Subcutaneous REGEN-COV Antibody Combination to Prevent Covid-19.

BACKGROUND: REGEN-COV (previously known as REGN-COV2), a combination of the monoclonal antibodies casirivimab and imdevimab, has been shown to markedly reduce the risk of hospitalization or death among high-risk persons with coronavirus disease 2019 (Covid-19). Whether subcutaneous REGEN-COV prevents severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and subsequent Covid-19 in persons at high risk for infection because of household exposure to a person with SARS-CoV-2 infection is unknown. METHODS: We randomly assigned, in a 1:1 ratio, participants (≥12 years of age) who were enrolled within 96 hours after a household contact received a diagnosis of SARS-CoV-2 infection to receive a total dose of 1200 mg of REGEN-COV or matching placebo administered by means of subcutaneous injection. At the time of randomization, participants were stratified according to the results of the local diagnostic assay for SARS-CoV-2 and according to age. The primary efficacy end point was the development of symptomatic SARS-CoV-2 infection through day 28 in participants who did not have SARS-CoV-2 infection (as measured by reverse-transcriptase-quantitative polymerase-chain-reaction assay) or previous immunity (seronegativity). RESULTS: Symptomatic SARS-CoV-2 infection developed in 11 of 753 participants in the REGEN-COV group (1.5%) and in 59 of 752 participants in the placebo group (7.8%) (relative risk reduction [1 minus the relative risk], 81.4%; P<0.001). In weeks 2 to 4, a total of 2 of 753 participants in the REGEN-COV group (0.3%) and 27 of 752 participants in the placebo group (3.6%) had symptomatic SARS-CoV-2 infection (relative risk reduction, 92.6%). REGEN-COV also prevented symptomatic and asymptomatic infections overall (relative risk reduction, 66.4%). Among symptomatic infected participants, the median time to resolution of symptoms was 2 weeks shorter with REGEN-COV than with placebo (1.2 weeks and 3.2 weeks, respectively), and the duration of a high viral load (>104 copies per milliliter) was shorter (0.4 weeks and 1.3 weeks, respectively). No dose-limiting toxic effects of REGEN-COV were noted. CONCLUSIONS: Subcutaneous REGEN-COV prevented symptomatic Covid-19 and asymptomatic SARS-CoV-2 infection in previously uninfected household contacts of infected persons. Among the participants who became infected, REGEN-COV reduced the duration of symptomatic disease and the duration of a high viral load. (Funded by Regeneron Pharmaceuticals and others; ClinicalTrials.gov number, NCT04452318.).

REGEN-COV Antibody Combination and Outcomes in Outpatients with Covid-19.

BACKGROUND: In the phase 1-2 portion of an adaptive trial, REGEN-COV, a combination of the monoclonal antibodies casirivimab and imdevimab, reduced the viral load and number of medical visits in patients with coronavirus disease 2019 (Covid-19). REGEN-COV has activity in vitro against current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern. METHODS: In the phase 3 portion of an adaptive trial, we randomly assigned outpatients with Covid-19 and risk factors for severe disease to receive various doses of intravenous REGEN-COV or placebo. Patients were followed through day 29. A prespecified hierarchical analysis was used to assess the end points of hospitalization or death and the time to resolution of symptoms. Safety was also evaluated. RESULTS: Covid-19-related hospitalization or death from any cause occurred in 18 of 1355 patients in the REGEN-COV 2400-mg group (1.3%) and in 62 of 1341 patients in the placebo group who underwent randomization concurrently (4.6%) (relative risk reduction [1 minus the relative risk], 71.3%; P<0.001); these outcomes occurred in 7 of 736 patients in the REGEN-COV 1200-mg group (1.0%) and in 24 of 748 patients in the placebo group who underwent randomization concurrently (3.2%) (relative risk reduction, 70.4%; P = 0.002). The median time to resolution of symptoms was 4 days shorter with each REGEN-COV dose than with placebo (10 days vs. 14 days; P<0.001 for both comparisons). REGEN-COV was efficacious across various subgroups, including patients who were SARS-CoV-2 serum antibody-positive at baseline. Both REGEN-COV doses reduced viral load faster than placebo; the least-squares mean difference in viral load from baseline through day 7 was -0.71 log10 copies per milliliter (95% confidence interval [CI], -0.90 to -0.53) in the 1200-mg group and -0.86 log10 copies per milliliter (95% CI, -1.00 to -0.72) in the 2400-mg group. Serious adverse events occurred more frequently in the placebo group (4.0%) than in the 1200-mg group (1.1%) and the 2400-mg group (1.3%); infusion-related reactions of grade 2 or higher occurred in less than 0.3% of the patients in all groups. CONCLUSIONS: REGEN-COV reduced the risk of Covid-19-related hospitalization or death from any cause, and it resolved symptoms and reduced the SARS-CoV-2 viral load more rapidly than placebo. (Funded by Regeneron Pharmaceuticals and others; ClinicalTrials.gov number, NCT04425629.).

Casirivimab and Imdevimab for the Treatment of Hospitalized Patients With COVID-19.

