Regdanvimab reduced COVID-19 risk: real-time meta analysis of 11 studies
Abstract
Significantly lower risk is seen for mortality, hospitalization, progression, and recovery. 10 studies from 7 independent teams (all from the same country) show significant
benefit.
Meta analysis using the most serious outcome reported shows
63% [51‑71%] lower risk. Results are similar for higher quality studies and worse for Randomized Controlled Trials.
Results are very robust — in exclusion sensitivity analysis 9 of
11 studies must be excluded to avoid finding statistically significant
efficacy in pooled analysis.
Efficacy is variant dependent. In Vitro research suggests a lack of efficacy for omicron BA.2, BA.4, BA.51, ХВВ.1.9.1, XBB.1.9.3, XBB.1.5.24, XBB.1.16, XBB.2.9, BQ.1.1.45, CL.1, and CH.1.12. mAb use may create new variants that spread globally3,4, and may be associated with prolonged viral loads, clinical deterioration, and immune escape4-7.
Regdanvimab for COVID-19 — Highlights
Regdanvimab reduces
risk with very high confidence for mortality, hospitalization, progression, and in pooled analysis, and high confidence for recovery.
35th treatment shown effective in
March 2022, now with p < 0.00000000001 from 11 studies, recognized in 27 countries.
Real-time updates
and corrections with a consistent protocol for 112 treatments. Outcome specific analysis and combined evidence from all
studies including treatment delay, a primary confounding factor.
Figure 1.
A. Random effects
meta-analysis. This plot shows pooled effects,
see the specific outcome analyses for individual outcomes.
Analysis validating pooled outcomes for
COVID-19 can be found below.
Effect extraction is pre-specified, using the most serious outcome reported.
For details see the appendix.
B. Timeline of results in regdanvimab studies. The marked dates indicate the time when efficacy was known with a statistically significant improvement of ≥10% from ≥3 studies for pooled outcomes and one or more specific outcome.
mAb treatments
AdintrevimabAmubarv../r..
Bamlaniv../e..
Bebtelovimab
Casirivimab/i..
Pemivibart
Ravulizumab
Regdanvimab
Siltuximab
Sotrovimab
Tixagev../c..
Vilobelimab
SARS-CoV-2 infection primarily begins in the upper respiratory
tract and may progress to the lower respiratory tract, other tissues, and the
nervous and cardiovascular systems, which may lead to cytokine storm,
pneumonia, ARDS, neurological injury8-19 and
cognitive deficits11,16, cardiovascular
complications20-23, organ failure, and death.
Minimizing replication as early as possible is recommended.
SARS-CoV-2 infection and replication involves the complex interplay of 50+
host and viral proteins and other factorsA,24-30, providing many
therapeutic targets for which many existing compounds have known activity.
Scientists have predicted that over 8,000 compounds may
reduce COVID-19 risk31, either by
directly minimizing infection or replication, by supporting immune system
function, or by minimizing secondary complications.
Regdanvimab is a monoclonal antibody (mAb). mAbs are laboratory-engineered proteins designed to mimic the immune system’s ability to fight pathogens. In the context of COVID-19, mAbs typically target specific regions of the SARS-CoV-2 spike protein, inhibiting viral entry into human cells and neutralizing the virus. These antibodies are derived from the B cells of recovered patients or immunized animals and are produced in large quantities using recombinant DNA technology and cell culture methods.
We analyze all significant
controlled studies of
regdanvimab
for COVID-19.
Search methods, inclusion criteria, effect extraction criteria (more serious
outcomes have priority), all individual study data, PRISMA answers, and
statistical methods are detailed in Appendix 1. We present random
effects meta-analysis results for all studies, studies within each treatment stage, individual outcomes, Randomized Controlled Trials (RCTs), and higher quality studies.
Figure 2 shows stages of possible treatment for
COVID-19. Prophylaxis refers to regularly taking medication before
becoming sick, in order to prevent or minimize infection. Early
Treatment refers to treatment immediately or soon after symptoms appear,
while Late Treatment refers to more delayed treatment.
Figure 2. Treatment stages.
Extensive mutations in SARS-CoV-2 have resulted in variants that evade neutralizing
antibodies from monoclonal antibody treatments32,33, resulting in efficacy
that is highly variant dependent.
