Casirivimab/imdevimab for COVID-19: real-time analysis of all 9 studies

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Casirivimab/imdevimab (REGN-COV2) is an artificial "antibody cocktail" designed to produce resistance to the SARS-CoV-2 coronavirus. It consists of a mixture of two monoclonal antibodies. The combination of antibodies is intended to prevent mutational escape. Submit updates/corrections below.


6/23	Early	Webb et al., Open Forum Infectious Diseases, doi:10.1093/ofid/ofab331 (Peer Reviewed)	death, ↓98.3%, p=0.63	Real-World Effectiveness and Tolerability of Monoclonal Antibody Therapy for Ambulatory Patients with Early COVID-19
	Details Retrospective 115 patients treated with casirivimab/imdevimab showing lower mortality, hospital admission, and emergency department visits with treatment. Authors falsely state that "no other COVID-19 therapies for ambulatory patient..
6/23	Details Source PDF Early treatment study Early treatment study
	Webb et al., Open Forum Infectious Diseases, doi:10.1093/ofid/ofab331 (Peer Reviewed)
	Real-World Effectiveness and Tolerability of Monoclonal Antibody Therapy for Ambulatory Patients with Early COVID-19
	Retrospective 115 patients treated with casirivimab/imdevimab showing lower mortality, hospital admission, and emergency department visits with treatment. Authors falsely state that "no other COVID-19 therapies for ambulatory patients have proven effective". risk of death, 98.3% lower, RR 0.02, p = 0.63, treatment 0 of 115 (0.0%), control 57 of 5536 (1.0%), continuity correction due to zero event. risk of hospitalization, 91.1% lower, RR 0.09, p < 0.001, treatment 1 of 115 (0.9%), control 538 of 5536 (9.7%). Webb et al., 6/23/2021, retrospective, USA, North America, peer-reviewed, 14 authors.
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6/16	Late	Horby et al., medRxiv, doi:10.1101/2021.06.15.21258542 (Peer Reviewed)	death, ↓6.0%, p=0.17	Casirivimab and imdevimab in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial
	Details RCT 9,785 hospitalized patients in the UK showing lower mortality with casirivimab/imdevimab, with statistical significance reached for baseline seronegative patients.
6/16	Details Source PDF Late treatment study Late treatment study
	Horby et al., medRxiv, doi:10.1101/2021.06.15.21258542 (Peer Reviewed)
	Casirivimab and imdevimab in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial
	RCT 9,785 hospitalized patients in the UK showing lower mortality with casirivimab/imdevimab, with statistical significance reached for baseline seronegative patients. risk of death, 6.0% lower, RR 0.94, p = 0.17, treatment 944 of 4839 (19.5%), control 1026 of 4946 (20.7%), all patients. risk of mechanical ventilation, no change, RR 1.00, p = 1.00, treatment 479 of 4556 (10.5%), control 487 of 4642 (10.5%), all patients. risk of death, 20.0% lower, RR 0.80, p = 0.001, treatment 396 of 1633 (24.2%), control 451 of 1520 (29.7%), seronegative patients. risk of mechanical ventilation, 12.0% lower, RR 0.88, p = 0.18, treatment 189 of 1599 (11.8%), control 200 of 1484 (13.5%), seronegative patients. Horby et al., 6/16/2021, Randomized Controlled Trial, United Kingdom, Europe, peer-reviewed, 34 authors.
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5/21	Early	Weinreich et al., medRxiv, doi:10.1101/2021.05.19.21257469 (Preprint)	death, ↓67.0%, p=0.37	REGEN-COV Antibody Cocktail Clinical Outcomes Study in Covid-19 Outpatients
	Details RCT 4,057 outpatients with >=1 risk factor for severe disease, showing significantly lower combined hospitalization/death, and significantly faster recovery with treatment. Median time from onset of symptoms 3 days. NCT04425629.
5/21	Details Source PDF Early treatment study Early treatment study
	Weinreich et al., medRxiv, doi:10.1101/2021.05.19.21257469 (Preprint)
	REGEN-COV Antibody Cocktail Clinical Outcomes Study in Covid-19 Outpatients
	RCT 4,057 outpatients with >=1 risk factor for severe disease, showing significantly lower combined hospitalization/death, and significantly faster recovery with treatment. Median time from onset of symptoms 3 days. NCT04425629. risk of death, 67.0% lower, RR 0.33, p = 0.37, treatment 1 of 1355 (0.1%), control 3 of 1341 (0.2%), 2400mg. risk of death, 39.3% lower, RR 0.61, p = 1.00, treatment 1 of 736 (0.1%), control 3 of 1341 (0.2%), 1200mg. risk of combined hospitalization/death, 71.3% lower, RR 0.29, p < 0.001, treatment 18 of 1355 (1.3%), control 62 of 1341 (4.6%), 2400mg. risk of combined hospitalization/death, 70.4% lower, RR 0.30, p = 0.002, treatment 7 of 736 (1.0%), control 24 of 748 (3.2%), 1200mg. recovery time, 28.6% lower, relative time 0.71, p < 0.001, treatment 1355, control 1341, 2400mg. recovery time, 28.6% lower, relative time 0.71, p < 0.001, treatment 736, control 748, 1200mg. Weinreich et al., 5/21/2021, Randomized Controlled Trial, USA, North America, preprint, 39 authors.