BACKGROUND: The open-label RECOVERY study reported improved survival in hospitalized, SARS-CoV-2 seronegative patients treated with casirivimab and imdevimab (CAS + IMD). METHODS: In this phase 1/2/3, double-blind, placebo-controlled trial conducted prior to widespread circulation of Delta and Omicron, hospitalized COVID-19 patients were randomized (1:1:1) to 2.4 g or 8.0 g CAS + IMD or placebo, and characterized at baseline for viral load and SARS-CoV-2 serostatus. RESULTS: In total, 1336 patients on low-flow or no supplemental (low-flow/no) oxygen were treated. The primary endpoint was met in seronegative patients, the least-squares mean difference (CAS + IMD versus placebo) for time-weighted average change from baseline in viral load through day 7 was -0.28 log10 copies/mL (95% confidence interval [CI], -.51 to -.05; P = .0172). The primary clinical analysis of death or mechanical ventilation from day 6 to 29 in patients with high viral load had a strong positive trend but did not reach significance. CAS + IMD numerically reduced all-cause mortality in seronegative patients through day 29 (relative risk reduction, 55.6%; 95% CI, 24.2%-74.0%). No safety concerns were noted. CONCLUSIONS: In hospitalized COVID-19 patients on low-flow/no oxygen, CAS + IMD reduced viral load and likely improves clinical outcomes in the overall population, with the benefit driven by seronegative patients, and no harm observed in seropositive patients. CLINICAL TRIALS REGISTRATION: NCT04426695.

Lay Summary . Monoclonal antibody therapies that block the virus that causes COVID-19 (SARS-CoV-2) can prevent patients from being hospitalized. We hypothesized that these antibodies may also benefit patients who are already hospitalized with COVID-19. Therefore, we performed a study to determine if the monoclonal antibody combination of casirivimab and imdevimab (CAS + IMD) can decrease the amount of virus in the nose of hospitalized patients and prevent the disease from becoming more severe. The study, conducted from June 2020 to April 2021, found that CAS + IMD treatment reduced the amount of virus in these patients, and may reduce their chance of dying or needing a ventilator (a machine that helps patients breathe). Patients were examined in 2 groups: those whose immune systems, at the start of the study, had not produced their own antibodies to fight SARS-CoV-2 (seronegative patients); or those that had already produced their own antibodies (seropositive patients) at the start of the study. Seronegative patients benefited the most from CAS + IMD. No safety concerns related to CAS + IMD were observed. These results demonstrate that monoclonal antibody therapy can help hospitalized patients with COVID-19 and may decrease their chances of needing assistance to breathe or dying.

Effect of Subcutaneous Casirivimab and Imdevimab Antibody Combination vs Placebo on Development of Symptomatic COVID-19 in Early Asymptomatic SARS-CoV-2 Infection: A Randomized Clinical Trial.

Importance: Easy-to-administer anti-SARS-CoV-2 treatments may be used to prevent progression from asymptomatic infection to symptomatic disease and to reduce viral carriage. Objective: To evaluate the effect of combination subcutaneous casirivimab and imdevimab on progression from early asymptomatic SARS-CoV-2 infection to symptomatic COVID-19. Design, Setting, and Participants: Randomized, double-blind, placebo-controlled, phase 3 trial of close household contacts of a SARS-CoV-2-infected index case at 112 sites in the US, Romania, and Moldova enrolled July 13, 2020-January 28, 2021; follow-up ended March 11, 2021. Asymptomatic individuals (aged ≥12 years) were eligible if identified within 96 hours of index case positive test collection. Results from 314 individuals positive on SARS-CoV-2 reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) testing are reported. Interventions: Individuals were randomized 1:1 to receive 1 dose of subcutaneous casirivimab and imdevimab, 1200 mg (600 mg of each; n = 158), or placebo (n = 156). Main Outcomes and Measures: The primary end point was the proportion of seronegative participants who developed symptomatic COVID-19 during the 28-day efficacy assessment period. The key secondary efficacy end points were the number of weeks of symptomatic SARS-CoV-2 infection and the number of weeks of high viral load (>4 log10 copies/mL). Results: Among 314 randomized participants (mean age, 41.0 years; 51.6% women), 310 (99.7%) completed the efficacy assessment period; 204 were asymptomatic and seronegative at baseline and included in the primary efficacy analysis. Subcutaneous casirivimab and imdevimab, 1200 mg, significantly prevented progression to symptomatic disease (29/100 [29.0%] vs 44/104 [42.3%] with placebo; odds ratio, 0.54 [95% CI, 0.30-0.97]; P = .04; absolute risk difference, -13.3% [95% CI, -26.3% to -0.3%]). Casirivimab and imdevimab reduced the number of symptomatic weeks per 1000 participants (895.7 weeks vs 1637.4 weeks with placebo; P = .03), an approximately 5.6-day reduction in symptom duration per symptomatic participant. Treatment with casirivimab and imdevimab also reduced the number of high viral load weeks per 1000 participants (489.8 weeks vs 811.9 weeks with placebo; P = .001). The proportion of participants receiving casirivimab and imdevimab who had 1 or more treatment-emergent adverse event was 33.5% vs 48.1% for placebo, including events related (25.8% vs 39.7%) or not related (11.0% vs 16.0%) to COVID-19. Conclusions and Relevance: Among asymptomatic SARS-CoV-2 RT-qPCR-positive individuals living with an infected household contact, treatment with subcutaneous casirivimab and imdevimab antibody combination vs placebo significantly reduced the incidence of symptomatic COVID-19 over 28 days. Trial Registration: ClinicalTrials.gov Identifier: NCT04452318.

