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.

Repeat subcutaneous administration of casirivimab and imdevimab in adults is well-tolerated and prevents the occurrence of COVID-19

OBJECTIVES

A phase 1, double-blind, placebo-controlled trial was conducted to evaluate the safety, tolerability, and exploratory efficacy of repeat monthly doses of subcutaneous (SC) casirivimab and imdevimab (CAS+IMD) in uninfected adult volunteers.

METHODS

Participants were randomized (3:1) to SC CAS+IMD 1200 mg or placebo every 4 weeks for up to six doses. Primary and secondary end points evaluated safety, pharmacokinetics, and immunogenicity. Exploratory efficacy was evaluated by the incidence of COVID-19 or SARS-CoV-2 seroconversion.

RESULTS

In total, 969 participants received CAS+IMD. Repeat monthly dosing of SC CAS+IMD led to a 92.4% relative risk reduction in clinically defined COVID-19 compared with placebo (3/729 [0.4%] vs 13/240 [5.4%]; odds ratio 0.07 [95% CI 0.01-0.27]), and a 100% reduction in laboratory-confirmed COVID-19 (0/729 vs 10/240 [4.2%]; odds ratio 0.00). Development of anti-drug antibodies occurred in a small proportion of participants (<5%). No grade ≥3 injection-site reactions (ISRs) or hypersensitivity reactions were reported. Slightly more participants reported treatment-emergent adverse events with CAS+IMD (54.9%) than with placebo (48.3%), a finding that was due to grade 1-2 ISRs. Serious adverse events were rare. No deaths were reported in the 6-month treatment period.

CONCLUSION

Repeat monthly administration of 1200 mg SC CAS+IMD was well-tolerated, demonstrated low immunogenicity, and showed a substantial risk reduction in COVID-19 occurrence.

Efficacy and Safety of Sarilumab in Hospitalized Patients With Coronavirus Disease 2019: A Randomized Clinical Trial

BACKGROUND

Open-label platform trials and a prospective meta-analysis suggest efficacy of anti-interleukin (IL)-6R therapies in hospitalized patients with coronavirus disease 2019 (COVID-19) receiving corticosteroids. This study evaluated the efficacy and safety of sarilumab, an anti-IL-6R monoclonal antibody, in the treatment of hospitalized patients with COVID-19.

METHODS

In this adaptive, phase 2/3, randomized, double-blind, placebo-controlled trial, adults hospitalized with COVID-19 received intravenous sarilumab 400 mg or placebo. The phase 3 primary analysis population included patients with critical COVID-19 receiving mechanical ventilation (MV). The primary outcome was proportion of patients with ≥1-point improvement in clinical status from baseline to day 22.

RESULTS

There were 457 and 1365 patients randomized and treated in phases 2 and 3, respectively. In phase 3, patients with critical COVID-19 receiving MV (n = 298; 28.2% on corticosteroids), the proportion with ≥1-point improvement in clinical status (alive, not receiving MV) at day 22 was 43.2% for sarilumab and 35.5% for placebo (risk difference, +7.5%; 95% confidence interval [CI], -7.4 to 21.3; P =.3261), a relative risk improvement of 21.7%. In post hoc analyses pooling phase 2 and 3 critical patients receiving MV, the hazard ratio for death for sarilumab vs placebo was 0.76 (95% CI, .51 to 1.13) overall and 0.49 (95% CI, .25 to .94) in patients receiving corticosteroids at baseline.

CONCLUSIONS

This study did not establish the efficacy of sarilumab in hospitalized patients with severe/critical COVID-19. Post hoc analyses were consistent with other studies that found a benefit of sarilumab in patients receiving corticosteroids.

CLINICAL TRIALS REGISTRATION

NCT04315298.

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.

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.

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.

Compassionate Use of REGEN-COV ® in Patients with COVID-19 and Immunodeficiency-Associated Antibody Disorders

Background

Patients with immunodeficiency-associated antibody disorders are at a higher risk of prolonged/persistent COVID-19 infection, having no viable treatment options.