Table 1 shows efficacy by variant for several monoclonal
antibodies. This table covers earlier SARS-CoV-2 variants and has not been
updated for more recent variants and more recent monoclonal antibodies.
| Bamlanivimab/ etesevimab |
Casirivimab/ imdevimab |
Sotrovimab | Bebtelovimab | Tixagevimab/ cilgavimab |
|
|---|---|---|---|---|---|
| Alpha B.1.1.7 | |||||
| Beta/ Gamma BA1.351/ P.1 | |||||
| Delta B.1.617.2 | |||||
| Omicron BA.1/ BA.1.1 | |||||
| Omicron BA.2 | |||||
| Omicron BA.5 | |||||
| Omicron BA.4.6 | |||||
| Omicron BQ.1.1 |
Table 2 summarizes the results for all stages combined, for Randomized Controlled Trials, after exclusions, and for specific outcomes.
Table 3 shows results by treatment stage.
Figure 3 plots individual results by treatment stage.
Figure 4, 5, 6, 7, 8, 9, 10, and 11
show forest plots for random effects meta-analysis of
all studies with pooled effects, mortality results, ventilation, ICU admission, hospitalization, progression, recovery, and viral clearance.
| Improvement | Studies | Patients | Authors | |
|---|---|---|---|---|
| All studies | 63% [51‑71%] **** | 11 | 7,430 | 118 |
| After exclusions | 64% [50‑74%] **** | 10 | 7,200 | 112 |
| Randomized Controlled TrialsRCTs | 10% [-511‑87%] | 2 | 1,622 | 41 |
| Mortality | 63% [37‑79%] *** | 7 | 3,945 | 73 |
| VentilationVent. | 48% [-91‑86%] | 4 | 2,124 | 68 |
| ICU admissionICU | 59% [-119‑93%] | 2 | 1,693 | 37 |
| HospitalizationHosp. | 15% [7‑21%] *** | 6 | 3,432 | 66 |
| Recovery | 41% [7‑63%] * | 4 | 2,017 | 33 |
| Viral | 19% [-17‑44%] | 2 | 1,537 | 41 |
| Early treatment | Late treatment | |
|---|---|---|
| All studies | 62% [50‑72%] **** | 86% [-156‑99%] |
| After exclusions | 64% [48‑74%] **** | 86% [-156‑99%] |
| Randomized Controlled TrialsRCTs | 10% [-511‑87%] | |
| Mortality | 62% [34‑78%] *** | 86% [-156‑99%] |
| VentilationVent. | 48% [-91‑86%] | |
| ICU admissionICU | 59% [-119‑93%] | |
| HospitalizationHosp. | 15% [7‑21%] *** | |
| Recovery | 41% [7‑63%] * | |
| Viral | 19% [-17‑44%] |
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Figure 3. Scatter plot showing the most serious outcome in all studies, and for studies within each stage. Diamonds shows the results of random effects meta-analysis.
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Figure 4. Random effects meta-analysis for all studies.
This plot shows pooled effects,
see the specific outcome analyses for individual outcomes.
Analysis validating pooled outcomes for
COVID-19 can be found below.
Effect extraction is pre-specified, using the most serious outcome reported.
For details see the appendix.
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Figure 5. Random effects meta-analysis for mortality results.
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Figure 6. Random effects meta-analysis for ventilation.
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Figure 7. Random effects meta-analysis for ICU admission.
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Figure 8. Random effects meta-analysis for hospitalization.
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Figure 9. Random effects meta-analysis for progression.
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Figure 10. Random effects meta-analysis for recovery.
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Figure 11. Random effects meta-analysis for viral clearance.
Figure 12 shows a comparison of results for RCTs and non-RCT studies.
Figure 13 and 14
show forest plots for random effects meta-analysis of
all Randomized Controlled Trials and RCT mortality results.
RCT results are included in Table 2 and Table 3.
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Figure 12. Results for RCTs and non-RCT studies.
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Figure 13. Random effects meta-analysis for all Randomized Controlled Trials.
This plot shows pooled effects,
see the specific outcome analyses for individual outcomes.
Analysis validating pooled outcomes for
COVID-19 can be found below.
Effect extraction is pre-specified, using the most serious outcome reported.
For details see the appendix.
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Figure 14. Random effects meta-analysis for RCT mortality results.
RCTs help to make study groups more similar and can provide a higher level of
evidence, however they are subject to many biases35, and
analysis of double-blind RCTs has identified extreme levels of bias36.
For COVID-19, the overhead may delay treatment, dramatically compromising
efficacy; they may encourage monotherapy for simplicity at the cost of
efficacy which may rely on combined or synergistic effects; the participants
that sign up may not reflect real world usage or the population that benefits
most in terms of age, comorbidities, severity of illness, or other factors;
standard of care may be compromised and unable to evolve quickly based on
emerging research for new diseases; errors may be made in randomization and
medication delivery; and investigators may have hidden agendas or vested
interests influencing design, operation, analysis, reporting, and the
potential for fraud. All of these biases have been observed with COVID-19
RCTs. There is no guarantee that a specific RCT provides a higher level of
evidence.