Population pharmacokinetic characteristics of cemiplimab in patients with advanced malignancies.

Cemiplimab, a human monoclonal antibody targeting programmed cell death-1 (PD-1) receptor, demonstrated antitumor activity in patients with advanced malignancies and a safety profile comparable to other anti-PD-1 therapies. This population pharmacokinetics (PopPK) analysis of cemiplimab included 11,178 pharmacokinetics (PK) observations from 548 patients pooled from a first-in-human study (Study 1423; NCT02383212) in advanced malignancies and a Phase 2 study (Study 1540; NCT02760498) in advanced cutaneous squamous cell carcinoma (CSCC). Most patients (80.3%) received cemiplimab 3 mg/kg every 2 weeks (Q2W) intravenously (IV). A PopPK model was developed by evaluating two-compartment linear models with an empirical non-linear function describing time-varying change in cemiplimab clearance and covariates that improved goodness-of-fit. PopPK simulations were used to describe cemiplimab exposure generated by a fixed 350 mg every 3 weeks (Q3W) IV dose regimen. PopPK modeling showed that a two-compartment model with zero-order IV infusion rate and first-order elimination rate well described individual concentrations of cemiplimab. Although several covariates, including baseline body weight and albumin concentrations, had a modest impact on cemiplimab exposure, the magnitude of influence was within the typical observed PK variability of approximately 30%. Based on PopPK simulation results, the 350 mg Q3W dose regimen was selected for further studies in advanced malignancies, including advanced CSCC. Similarity in observed cemiplimab exposure at the fixed 350 mg Q3W and the weight-based 3 mg/kg Q2W dose regimens confirmed this fixed dose selection. A robust PopPK model was developed to describe cemiplimab concentrations and supported use of the fixed 350 mg Q3W IV dose regimen.

A drug-disease model for predicting survival in an Ebola outbreak.

REGN-EB3 (Inmazeb) is a cocktail of three human monoclonal antibodies approved for treatment of Ebola infection. This paper describes development of a mathematical model linking REGN-EB3's inhibition of Ebola virus to survival in a non-human primate (NHP) model, and translational scaling to predict survival in humans. Pharmacokinetic/pharmacodynamic data from single- and multiple-dose REGN-EB3 studies in infected rhesus macaques were incorporated. Using discrete indirect response models, the antiviral mechanism of action was used as a forcing function to drive the reversal of key Ebola disease hallmarks over time, for example, liver and kidney damage (elevated alanine [ALT] and aspartate aminotransferases [AST], blood urea nitrogen [BUN], and creatinine), and hemorrhage (decreased platelet count). A composite disease characteristic function was introduced to describe disease severity and integrated with the ordinary differential equations estimating the time course of clinical biomarkers. Model simulation results appropriately represented the concentration-dependence of the magnitude and time course of Ebola infection (viral and pathophysiological), including time course of viral load, ALT and AST elevations, platelet count, creatinine, and BUN. The model estimated the observed survival rate in rhesus macaques and the dose of REGN-EB3 required for saturation of the pharmacodynamic effects of viral inhibition, reversal of Ebola pathophysiology, and survival. The model also predicted survival in clinical trials with appropriate scaling to humans. This mathematical investigation demonstrates that drug-disease modeling can be an important translational tool to integrate preclinical data from an NHP model recapitulating disease progression to guide future translation of preclinical data to clinical study design.

Translational findings for odronextamab: From preclinical research to a first-in-human study in patients with CD20+ B-cell malignancies.

Odronextamab is a fully-human IgG4-based CD20xCD3 bispecific antibody that binds to CD3 on T cells and CD20 on B cells, triggering T-cell-mediated cytotoxicity independent of T-cell-receptor recognition. Adequate safety, tolerability, and encouraging durable complete responses have been observed in an ongoing first-in-human (FIH) study of odronextamab in patients with relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma (B-NHL; NCT02290951). We retrospectively evaluated the pharmacokinetic, pharmacodynamic, and antitumor characteristics of odronextamab in a series of in vitro/in vivo preclinical experiments, to assess their translational value to inform dose escalation for the FIH study. Half-maximal effective concentration values from in vitro cytokine release assays (range: 0.05-0.08 mg/L) provided a reasonable estimate of odronextamab concentrations in patients associated with cytokine release at a 0.5 mg dose (maximum serum concentration: 0.081 mg/L) on week 1/day 1, which could therefore be used to determine the week 1 clinical dose. Odronextamab concentrations resulting in 100% inhibition of tumor growth in a Raji xenograft tumor mouse model (1-10 mg/L) were useful to predict efficacious concentrations in patients and inform dose-escalation strategy. Although predicted human pharmacokinetic parameters derived from monkey data overestimated projected odronextamab exposure, they provided a conservative estimate for FIH starting doses. With step-up dosing, the highest-tested weekly odronextamab dose in patients (320 mg) exceeded the 1 mg/kg single dose in monkeys without step-up dosing. In conclusion, combination of odronextamab in vitro cytokine data, efficacious concentration data from mouse tumor models, and pharmacokinetic evaluations in monkeys has translational value to inform odronextamab FIH study design in patients with R/R B-NHL.

