chaudhari:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Prasad:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Harari:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Rankin:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Morton:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Weyne:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. OffLabel Disclosure: The drug is pozelimab and it is a fully human anti-C5 IgG4 being tested a Phase 1 study in healthy volunteers.

Description: Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired, life-threatening blood disease. While PNH is known to be a rare disease, the incidence and prevalence of the condition has been described only in a few small studies. In addition, while the International PNH registry is a rich source of data on real-world PNH patients globally, it is not possible to estimate the incidence and prevalence of PNH directly from the registry. As complement inhibitors are becoming the standard of care for PNH treatment, we also sought to explore how patients are managed following an incident PNH diagnosis. The objective of this study was to estimate the incidence and prevalence of PNH and to describe real-world treatment patterns among patients newly diagnosed with PNH in the United States (US). Methods: We conducted a retrospective cohort study using Truven US MarketScan Commercial/Medicare data (1 Jan 2015 to 30 June 2018), an employer-sponsored insurance claims database including annually approximately 30 million insured patients and their dependents' complete longitudinal records of inpatient services, outpatient services, and prescription drug claims covered under a variety of fee-for-service and capitated health plans. While these data are considered nationally representative of Americans with employer-provided health insurance, data come mainly from large employers. To estimate prevalence, we identified patients with ≥ 1 PNH diagnosis (ICD10: D59.5) among persons continually enrolled in the databases in 2017. To estimate incidence, we required ≥1-year of baseline enrolment and no PNH diagnosis or eculizumab exposure, identified using national drug codes [NDC] or procedure codes for drug administration, during the baseline period. Person-time accrued post-baseline until PNH diagnosis, end of study period, or disenrollment. We stratified incidence and prevalence estimates by age and sex and described patients with incident PNH in terms of demographics, comorbidities, and past-year healthcare resource utilization. Using Kaplan-Meier estimators, we estimated incidence of eculizumab initiation, timing of initiation, treatment duration, and risk of discontinuation/treatment holiday (〉42 days between eculizumab exposures [i.e. 14-day exposure period + 28-day grace period between infusions], the equivalent of missing 2 infusions assuming a bi-weekly infusion schedule for eculizumab) following the incident PNH diagnosis. While accounting for censoring, we also investigated patterns of red blood cell (RBC) transfusions, identified using procedure codes, in terms of incidence and timing of first transfusion following an incident PNH diagnosis. Results: The prevalence of PNH varied little between 2016 and 2017, from 12 to 13 per 1,000,000. The incidence rate over the study period was 5.7 per 1,000,000 person-years, representing 257 incident PNH cases. The incidence rate of PNH increased with age and was similar across sex. At diagnosis, mean age was 50.0 years (standard deviation [SD]: 18.6), 3.1% (8/257) were less than 18 years, 52.1% were women, 19.5% had a past-year diagnosis of aplastic anemia, 8.2% had a past-year diagnosis of myelodysplastic syndrome, 14.0% had a past-year RBC transfusion, and 31.5% had been hospitalized in the past-year. Over a mean follow-up time of 385.6 days (SD: 253.2), 10.3% (95% confidence interval [CI]: 6.3-14.1%) of patients initiated eculizumab on average 60.5 days (SD: 55.9) from PNH diagnosis. At 1 year, about one third of patients discontinued eculizumab or had taken a treatment holiday; average treatment duration was 328.2 days (SD:245.4). Cumulative incidence of RBC transfusions at 6 months and 1 year was 14.6% (10.1-18.9%) and 17.4% (12.2-22.3%), respectively. On average, the first RBC transfusion occurred within 63.6 days (SD: 114.4) of an incident PNH diagnosis. Conclusions: In routine clinical practice, only a minority of patients recently diagnosed with PNH are initiated on eculizumab. Among PNH patients treated with eculizumab, less than 70% remain on treatment after 1 year. Findings must be interpreted in the context of limitations including lack of information on clone size, symptom burden, measures of disease activity, or bone marrow failure state which may affect treatment course. Future studies should explore factors affecting eculizumab initiation and persistence on treatment. Disclosures Jalbert: Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Chaudhari:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Zhang:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Weyne:Regeneron Pharmaceuticals, Inc.: Employment, Equity Ownership. Shammo:Incyte: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Alexion: Consultancy, Honoraria, Research Funding, Speakers Bureau; Onconova: Research Funding; Apellis: Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Honoraria, Speakers Bureau; Astex Pharma: Research Funding; Novartis: Consultancy, Honoraria; Otsuka: Consultancy, Honoraria; CTI Pharma: Research Funding.