RCTs are expensive and many RCTs are funded
by pharmaceutical companies or interests closely aligned with pharmaceutical
companies. For COVID-19, this creates an incentive to show efficacy for
patented commercial products, and an incentive to show a lack of efficacy for
inexpensive treatments. The bias is expected to be significant, for example
Als-Nielsen et al. analyzed 370 RCTs from Cochrane reviews, showing that
trials funded by for-profit organizations were 5 times more likely to
recommend the experimental drug compared with those funded by nonprofit
organizations. For COVID-19, some major philanthropic organizations are
largely funded by investments with extreme conflicts of interest for and
against specific COVID-19 interventions.
High quality RCTs for novel acute diseases are more challenging, with
increased ethical issues due to the urgency of treatment, increased risk due
to enrollment delays, and more difficult design with a rapidly evolving
evidence base. For COVID-19, the most common site of initial infection is the
upper respiratory tract. Immediate treatment is likely to be most successful
and may prevent or slow progression to other parts of the body. For a
non-prophylaxis RCT, it makes sense to provide treatment in advance and
instruct patients to use it immediately on symptoms, just as some governments
have done by providing medication kits in advance. Unfortunately, no RCTs have
been done in this way. Every treatment RCT to date involves delayed treatment.
Among the 112 treatments we have analyzed,
66% of RCTs involve very late treatment 5+ days after
onset. No non-prophylaxis COVID-19 RCTs match the potential real-world use of
early treatments. They may more accurately represent results for treatments
that require visiting a medical facility, e.g., those requiring intravenous
administration.
For COVID-19, observational study results do not systematically
differ from RCTs, RR 1.00 [0.92‑1.08]
across 112 treatments38.
Evidence shows that observational studies
can also provide reliable results. Concato et al. found that well-designed
observational studies do not systematically overestimate the magnitude of the
effects of treatment compared to RCTs. Anglemyer et al. analyzed reviews
comparing RCTs to observational studies and found little evidence for
significant differences in effect estimates.
We performed a similar analysis across the 112 treatments
we cover, showing no significant difference in the results of RCTs compared to
observational studies, RR 1.00 [0.92‑1.08]. Similar results are found for all low-cost treatments, RR
1.02 [0.92‑1.12]. High-cost treatments
show a non-significant trend towards RCTs showing greater efficacy,
RR 0.92 [0.82‑1.03].
Details can be found in the
supplementary data.
Lee et al. showed that only 14% of the guidelines of the Infectious
Diseases Society of America were based on RCTs. Evaluation of studies relies
on an understanding of the study and potential biases. Limitations in an RCT
can outweigh the benefits, for example excessive dosages, excessive treatment
delays, or remote survey bias may have a greater effect on results. Ethical
issues may also prevent running RCTs for known effective treatments. For more
on issues with RCTs see42,43.
Currently, 48 of the treatments we analyze show statistically significant efficacy or harm, defined as ≥10% decreased risk or >0% increased risk from ≥3 studies. Of these, 60% have been confirmed in RCTs, with a mean delay of 7.1 months (68% with 8.2 months delay for low-cost treatments). The remaining treatments either have no RCTs, or the point estimate is consistent.
We need to evaluate each trial on its own merits. RCTs for a
given medication and disease may be more reliable, however they may also be
less reliable. For off-patent medications, very high conflict of interest
trials may be more likely to be RCTs, and more likely to be large trials that
dominate meta analyses.
To avoid bias in the selection of studies, we analyze all
non-retracted studies. Here we show the results after excluding
studies with major issues likely to alter results, non-standard studies, and
studies where very minimal detail is currently available. Our bias evaluation
is based on analysis of each study and identifying when there is a significant
chance that limitations will substantially change the outcome of the study. We
believe this can be more valuable than checklist-based approaches such as
Cochrane GRADE, which can be easily influenced by potential bias, may ignore
or underemphasize serious issues not captured in the checklists, and may
overemphasize issues unlikely to alter outcomes in specific cases (for example
certain specifics of randomization with a very large effect size and
well-matched baseline characteristics).
The studies excluded are as below.
Figure 15 shows a forest plot for random
effects meta-analysis of all studies after exclusions.
Lee (B), minimal details provided.
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Figure 15. Random effects meta-analysis for all studies after exclusions.