Efficacy and safety of a single dose of casirivimab and imdevimab for the prevention of COVID-19 over an 8-month period: a randomised, double-blind, placebo-controlled trial.

BACKGROUND: There is an unmet need for COVID-19 prevention in patient populations who have not mounted or are not expected to mount an adequate immune response to complete COVID-19 vaccination. We previously reported that a single subcutaneous 1200 mg dose of the monoclonal antibody combination casirivimab and imdevimab (CAS + IMD) prevented symptomatic SARS-CoV-2 infections by 81·4% in generally healthy household contacts of SARS-CoV-2-infected individuals over a 1-month efficacy assessment period. Here we present additional results, including the 7-month follow-up period (months 2-8), providing additional insights about the potential for efficacy in pre-exposure prophylaxis settings. METHODS: This was a randomised, double-blind, placebo-controlled trial done in the USA, Romania, and Moldova in 2020-2021, before the emergence of omicron (B.1.1.529) and omicron-lineage variants. Uninfected and unvaccinated household contacts of infected individuals, judged by the investigator to be in good health, were randomly assigned (1:1) to receive 1200 mg CAS + IMD or placebo by subcutaneous injection according to a central randomisation scheme provided by an interactive web response system; randomisation was stratified per site by the test results of a local diagnostic assay for SARS-CoV-2 and age group at baseline. COVID-19 vaccines were prohibited before randomisation, but participants were allowed to receive COVID-19 vaccination during the follow-up period. Participants who developed COVID-19 symptoms during the follow-up period underwent RT-PCR testing. Prespecified endpoints included the proportion of previously uninfected and baseline-seronegative participants (seronegative-modified full analysis set) who had RT-PCR-confirmed COVID-19 in the follow-up period (post-hoc for the timepoints of months 2-5 and 6-8 only) and underwent seroconversion (ie, became seropositive, considered a proxy for any SARS-CoV-2 infections [symptomatic and asymptomatic]; prespecified up to day 57, post-hoc for all timepoints thereafter). We also assessed the incidence of treatment-emergent adverse events. This study is registered with ClinicalTrials.gov, NCT04452318. FINDINGS: From July 13, 2020, to Oct 4, 2021, 2317 participants who were RT-PCR-negative for SARS-CoV-2 were randomly assigned, of whom 1683 (841 assigned to CAS + IMD and 842 assigned to placebo) were seronegative at baseline. During the entirety of the 8-month study, CAS + IMD reduced the risk of COVID-19 by 81·2% (nominal p<0·0001) versus placebo (prespecified analysis). During the 7-month follow-up period, protection was greatest during months 2-5, with a 100% relative risk reduction in COVID-19 (nominal p<0·0001; post-hoc analysis). Efficacy waned during months 6-8 (post-hoc analysis). Seroconversion occurred in 38 (4·5%) of 841 participants in the CAS + IMD group and in 181 (21·5%) of 842 in the placebo group during the 8-month study (79·0% relative risk reduction vs placebo; nominal p<0·0001). Six participants in the placebo group were hospitalised due to COVID-19 versus none who received CAS + IMD. Serious treatment-emergent adverse events (including COVID-19) were reported in 24 (1·7%) of 1439 participants receiving CAS + IMD and in 23 (1·6%) of 1428 receiving placebo. Five deaths were reported, none of which were due to COVID-19 or related to the study drugs. INTERPRETATION: CAS + IMD is not authorised in any US region as of Jan 24, 2022, because data show that CAS + IMD is not active against omicron-lineage variants. In this study, done before the emergence of omicron-lineage variants, a single subcutaneous 1200 mg dose of CAS + IMD protected against COVID-19 for up to 5 months of community exposure to susceptible strains of SARS-CoV-2 in the pre-exposure prophylaxis setting, in addition to the post-exposure prophylaxis setting that was previously shown. FUNDING: Regeneron Pharmaceuticals, F Hoffmann-La Roche, US National Institute of Allergy and Infectious Diseases, US National Institutes of Health.

Virologic Efficacy of Casirivimab and Imdevimab COVID-19 Antibody Combination in Outpatients With SARS-CoV-2 Infection: A Phase 2 Dose-Ranging Randomized Clinical Trial.