Description: INTRODUCTION: Blockade of complement factor C5 has demonstrated benefit in Paroxysmal Nocturnal Hemoglobinuria (PNH), atypical Hemolytic Uremic Syndrome and Generalized Myasthenia Gravis. We developed a human IgG4P antibody, REGN3918, that binds with high affinity to wild-type and variant (R885H/C) human C5. REGN3918 was well-tolerated in monkey toxicology studies with up to 26 weeks of dosing at up to 100 mg/kg/week. This finding was supportive of conducting this first-in-human study of REGN3918 in healthy volunteers. OBJECTIVE: The primary objective of this ongoing study is to evaluate the safety and tolerability of single ascending intravenous (IV) and subcutaneous (SC) doses and a multiple dose regimen consisting of an IV loading dose plus multiple weekly SC doses of REGN3918 administered in healthy volunteers. The secondary objectives of the study are to assess the pharmacokinetic (PK) and pharmacodynamic (PD) profile of REGN3918. METHODS: 56 subjects were randomized to 4 sequential ascending IV dose cohorts plus 2 sequential ascending SC cohorts followed by 1 multiple dose cohort (consisting of an IV loading dose and weekly SC doses). Each cohort consisted of 8 subjects randomized to receive REGN3918 or placebo (6 active: 2 placebo). An adaptive design was implemented to allow for dose level and dosing interval adjustment utilizing in-study PK and PD measures. The PD profile of REGN3918 was assessed utilizing a sheep red blood cell complement activity assay (CH50 assay) as well as serum concentrations of total C5. REGN3918 was administered as follows:Cohort 1: 1 mg/kg IV, single doseCohort 2a: 3 mg/kg IV, single doseCohort 2b: 300 mg SC, single doseCohort 3a: 10 mg/kg IV, single doseCohort 3b: 600 mg SC, single doseCohort 4: 30 mg/kg IV, single doseCohort 5: Loading dose of 15 mg/kg IV followed by 4 repeat SC doses of 400 mg administered once weekly for four weeks. RESULTS: REGN3918 was found to be well tolerated in single doses of up to 30 mg/kg IV and 600 mg SC. The multiple dose Cohort 5 has completed dosing in all subjects and is currently in safety follow-up. Thus far, there has been one SAE, salpingitis in a subject with an intra-uterine contraceptive device. The SAE occurred in a Cohort 5 subject after completion of dosing and has since resolved. REGN3918 exhibited dose-dependent increases in exposure in serum, with a trend toward prolonged serum concentrations at IV doses ≥10 mg/kg. Following SC administration, concentrations of REGN3918 in serum peaked at 4 to 8 days post dose and bioavailability was estimated as approximately 70%. REGN3918 exposure led to dose-dependent inhibition of CH50. In all 4 IV dosing cohorts, suppression of hemolysis was observed at 15 min post-injection. Complete suppression of hemolysis was achieved with ≥ 3mg/kg dosing. At 30 mg/kg, complete suppression of hemolysis was maintained for 〉6 weeks, consistent with observed prolonged REGN3918 concentrations following this dose. In the 2 SC cohorts, peak suppression of hemolysis was observed 3-7 days post dosing, again consistent with observed peak concentrations of REGN3918 in serum. In the multiple dose cohort 5, complete suppression of CH50 was observed over the four-week dosing period. CONCLUSIONS: REGN3918 was well tolerated and resulted in dose-dependent inhibition of hemolytic activity in normal healthy volunteers. A single IV infusion of R3918, at 30 mg/kg, blocked hemolytic activity completely for 〉6 weeks. Complete inhibition of hemolytic activity was maintained over a 4-week dosing period by a weekly SC regimen following an IV loading dose. Disclosures Weyne: Regeneron Pharmaceuticals: Employment, Equity Ownership. Ni:Regeneron Pharmaceuticals: Employment, Equity Ownership. DelGizzi:Regeneron Pharmaceuticals: Employment, Equity Ownership. Godin:Regeneron Pharmaceuticals: Employment. Morton:Regeneron Pharmaceuticals: Employment, Equity Ownership. Prasad:Regeneron Pharmaceuticals: Employment, Equity Ownership. Rankin:Regeneron Pharmaceuticals: Employment, Equity Ownership. Simek-Lemos:Regeneron Pharmaceuticals: Employment, Equity Ownership. Wang:Regeneron Pharmaceuticals: Employment, Equity Ownership. Rippley:Regeneron Pharmaceuticals: Employment, Equity Ownership. Harari:Regeneron Pharmaceuticals, Inc.: Employment.