Methods

A retrospective analysis of patients with primary and/or secondary immunodeficiency-associated antibody disorders who received casirivimab and imdevimab (REGEN-COV^®) under emergency compassionate use. Objective were to describe safety and response to REGEN-COV, focusing on the subset of patients who had COVID-19 duration ≥21 days before treatment.

Results

Quantitative (change in oxygenation status and/or viral load) and/or qualitative (physician-reported clinical status) outcomes data are reported from 64 patients. Improvement in ≥1 outcome was observed in 90.6% of the overall patient group. Thirty-seven of these had COVID-19 duration ≥21 days before treatment; median time from diagnosis to REGEN-COV treatment was 60.5 days. Of the 29 patients with COVID-19 duration ≥21 days before treatment and available outcome data, 96.6% showed improvement in ≥1 outcome. In the 14 patients with post-treatment reverse transcription–polymerase chain reaction (RT-PCR) results available, 11 (78.6%) reported a negative RT-PCR following treatment, with 5 (45.5%) and 8 (72.7%) patients reporting a negative RT-PCR within 5 days and 21 days of treatment, respectively. Ten of 85 patients (11.8%) experienced serious adverse events; only one was an infusion-related reaction, possibly related to REGEN-COV. Two deaths were reported; neither were attributed to REGEN-COV.

Conclusions

In this retrospective analysis of immunodeficient patients granted REGEN-COV under emergency compassionate use, REGEN-COV treatment was associated with rapid viral clearance and clinical improvement in patients with longstanding COVID-19. Adverse events were consistent with COVID-19 and its associated complications, and due to patients’ concurrent medical conditions.

LB4. Casirivimab and Imdevimab for Treatment of Hospitalized Patients With COVID-19 Receiving Low Flow or No Supplemental Oxygen

Background

Casirivimab and imdevimab (CAS/IMDEV) is authorized for emergency use in the US for outpatients with COVID-19. We present results from patient cohorts receiving low flow or no supplemental oxygen at baseline from a phase 1/2/3, randomized, double-blinded, placebo (PBO)-controlled trial of CAS/IMDEV in hospitalized patients (pts) with COVID-19.

Methods

Hospitalized COVID-19 pts were randomized 1:1:1 to 2.4 g or 8.0 g of IV CAS/IMDEV (co-administered) or PBO. Primary endpoints were time-weighted average (TWA) change in viral load from baseline (Day 1) to Day 7; proportion of pts who died or went on mechanical ventilation (MV) through Day 29. Safety was evaluated through Day 57. The study was terminated early due to low enrollment (no safety concerns).

Results

Analysis was performed in pooled cohorts (low flow or no supplemental oxygen) as well as combined treatment doses (2.4 g and 8.0 g). The prespecified primary virologic analysis was in seronegative (seroneg) pts (combined dose group n=360; PBO n=160), where treatment with CAS/IMDEV led to a significant reduction in viral load from Day 1–7 (TWA change: LS mean (SE): -0.28 (0.12); 95% CI: -0.51, -0.05; P=0.0172; Fig. 1). The primary clinical analysis had a strong positive trend, though it did not reach statistical significance (P=0.2048), and 4/6 clinical endpoints prespecified for hypothesis testing were nominally significant (Table 1). In seroneg pts, there was a 47.0% relative risk reduction (RRR) in the proportion of pts who died or went on MV from Day 1–29 (10.3% treated vs 19.4% PBO; nominal P=0.0061; Fig. 2). There was a 55.6% (6.7% treated vs 15.0% PBO; nominal P=0.0032) and 35.9% (7.3% treated vs 11.5% PBO; nominal P=0.0178) RRR in the prespecified secondary endpoint of mortality by Day 29 in seroneg pts and the overall population, respectively (Fig. 2). No harm was seen in seropositive patients, and no safety events of concern were identified.

Figure 1: TWA daily viral load decreased from baseline (Day 1) in seronegative patients receiving low flow or no supplemental oxygen

Conclusion

Co-administration of CAS/IMDEV led to a significant reduction in viral load in hospitalized, seroneg pts requiring low flow or no supplemental oxygen. In seroneg pts and the overall population, treatment also demonstrated clinically meaningful, nominally significant reductions in 28-day mortality and proportion of pts dying or requiring MV.