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4/12	PEP	Regeneron Press Release (Preprint)	hosp./ER, ↓88.9%, p=0.06	Phase 3 prevention trial showed 81% reduced risk of symptomatic SARS-CoV-2 infections with subcutaneous administration of REGEN-COV™ (casirivimab and imdevimab)
	Details Press release for a phase 3 prophylaxis trial reporting lower hospitalization/ER and symptomatic cases, and faster recovery with 1,200mg subcutaneous casirivimab with imdevimab.
4/12	Details Source PDF Post Exposure Prophylaxis study Post Exposure Prophylaxis study
	Regeneron Press Release (Preprint)
	Phase 3 prevention trial showed 81% reduced risk of symptomatic SARS-CoV-2 infections with subcutaneous administration of REGEN-COV™ (casirivimab and imdevimab)
	Press release for a phase 3 prophylaxis trial reporting lower hospitalization/ER and symptomatic cases, and faster recovery with 1,200mg subcutaneous casirivimab with imdevimab. risk of hospitalization/ER, 88.9% lower, RR 0.11, p = 0.06, treatment 0 of 753 (0.0%), control 4 of 752 (0.5%), continuity correction due to zero event, day 29. risk of symptomatic case, 81.4% lower, RR 0.19, p < 0.001, treatment 11 of 753 (1.5%), control 59 of 752 (7.8%), day 29. recovery time, 62.5% lower, relative time 0.37, p < 0.001, treatment 753, control 752, relative time with symptoms. time to viral-, 69.2% lower, relative time 0.31, p < 0.001, treatment 753, control 752, relative time with high viral load. Regeneron et al., 4/12/2021, Double Blind Randomized Controlled Trial, preprint, 1 author.
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3/23	Early	Regeneron Press Release (Preprint)	hosp./death, ↓71.3%, p<0.0001	New phase III data shows investigational antibody cocktail casirivimab and imdevimab reduced hospitalisation or death by 70% in non-hospitalised patients with COVID-19
	Details Press release for new phase III data showing lower hospitalization/mortality, and faster symptom resolution among the subset of patients with at least one risk factor. Some variants may escape antibodies [1].
3/23	Details Source PDF Early treatment study Early treatment study
	Regeneron Press Release (Preprint)
	New phase III data shows investigational antibody cocktail casirivimab and imdevimab reduced hospitalisation or death by 70% in non-hospitalised patients with COVID-19
	Press release for new phase III data showing lower hospitalization/mortality, and faster symptom resolution among the subset of patients with at least one risk factor. Some variants may escape antibodies [1]. [1] cell.com/cell/fulltext/S0092-8674(21)00367-6 risk of combined hospitalization/death, 71.3% lower, RR 0.29, p < 0.001, treatment 18 of 1355 (1.3%), control 62 of 1341 (4.6%), 2,400mg IV, >=1 risk factor. risk of combined hospitalization/death, 70.4% lower, RR 0.30, p = 0.003, treatment 7 of 736 (1.0%), control 24 of 748 (3.2%), 1,200mg IV, >=1 risk factor. recovery time, 28.6% lower, relative time 0.71, p < 0.001, treatment 1355, control 1341, 2,400mg IV, >=1 risk factor. recovery time, 28.6% lower, relative time 0.71, p < 0.001, treatment 736, control 748, 1,200mg IV, >=1 risk factor. Regeneron et al., 3/23/2021, Randomized Controlled Trial, USA, North America, preprint, 1 author.
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1/26	PrEP	Regeneron Press Release (Preprint)	symp. case, ↓93.6%, p=0.009	Regeneron Reports Positive Interim Data with REGEN-COV™ Antibody Cocktail used as Passive Vaccine to Prevent COVID-19
	Details Interim results of REGEN-COV prophylaxis showing 100% prevention of symptomatic infection (8/223 placebo vs. 0/186 REGEN-COV), and approximately 50% lower overall rates of infection (symptomatic and asymptomatic) (23/223 placebo vs. 10/18..
1/26	Details Source PDF Pre-Exposure Prophylaxis study Pre-Exposure Prophylaxis study
	Regeneron Press Release (Preprint)
	Regeneron Reports Positive Interim Data with REGEN-COV™ Antibody Cocktail used as Passive Vaccine to Prevent COVID-19
	Interim results of REGEN-COV prophylaxis showing 100% prevention of symptomatic infection (8/223 placebo vs. 0/186 REGEN-COV), and approximately 50% lower overall rates of infection (symptomatic and asymptomatic) (23/223 placebo vs. 10/186 REGEN-COV). risk of symptomatic case, 93.6% lower, RR 0.06, p = 0.009, treatment 0 of 186 (0.0%), control 8 of 223 (3.6%), continuity correction due to zero event. risk of COVID-19 case, 47.9% lower, RR 0.52, p = 0.07, treatment 10 of 186 (5.4%), control 23 of 223 (10.3%). Regeneron et al., 1/26/2021, Randomized Controlled Trial, USA, North America, preprint, 1 author.