Importance: The monoclonal antibody combination of casirivimab and imdevimab reduced viral load, hospitalization, or death when administered as a 1200-mg or greater intravenous (IV) dose in a phase 3 COVID-19 outpatient study. Subcutaneous (SC) and/or lower IV doses should increase accessibility and/or drug supplies for patients. Objective: To assess the virologic efficacy of casirivimab and imdevimab across different IV and SC doses compared with placebo. Design, Setting, and Participants: This phase 2, randomized, double-blind, placebo-controlled, parallel-group, dose-ranging study included outpatients with SARS-CoV-2 infection at 47 sites across the United States. Participants could be symptomatic or asymptomatic; symptomatic patients with risk factors for severe COVID-19 were excluded. Data were collected from December 15, 2020, to March 4, 2021. Interventions: Patients were randomized to a single IV dose (523 patients) of casirivimab and imdevimab at 300, 600, 1200, or 2400 mg or placebo; or a single SC dose (292 patients) of casirivimab and imdevimab at 600 or 1200 mg or placebo. Main Outcomes and Measures: The primary end point was the time-weighted average daily change from baseline (TWACB) in viral load from day 1 (baseline) through day 7 in patients seronegative for SARS-CoV-2 at baseline. Results: Among 815 randomized participants, 507 (282 randomized to IV treatment, 148 randomized to SC treatment, and 77 randomized to placebo) were seronegative at baseline and included in the primary efficacy analysis. Participants randomized to IV had a mean (SD) age of 34.6 (9.6) years (160 [44.6%] men; 14 [3.9%] Black; 121 [33.7%] Hispanic or Latino; 309 [86.1%] White); those randomized to SC had a mean age of 34.1 (10.0) years (102 [45.3%] men; 75 [34.7%] Hispanic or Latino; 6 [2.7%] Black; 190 [84.4%] White). All casirivimab and imdevimab treatments showed significant virologic reduction through day 7. Least-squares mean differences in TWACB viral load for casirivimab and imdevimab vs placebo ranged from -0.56 (95% CI; -0.89 to -0.24) log10 copies/mL for the 1200-mg IV dose to -0.71 (95% CI, -1.05 to -0.38) log10 copies/mL for the 2400-mg IV dose. There were no adverse safety signals or dose-related safety findings, grade 2 or greater infusion-related or hypersensitivity reactions, grade 3 or greater injection-site reactions, or fatalities. Two serious adverse events not related to COVID-19 or the study drug were reported. Conclusions and Relevance: In this randomized clinical trial including outpatients with asymptomatic and low-risk symptomatic SARS-CoV-2, all IV and SC doses of casirivimab and imdevimab comparably reduced viral load. Trial Registration: ClinicalTrials.gov Identifier: NCT04666441.

Pharmacokinetics and Pharmacodynamics of Subcutaneous Sarilumab and Intravenous Tocilizumab Following Single-Dose Administration in Patients With Active Rheumatoid Arthritis on Stable Methotrexate.

We assessed pharmacokinetics (PK), pharmacodynamics (PD), and PK/PD relationships of interleukin-6 (IL-6), soluble IL-6 receptor, and C-reactive protein (CRP) in serum, and absolute neutrophil count (ANC) in blood following single doses of subcutaneous sarilumab versus intravenous tocilizumab (NCT02097524) from patients with rheumatoid arthritis (RA) who are inadequate responders to methotrexate (MTX) and on a stable dose of MTX. Patients with RA randomized (1:1:1:1) to single-dose sarilumab (150 or 200 mg subcutaneously) or tocilizumab (4 or 8 mg/kg intravenously) were included (n = 101), and PK, PD, and PK/PD relationships and safety were assessed over 6 weeks postdose. PK profiles for both drugs are described by parallel linear and nonlinear target-mediated clearance pathways. PD markers showed similar onset of effect during the first week postdose, regardless of dose or route of administration. CRP and ANC decreased, with median postdose nadirs at 7-15 days for CRP and 3-5 days for ANC. Both drugs at low and high doses achieved the same nadir for ANC and a similar return toward baseline within 2 weeks postdose, suggesting a saturation of effect. Safety profiles of sarilumab and tocilizumab were generally similar. In conclusion, despite differences in PK, the onset of the decrease in CRP (efficacy) and ANC (safety) after a single dose were similar for subcutaneous sarilumab and intravenous tocilizumab. PD effects and safety were consistent with previous studies.

Base and Covariate Population Pharmacokinetic Analyses of Dupilumab in Adolescents and Children ≥6 to <12 Years of Age Using Phase 3 Data.

Population pharmacokinetic (PK) base and covariate analyses were conducted using data from adolescents with moderate-to-severe atopic dermatitis (AD) and children ≥6 to <12 years of age with severe AD. Two phase 3 studies were analyzed (165 adolescents and 241 children on active treatment). A 2-compartment model with linear and Michaelis-Menten elimination and 3 transit compartments describing lag time in absorption was utilized. Weight, albumin, body mass index, and Eczema Area and Severity Index score were statistically significant covariates in at least 1 of the age populations. Only body weight had a consequential effect on central volume. Although an absorption rate and target-mediated clearance somewhat decreased with age, no dose adjustment was needed in addition to the adjustment for weight already implemented in the phase 3 studies. Otherwise, population PK parameters and covariates were similar across the 2 pediatric subpopulations and in adults. No allometric changes in elimination rate and beta half-life were observed with weight. Parameterization of models in terms of rates was a useful alternative to parameterization in terms of clearances, allowing for an absence of repeated covariates and preventing overparameterization. The model adequately described dupilumab pharmacokinetics in the pediatric populations.

REGEN-COV® antibody cocktail bioanalytical strategy: comparison of LC-MRM-MS and immunoassay methods for drug quantification.

Aim: In response to the COVID-19 pandemic, Regeneron developed the anti-SARS-CoV-2 monoclonal antibody cocktail, REGEN-COV® (RONAPREVE® outside the USA). Drug concentration data was important for determination of dose, so a two-part bioanalytical strategy was implemented to ensure the therapy was rapidly available for use. Results & methodology: Initially, a liquid chromatography-multiple reaction monitoring-mass spectrometry (LC-MRM-MS) assay, was used to analyze early-phase study samples. Subsequently, a validated electrochemiluminescence (ECL) immunoassay was implemented for high throughput sample analysis for all samples. A comparison of drug concentration data from the methods was performed which identified strong linear correlations and for Bland-Altman, small bias. In addition, pharmacokinetic data from both methods produced similar profiles and parameters. Discussion & conclusion: This novel bioanalytical strategy successfully supported swift development of a critical targeted therapy during the COVID-19 public health emergency.