Disclosures

Eleftherios Mylonakis, MD, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Chemic labs/KODA therapeutics (Grant/Research Support)Cidara (Grant/Research Support)Leidos Biomedical Research Inc/NCI (Grant/Research Support)NIH/NIAID (Grant/Research Support)NIH/NIGMS (Grant/Research Support)Pfizer (Grant/Research Support)Regeneron (Grant/Research Support)SciClone Pharmaceuticals (Grant/Research Support) Selin Somersan-Karakaya, MD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Sumathi Sivapalasingam, MD, BARDA (Other Financial or Material Support, HHSO100201700020C)Excision BioTherapeutics (Employee)Regeneron Pharmaceuticals, Inc. (Shareholder, Other Financial or Material Support, Royalties, patents planned, issued or pending, former employee) Shazia Ali, PharmD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Yiping Sun, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Rafia Bhore, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Jingning Mei, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Jutta Miller, BS, RN, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Lisa Cupelli, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee) Andrea T. Hooper, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Pfizer, Inc. (Shareholder, Other Financial or Material Support, Former employee)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder, Royalties, patents planned, issued or pending) Jennifer D. Hamilton, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder, Royalties, patents planned, issued or pending) Cynthia Pan, BPharm, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Viet Pham, BS, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Yuming Zhao, MS, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Romana Hosain, MD, MPH, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Adnan Mahmood, MD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) John D. Davis, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Kenneth C. Turner, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder, Royalties, patents planned, issued or pending) Yunji Kim, PharmD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Amanda Cook, BS, Dip Reg Aff, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Jason C. Wells, MD, BARDA (Other Financial or Material Support, HHSO100201700020C) Bari Kowal, MS, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Yuhwen Soo, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) A. Thomas DiCioccio, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Gregory P. Geba, MD, DrPH, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Shareholder) Neil Stahl, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder, Royalties, patents planned, issued or pending) Leah Lipsich, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Ned Braunstein, MD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder) Gary Herman, MD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder, Royalties, patents planned, issued or pending) George D. Yancopoulos, MD, PhD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder, Royalties, patents planned, issued or pending) David M. Weinreich, MD, BARDA (Other Financial or Material Support, HHSO100201700020C)Regeneron Pharmaceuticals, Inc. (Employee, Shareholder)

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.).

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.).

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.).

REGN-COV2, a Neutralizing Antibody Cocktail, in Outpatients with Covid-19

BACKGROUND

Recent data suggest that complications and death from coronavirus disease 2019 (Covid-19) may be related to high viral loads.

METHODS

In this ongoing, double-blind, phase 1-3 trial involving nonhospitalized patients with Covid-19, we investigated two fully human, neutralizing monoclonal antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein, used in a combined cocktail (REGN-COV2) to reduce the risk of the emergence of treatment-resistant mutant virus. Patients were randomly assigned (1:1:1) to receive placebo, 2.4 g of REGN-COV2, or 8.0 g of REGN-COV2 and were prospectively characterized at baseline for endogenous immune response against SARS-CoV-2 (serum antibody-positive or serum antibody-negative). Key end points included the time-weighted average change in viral load from baseline (day 1) through day 7 and the percentage of patients with at least one Covid-19-related medically attended visit through day 29. Safety was assessed in all patients.

RESULTS

Data from 275 patients are reported. The least-squares mean difference (combined REGN-COV2 dose groups vs. placebo group) in the time-weighted average change in viral load from day 1 through day 7 was -0.56 log10 copies per milliliter (95% confidence interval [CI], -1.02 to -0.11) among patients who were serum antibody-negative at baseline and -0.41 log10 copies per milliliter (95% CI, -0.71 to -0.10) in the overall trial population. In the overall trial population, 6% of the patients in the placebo group and 3% of the patients in the combined REGN-COV2 dose groups reported at least one medically attended visit; among patients who were serum antibody-negative at baseline, the corresponding percentages were 15% and 6% (difference, -9 percentage points; 95% CI, -29 to 11). The percentages of patients with hypersensitivity reactions, infusion-related reactions, and other adverse events were similar in the combined REGN-COV2 dose groups and the placebo group.