This plot shows pooled effects,
see the specific outcome analyses for individual outcomes.
Analysis validating pooled outcomes for
COVID-19 can be found below.
Effect extraction is pre-specified, using the most serious outcome reported.
For details see the appendix.
Heterogeneity in COVID-19 studies arises from many factors including:
The time between infection or the onset of symptoms and
treatment may critically affect how well a treatment works. For example an
antiviral may be very effective when used early but may not be effective in
late stage disease, and may even be harmful. Oseltamivir, for example, is
generally only considered effective for influenza when used within 0-36 or
0-48 hours45,46. Baloxavir marboxil studies for influenza
also show that treatment delay is critical — Ikematsu et al. report
an 86% reduction in cases for post-exposure prophylaxis, Hayden et al.
show a 33 hour reduction in the time to alleviation of symptoms for treatment
within 24 hours and a reduction of 13 hours for treatment within 24-48 hours,
and Kumar et al. report only 2.5 hours improvement for inpatient
treatment.
| Treatment delay | Result |
| Post-exposure prophylaxis | 86% fewer cases47 |
| <24 hours | -33 hours symptoms48 |
| 24-48 hours | -13 hours symptoms48 |
| Inpatients | -2.5 hours to improvement49 |
Figure 16 shows a mixed-effects meta-regression for efficacy
as a function of treatment delay in COVID-19 studies from 112 treatments, showing
that efficacy declines rapidly with treatment delay. Early treatment is
critical for COVID-19.
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Figure 16. Early treatment is more effective. Meta-regression showing efficacy as a function of treatment delay in COVID-19 studies from 112 treatments.
Details of the patient population including age and comorbidities may
critically affect how well a treatment works. For example, many COVID-19
studies with relatively young low-comorbidity patients show all patients
recovering quickly with or without treatment. In such cases, there is little
room for an effective treatment to improve results, for example as in
López-Medina et al.
Efficacy may depend critically on the distribution of
SARS-CoV-2 variants encountered by patients. Risk varies significantly across
variants51, for example the Gamma variant shows significantly
different characteristics52-55. Different
mechanisms of action may be more or less effective depending on variants, for
example the degree to which TMPRSS2 contributes to viral entry can differ
across variants56,57.
Effectiveness may depend strongly on the dosage and treatment regimen.
The quality of medications may vary significantly between
manufacturers and production batches, which may significantly affect efficacy
and safety. Williams et al. analyze ivermectin from 11 different sources,
showing highly variable antiparasitic efficacy across different manufacturers.
Xu et al. analyze a treatment from two different manufacturers, showing 9
different impurities, with significantly different concentrations for each
manufacturer.
Across all
studies there is a strong association between different outcomes, for example
improved recovery is strongly associated with lower mortality. However,
efficacy may differ depending on the effect measured, for example a treatment
may be more effective against secondary complications and have minimal effect
on viral clearance.
The
distribution of studies will alter the outcome of a meta analysis. Consider a
simplified example where everything is equal except for the treatment delay,
and effectiveness decreases to zero or below with increasing delay. If there
are many studies using very late treatment, the outcome may be negative, even
though early treatment is very effective.
All meta analyses combine heterogeneous studies, varying in population,
variants, and potentially all factors above, and therefore may obscure
efficacy by including studies where treatment is less effective. Generally, we
expect the estimated effect size from meta analysis to be less than that for
the optimal case.
Looking at all studies is valuable for providing an overview of all research,
important to avoid cherry-picking, and informative when a positive result is
found despite combining less-optimal situations. However, the resulting
estimate does not apply to specific cases such as
early treatment in high-risk populations.
While we present results for all studies, we also present treatment time and
individual outcome analyses, which may be more informative for specific use
cases.
This section validates the use of pooled effects for COVID-19, which enables
earlier detection of efficacy, however pooled effects are no longer required
for regdanvimab as of March 2022. Efficacy is now known based on specific outcomes.
For COVID-19, delay in clinical results translates into
additional death and morbidity, as well as additional economic and societal
damage. Combining the results of studies reporting different outcomes is
required.
There may be no mortality in a trial with low-risk patients,
however a reduction in severity or improved viral clearance may translate
into lower mortality in a high-risk population.
Different studies may report lower severity, improved recovery, and lower mortality,
and the significance may be very high when combining the results.
"The studies reported different outcomes" is not a good reason for
disregarding results.
Pooling the results of studies reporting different outcomes allows us to use
more of the available information. Logically we should, and do, use additional
information when evaluating treatments—for example dose-response and
treatment delay-response relationships provide additional evidence of efficacy
that is considered when reviewing the evidence for a treatment.