Subcutaneous REGEN-COV Antibody Combination in Early Asymptomatic SARS-CoV-2 Infection: A Randomized Clinical Trial.

IMPORTANCE: Easy-to-administer antiviral treatments may be used to prevent progression from asymptomatic infection to COVID-19 and to reduce viral carriage. OBJECTIVE: Evaluate the efficacy and safety of subcutaneous casirivimab and imdevimab antibody combination (REGEN-COV) to prevent progression from early asymptomatic SARS-CoV-2 infection to COVID-19. DESIGN: Randomized, double-blind, placebo-controlled, phase 3 study that enrolled asymptomatic close contacts living with a SARS-CoV-2-infected household member (index case). Participants who were SARS-CoV-2 RT-qPCR-positive at baseline were included in the analysis reported here. SETTING: Multicenter trial conducted at 112 sites in the United States, Romania, and Moldova. PARTICIPANTS: Asymptomatic individuals ≥12 years of age were eligible if identified within 96 hours of collection of the index case's positive SARS-CoV-2 test sample. INTERVENTIONS: A total of 314 asymptomatic, SARS-CoV-2 RT-qPCR-positive individuals living with an infected household contact were randomized 1:1 to receive a single dose of subcutaneous REGEN-COV 1200mg (n=158) or placebo (n=156). MAIN OUTCOMES AND MEASURES: The primary endpoint was the proportion of participants who developed symptomatic COVID-19 during the 28-day efficacy assessment period. The key secondary efficacy endpoints were the number of weeks of symptomatic SARS-CoV-2 infection and the number of weeks of high viral load (>4 log10 copies/mL). Safety was assessed in all treated participants. RESULTS: Subcutaneous REGEN-COV 1200mg significantly prevented progression from asymptomatic to symptomatic disease compared with placebo (31.5% relative risk reduction; 29/100 [29.0%] vs 44/104 [42.3%], respectively; P=.0380). REGEN-COV reduced the overall population burden of high-viral load weeks (39.7% reduction vs placebo; 48 vs 82 total weeks; P=.0010) and of symptomatic weeks (45.3% reduction vs placebo; 89.6 vs 170.3 total weeks; P=.0273), the latter corresponding to an approximately 5.6-day reduction in symptom duration per symptomatic participant. Six placebo-treated participants had a COVID-19-related hospitalization or ER visit versus none for those receiving REGEN-COV. The proportion of participants receiving placebo who had ≥1 treatment-emergent adverse events was 48.1% compared with 33.5% for those receiving REGEN-COV, including events related (39.7% vs 25.8%, respectively) or not related (16.0% vs 11.0%, respectively) to COVID-19. CONCLUSIONS AND RELEVANCE: Subcutaneous REGEN-COV 1200mg prevented progression from asymptomatic SARS-CoV-2 infection to COVID-19, reduced the duration of high viral load and symptoms, and was well tolerated. TRIAL REGISTRATION: ClinicalTrials.gov Identifier, NCT04452318.

Subcutaneous REGEN-COV Antibody Combination for Covid-19 Prevention.

Background: Casirivimab and imdevimab (REGEN-COV™) markedly reduces risk of hospitalization or death in high-risk individuals with Covid-19. Here we explore the possibility that subcutaneous REGEN-COV prevents SARS-CoV-2 infection and subsequent Covid-19 in individuals at high risk of contracting SARS-CoV-2 by close exposure in a household with a documented SARS-CoV-2-infected individual. Methods: Individuals ≥12 years were enrolled within 96 hours of a household contact being diagnosed with SARS-CoV-2 and randomized 1:1 to receive 1200 mg REGEN-COV or placebo via subcutaneous injection. The primary efficacy endpoint was the proportion of participants without evidence of infection (SARS-CoV-2 RT-qPCR-negative) or prior immunity (seronegative) who subsequently developed symptomatic SARS-CoV-2 infection during a 28-day efficacy assessment period. Results: Subcutaneous REGEN-COV significantly prevented symptomatic SARS-CoV-2 infection compared with placebo (81.4% risk reduction; 11/753 [1.5%] vs. 59/752 [7.8%], respectively; P<0.0001), with 92.6% risk reduction after the first week (2/753 [0.3%] vs. 27/752 [3.6%], respectively). REGEN-COV also prevented overall infections, either symptomatic or asymptomatic (66.4% risk reduction). Among infected participants, the median time to resolution of symptoms was 2 weeks shorter with REGEN-COV vs. placebo (1.2 vs. 3.2 weeks, respectively), and the duration of time with high viral load (>104 copies/mL) was lower (0.4 vs. 1.3 weeks, respectively). REGEN-COV was generally well tolerated. Conclusions: Administration of subcutaneous REGEN-COV prevented symptomatic Covid-19 and asymptomatic SARS-CoV-2 infection in uninfected household contacts of infected individuals. Among individuals who became infected, REGEN-COV reduced the duration of symptomatic disease, decreased maximal viral load, and reduced the duration of detectable virus.(ClinicalTrials.gov number, NCT04452318.).