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9/29	Early	Regeneron Press Release (Preprint)	recov. time, ↓38.0%, p=0.22	Regeneron's REGN-COV2 antibody cocktail reduced viral levels and improved symptoms in non-hospitalized COVID-19 patients
	Details Analysis of the first 275 patients in a trial of the REGN-COV2 antibody cocktail showing reductions in viral load and the time to alleviate symptoms in non-hospitalized patients with COVID-19. Greatest improvements were seen with patients..
9/29	Details Source PDF Early treatment study Early treatment study
	Regeneron Press Release (Preprint)
	Regeneron's REGN-COV2 antibody cocktail reduced viral levels and improved symptoms in non-hospitalized COVID-19 patients
	Analysis of the first 275 patients in a trial of the REGN-COV2 antibody cocktail showing reductions in viral load and the time to alleviate symptoms in non-hospitalized patients with COVID-19. Greatest improvements were seen with patients that had not mounted their own effective immune response prior to treatment. The mean time-weighted-average change from baseline nasopharyngeal viral load through Day 7 in the seronegative (no measurable antiviral antibodies) group was a 0.60 log10 copies/mL greater reduction (p=0.03) in patients treated with high dose, and a 0.51 log10 copies/mL greater reduction (p=0.06) in patients treated with low dose, compared to placebo. In the overall population, there was a 0.51 log10 copies/mL greater reduction (p=0.0049) in patients treated with high dose, and a 0.23 log10 copies/mL greater reduction (p=0.20) in patients treated with low dose, compared to placebo. Among seronegative patients, median time to symptom alleviation (defined as symptoms becoming mild or absent) was 13 days in placebo, 8 days in high dose (p=0.22), and 6 days in low dose (p=0.09). Adverse reactions were similar with treatment and placebo. There were no deaths. recovery time, 38.0% lower, relative time 0.62, p = 0.22, treatment 92, control 91, high dose median time to recovery, group sizes estimated because they were not supplied. recovery time, 54.0% lower, relative time 0.46, p = 0.09, treatment 92, control 91, low dose median time to recovery, group sizes estimated because they were not supplied. Regeneron et al., 9/29/2020, Randomized Controlled Trial, preprint, 1 author.
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8/21	In Vitro	Baum et al., Science, 21 Aug 2020, 369:6506, 1014-1018, doi:10.1126/science.abd0831 (Peer Reviewed) (In Vitro)	in vitro	Antibody cocktail to SARS-CoV-2 spike protein prevents rapid mutational escape seen with individual antibodies
	Details In Vitro study showing that, under pressure from individual antibodies, mutant viruses were rapidly selected that evaded the blocking function of all individual antibodies tested, including antibodies that potently bind to highly-conserve..
8/21	Details Source PDF In Vitro In Vitro
	Baum et al., Science, 21 Aug 2020, 369:6506, 1014-1018, doi:10.1126/science.abd0831 (Peer Reviewed) (In Vitro)
	Antibody cocktail to SARS-CoV-2 spike protein prevents rapid mutational escape seen with individual antibodies
	In Vitro study showing that, under pressure from individual antibodies, mutant viruses were rapidly selected that evaded the blocking function of all individual antibodies tested, including antibodies that potently bind to highly-conserved regions on the spike protein. However, escape mutants could not be efficiently generated following exposure to the REGN-COV2 cocktail since it utilizes two antibodies that can simultaneously bind to distinct regions of the RBD. Baum et al., 8/21/2020, peer-reviewed, 17 authors.
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8/21	N/A	Hansen et al., Science, 21 Aug 2020, 369:6506, 1010-1014, doi:10.1126/science.abd0827 (Peer Reviewed)	animal study	Studies in humanized mice and convalescent humans yield a SARS-CoV-2 antibody cocktail
	Details Study using humanized mice and blood samples from recovered COVID-19 patients to generate antibodies targeting multiple different regions of the critical receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. The spike protein on ..
8/21	Details Source PDF N/A N/A
	Hansen et al., Science, 21 Aug 2020, 369:6506, 1010-1014, doi:10.1126/science.abd0827 (Peer Reviewed)
	Studies in humanized mice and convalescent humans yield a SARS-CoV-2 antibody cocktail
	Study using humanized mice and blood samples from recovered COVID-19 patients to generate antibodies targeting multiple different regions of the critical receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. The spike protein on the virus cell surface binds to the host cell and is required for infectivity. By blocking its interaction with the host cell, antibodies are able to neutralize the virus and block infection. Authors selected pairs of highly potent individual antibodies that simultaneously and non-competitively bind to the RBD. The multi-antibody approach is used to decrease the potential for the virus to escape. Hansen et al., 8/21/2020, peer-reviewed, 47 authors.
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