CONCLUSIONS

In this interim analysis, the REGN-COV2 antibody cocktail reduced viral load, with a greater effect in patients whose immune response had not yet been initiated or who had a high viral load at baseline. Safety outcomes were similar in the combined REGN-COV2 dose groups and the placebo group. (Funded by Regeneron Pharmaceuticals and the Biomedical and Advanced Research and Development Authority of the Department of Health and Human Services; ClinicalTrials.gov number, NCT04425629.).

Cardiovascular drug development: is it dead or just hibernating?

Despite the global burden of cardiovascular disease, investment in cardiovascular drug development has stagnated over the past 2 decades, with relative underinvestment compared with other therapeutic areas. The reasons for this trend are multifactorial, but of primary concern is the high cost of conducting cardiovascular outcome trials in the current regulatory environment that demands a direct assessment of risks and benefits, using clinically-evident cardiovascular endpoints. To work toward consensus on improving the environment for cardiovascular drug development, stakeholders from academia, industry, regulatory bodies, and government agencies convened for a think tank meeting in July 2014 in Washington, DC. This paper summarizes the proceedings of the meeting and aims to delineate the current adverse trends in cardiovascular drug development, understand the key issues that underlie these trends within the context of a recognized need for a rigorous regulatory review process, and provide potential solutions to the problems identified.

Human CD8+ T lymphocyte clones specific for T cell receptor V beta families expressed on autologous CD4+ T cells

CD8+ T cells control immune responses, and recent studies suggest that this regulation is, in part, specifically directed towards TCR structures expressed by CD4+ cells. To develop a system to study the role of the TCR in regulatory interactions, we isolated clones of CD4+ cells expressing identified TCR V beta chains. These CD4+ clones were used to stimulate and expand autologous CD8+ cells, which kill the inducing CD4+ clone as well as independently isolated autologous CD4+ clones sharing the same TCR V beta as the inducing cell but not CD4+ T cells expressing different V beta TCRs. This V beta-specific cytotoxicity is dependent on the state of activation of the target cells and is not inhibited by an anti-class I monoclonal antibody, W6/32. We envision that V beta-specific CD8+ T cells of this type may regulate immune responses by direct interaction with antigen-activated CD4+ cells.

Macrovascular and microvascular endothelium during long-term hypoxia: alterations in cell growth, monolayer permeability, and cell surface coagulant properties

In bovine aortic or capillary endothelial cells (ECs) incubated under hypoxic conditions, cell growth was slowed in a dose-dependent manner at lower oxygen concentrations, as progression into S phase from G1 was inhibited, concomitant with decreased thymidine kinase activity. Monolayers grown to confluence in ambient air, wounded, and then transferred to hypoxia showed decreased ability to repair the wound, as a result of both decreased motility and cell division. Hypoxic ECs demonstrated a approximately 3-fold increase in the total number of high-affinity fibroblast growth factor receptors, and levels of endogenous FGF were suppressed. Consistent with the presence of functional FGF receptors, addition of basic FGF overcame, at least in part, hypoxia-mediated suppression of EC growth, and enhanced wound repair in hypoxia, stimulating both motility and cell division. Despite slower growth in hypoxia, ECs could achieve confluence, and the monolayers consisted of larger cells with altered assembly of the actin-based cytoskeleton and small gaps between contiguous cells. The permeability of these hypoxic EC monolayers to macromolecules and lower molecular weight solutes was increased. Cell surface coagulant properties were also perturbed: the anticoagulant cofactor thrombomodulin was suppressed, and a novel Factor X activator appeared on the EC surface. These data indicate that micro- and macrovascular ECs can grow and be maintained at low oxygen tensions, but hypoxic endothelium exhibits a range of altered functional properties which can potentially contribute to the pathogenesis of vascular lesions.