Base and Covariate Population Pharmacokinetic Analyses of Dupilumab Using Phase 3 Data.

Population pharmacokinetic base and covariate models were developed to study functional dupilumab for regulatory submissions, using data from healthy volunteers and patients with moderate-to-severe atopic dermatitis (AD) receiving intravenous or subcutaneous doses. Sixteen studies were pooled (N = 2115; 202 healthy volunteers, 1913 AD patients). The best model was a 2-compartment model with linear and Michaelis-Menten elimination and 3 transit compartments describing absorption. A stepwise approach to model building, with some parameters estimated using mostly rich data and subsequently fixed, was used to avoid adverse effects of sparse data and a steep target-mediated phase on pharmacokinetic parameters, which require rich sampling for proper estimation. Parameterization of models in terms of rates was a useful alternative to the parameterization in terms of clearances, allowing for a reduced number of covariates while providing accurate predictions. While antidrug antibodies, albumin, race, body mass index, and Eczema Area and Severity Index score were statistically significant covariates, only body weight had a notable effect on central volume, explaining interindividual variability. The model adequately described dupilumab pharmacokinetics in phase 3 trials.

Population Pharmacodynamic Model of Neutrophil Margination and Tolerance to Describe Effect of Sarilumab on Absolute Neutrophil Count in Patients with Rheumatoid Arthritis.

Evidence suggests that effects of interleukin-6 pathway inhibitors sarilumab, tocilizumab, and sirukumab on absolute neutrophil count (ANC) are due to margination of circulating neutrophils into rapidly mobilizable noncirculating pools. We developed a population pharmacodynamic model using compartments for neutrophil margination and ANC-specific tolerance to describe rapid, transient ANC changes in blood following administration of subcutaneous sarilumab and intravenous/subcutaneous tocilizumab based on data from 322 patients with rheumatoid arthritis in two single-dose (NCT02097524 and NCT02404558) and one multiple-dose (NCT01768572) trials. The model incorporated a tolerance compartment to account for ANC nadir and beginning of recovery before maximal drug concentration after subcutaneous dosing, and absence of a nadir plateau when the ANC response is saturated after subcutaneous or intravenous dosing. The model effectively describes the ANC changes and supports neutrophil margination and tolerance as an explanation for the absence of increased infection risk associated with low ANC due to interleukin-6 pathway inhibitor treatment.

Pharmacodynamic relationship between PCSK9, alirocumab, and LDL-C lowering in the ODYSSEY CHOICE I trial.

BACKGROUND: The ODYSSEY CHOICE I study (NCT01926782) evaluated alirocumab 300 mg every 4 weeks (Q4W) in patients with hypercholesterolemia receiving maximally tolerated statin or no statin. OBJECTIVE: The objective of the study was to assess the relationship between alirocumab, proprotein convertase subtilisin/kexin type 9 (PCSK9), and low-density lipoprotein cholesterol (LDL-C) concentrations with the CHOICE I alirocumab dosing regimen. METHODS: This analysis included 803 patients (547 statin-treated, 256 without statin) who were randomized to alirocumab 300 mg Q4W, alirocumab 75 mg every 2 weeks (Q2W), or placebo. 300 mg Q4W and 75 mg Q2W doses were adjusted to 150 mg Q2W at Week 12 if Week 8 LDL-C was >70 or >100 mg/dL, depending on cardiovascular risk, or if LDL-C reduction was <30% from baseline. RESULTS: Most patients remained on 300 mg Q4W without dose adjustment as they achieved study-defined LDL-C goals at Week 8 (statin-treated: 80.7%; no statin: 85.3%). LDL-C was reduced by 60.5%-71.9% over Weeks 20-24 in patients on 300 mg Q4W and 57.2%-63.0% in patients with dose adjustment from 300 mg Q4W to 150 mg Q2W. Statin-treated patients had higher cardiovascular risk as well as higher free PCSK9 and lower alirocumab concentrations (vs no statin), suggesting increased target-mediated clearance. Regardless of statin status, the most common adverse events in alirocumab-treated patients were injection-site reaction and headache. CONCLUSIONS: Data provide further insight on alirocumab's mode of action in terms of relationship between alirocumab, PCSK9, and LDL-C, and disease severity, and support the use of alirocumab 300 mg Q4W as an efficacious dosing regimen for clinically meaningful LDL-C reductions.

Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability of Dupilumab in Healthy Adult Subjects.

Dupilumab is a fully human monoclonal antibody directed against the interleukin (IL)-4 receptor α subunit (IL-4Rα) of IL-4 heterodimeric type I and type II receptors that mediate IL-4/IL-13 signaling through this pathway. Blockade of these receptors broadly suppresses type 2 inflammation associated with atopic/allergic diseases, including atopic dermatitis and asthma. Six phase 1 studies investigated the pharmacokinetics, pharmacodynamics, safety, and tolerability of dupilumab in healthy subjects. Two randomized, double-blind, placebo-controlled, sequential studies assessed safety and tolerability of single escalating dupilumab doses administered intravenously or subcutaneously (one included various racial groups, and one included exclusively Japanese subjects); 3 randomized, parallel-group, single-dose studies compared the pharmacokinetic profiles of different dupilumab products and formulations after single subcutaneous doses; and one study assessed dupilumab administered as fast versus slow subcutaneous injections. Dupilumab concentrations in serum were measured in all studies, and total immunoglobulin E (IgE) and thymus- and activation-regulated chemokine (TARC) concentrations were measured in 2 studies as pharmacodynamic markers. Across the phase 1 studies, dupilumab exhibited target-mediated pharmacokinetics consisting of parallel linear and nonlinear elimination, with the target-mediated phase highly dominated by nonlinearity at lower drug concentrations. Systemic exposure and tolerability of dupilumab were consistent irrespective of differences in product, formulation, or racial background. Dupilumab reduced circulating concentrations of total IgE and TARC, indicating blockade of IL-4Rα-mediated signaling. Dupilumab had a favorable safety profile across the wide range of doses administered. Together, these findings support the continued development and use of dupilumab in treatment of type 2 diseases.

Population Pharmacokinetic Analysis of Alirocumab in Healthy Volunteers or Hypercholesterolemic Subjects Using a Michaelis-Menten Approximation of a Target-Mediated Drug Disposition Model-Support for a Biologics License Application Submission: Part I.

BACKGROUND: Alirocumab, a human monoclonal antibody, inhibits proprotein convertase subtilisin/kexin type 9 (PCSK9) to significantly reduce low-density lipoprotein cholesterol levels; pharmacokinetics (PK) are governed by non-linear, target-mediated drug disposition (TMDD). OBJECTIVES: We aimed to develop and qualify a population PK (PopPK) model to characterize the PK profile of alirocumab, evaluate the impact of covariates on alirocumab PK and on individual patient exposures, and estimate individual predicted concentrations for a subsequent PK/pharmacodynamic (PD) analysis. METHODS: Data from 13 phase I-III trials of 2799 healthy volunteers or patients with hypercholesterolemia treated with intravenous or subcutaneous alirocumab (13,717 alirocumab concentrations) were included; a Michaelis-Menten approximation of the TMDD model was used to estimate PK parameters and exposures. The final model comprised two compartments with first-order absorption. Elimination from the central compartment was described by linear (CLL) and non-linear Michaelis-Menten clearance (Vm and Km). The model was validated using visual predictive check and bootstrap methods. Patient exposures to alirocumab were computed using individual PK parameters. RESULTS: The PopPK model was well-qualified, with the majority of observed alirocumab concentrations in the 2.5th-97.5th predicted percentiles. Covariates responsible for interindividual variability were identified. Body weight and concomitant statin administration impacted CLL, whereas time-varying free PCSK9 concentrations and age affected Km and peripheral distribution volume (V3), respectively. No covariates were clinically meaningful, therefore no dose adjustments were needed. CONCLUSIONS: The model explained the between-subject variability, quantified the impact of covariates, and, finally, predicted alirocumab concentrations (subsequently used in a PopPK/PD model, see Part II) and individual exposures.

Pharmacokinetic and pharmacodynamic assessment of alirocumab in patients with familial hypercholesterolemia associated with proprotein convertase subtilisin/kexin type 9 gain-of-function or apolipoprotein B loss-of-function mutations.

BACKGROUND: Familial hypercholesterolemia is characterized by high levels of low-density lipoprotein cholesterol (LDL-C), and causes of familial hypercholesterolemia include apolipoprotein B (APOB) loss-of-function mutations (LOFm) and proprotein convertase subtilisin/kexin type 9 (PCSK9) gain-of-function mutations (GOFm). OBJECTIVE: The aim of this study was to compare the pharmacokinetics and pharmacodynamics of alirocumab between patients with APOB LOFm vs PCSK9 GOFm. METHODS: Patients (6 APOB LOFm and 17 PCSK9 GOFm carriers) with LDL-C ≥70 mg/dL on maximally tolerated lipid-lowering therapies received alirocumab 150 mg at Weeks 0, 2, 4, and 6, placebo at Week 8, alirocumab at Week 10, placebo at Weeks 12 and 14, then completed a follow-up period at Week 22. RESULTS: At Week 8, mean ± standard error (SE) alirocumab concentration was lower in APOB LOFm carriers compared with PCSK9 GOFm carriers (12.12 ± 1.81 vs 16.74 ± 2.53 mg/L). APOB LOFm carriers had higher mean ± SE total PCSK9 (6.56 ± 0.73 mg/L) and lower mean ± SE free PCSK9 (0.025 ± 0.016 mg/L) at Week 8 compared with PCSK9 GOFm carriers (4.21 ± 0.35 and 0.11 ± 0.035 mg/L for total and free PCSK9, respectively). Despite this observed greater PCSK9 suppression, mean ± SE percent LDL-C reduction was lower in APOB LOFm (55.3 ± 1.0%) compared with PCSK9 GOFm carriers (73.1 ± 0.9%). Treatment-emergent adverse events occurred in 16 patients (94.1%) in the PCSK9 GOFm group and 5 patients (83.3%) in the APOB LOFm group. CONCLUSIONS: Overall, PCSK9 inhibition with alirocumab results in clinically meaningful reductions in LDL-C in both APOB LOFm and PCSK9 GOFm carriers, although reductions were greater in the PCSK9 GOFm carriers. The results indicate a possible underlying contributor to hypercholesterolemia other than PCSK9 in patients with APOB LOFm. CLINICAL TRIAL REGISTRATION: NCT01604824; clinicaltrials.gov.