We present both specific outcome and pooled analyses.
In order to combine the results of studies reporting different outcomes we use
the most serious outcome reported in each study, based on the thesis that
improvement in the most serious outcome provides comparable measures of
efficacy for a treatment. A critical advantage of this approach is
simplicity and transparency.
There are many other ways to combine evidence for different outcomes, along
with additional evidence such as dose-response relationships, however these
increase complexity.
Trials with high-risk patients may be restricted due to ethics for treatments
that are known or expected to be effective, and they increase difficulty for
recruiting. Using less severe outcomes as a proxy for more serious outcomes
allows faster and safer collection of evidence.
For many COVID-19 treatments, a reduction in mortality logically
follows from a reduction in hospitalization, which follows from a reduction in
symptomatic cases, which follows from a reduction in PCR positivity. We can
directly test this for COVID-19.
Analysis of the the association between different outcomes across studies from
all 112
treatments we cover confirms the validity of pooled outcome analysis for COVID-19.
Figure 17 shows that lower hospitalization is very strongly associated
with lower mortality (p < 0.000000000001).
Similarly, Figure 18 shows that improved recovery is very strongly associated
with lower mortality (p < 0.000000000001).
Considering the extremes, Singh et al. show an association between viral clearance and
hospitalization or death, with p = 0.003 after excluding one large
outlier from a mutagenic treatment, and based on 44 RCTs including 52,384
patients.
Figure 19 shows that improved viral clearance is strongly associated
with fewer serious outcomes. The association is very similar to
Singh et al., with higher confidence due to the larger number of
studies. As with Singh et al., the confidence increases
when excluding the outlier treatment, from p = 0.00000032 to p = 0.000000011.
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Figure 17. Lower hospitalization is associated with lower mortality, supporting pooled outcome analysis.
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Figure 18. Improved recovery is associated with lower mortality, supporting pooled outcome analysis.
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Figure 17. Improved viral clearance is associated with fewer serious outcomes, supporting pooled outcome analysis.
Currently, 48 of the treatments we analyze show statistically significant efficacy or harm, defined as ≥10% decreased risk or >0% increased risk from ≥3 studies. 89% of these have been confirmed with one or more specific outcomes, with a mean delay of 5.0 months. When restricting to RCTs only, 56% of treatments showing statistically significant efficacy/harm with pooled effects have been confirmed with one or more specific outcomes, with a mean delay of 6.4 months.
Figure 20 shows when treatments were found effective during the
pandemic. Pooled outcomes often resulted in earlier detection of efficacy.
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Figure 20. The time when studies showed that
treatments were effective, defined as statistically significant improvement of
≥10% from ≥3 studies.
Pooled results typically show efficacy earlier than specific
outcome results. Results from all studies often shows efficacy much earlier
than when restricting to RCTs.
Results reflect conditions as used in trials to date, these depend on the
population treated, treatment delay, and treatment regimen.
Pooled analysis could hide efficacy, for example a treatment that is
beneficial for late stage patients but has no effect on viral clearance may
show no efficacy if most studies only examine viral clearance. In practice, it
is rare for a non-antiviral treatment to report viral clearance and to not
report clinical outcomes; and in practice other sources of heterogeneity such
as difference in treatment delay is more likely to hide efficacy.
Analysis validates the use of pooled effects and shows significantly faster
detection of efficacy on average.
However, as with all meta analyses, it is important to review the different
studies included. We also present individual outcome analyses, which may be
more informative for specific use cases.
Publishing is often biased
towards positive results. Trials with patented drugs may have a financial conflict of interest that
results in positive studies being more likely to be published, or bias towards more positive results. For example with molnupiravir, trials with negative results remain unpublished to
date (CTRI/2021/05/033864 and CTRI/2021/08/0354242).
For regdanvimab, there is currently not
enough data to evaluate publication bias with high confidence.
One method to evaluate bias is to compare prospective vs.
retrospective studies. Prospective studies are more likely to be published
regardless of the result, while retrospective studies are more likely to
exhibit bias. For example, researchers may perform preliminary analysis with
minimal effort and the results may influence their decision to continue.
Retrospective studies also provide more opportunities for the specifics of
data extraction and adjustments to influence results.
Figure 21 shows a scatter plot of
results for prospective and retrospective studies.
Prospective studies show 10% [-511‑87%] improvement in meta
analysis, compared to 64% [51‑73%] for retrospective
studies, suggesting possible positive publication bias, with a non-significant trend towards retrospective studies
reporting higher efficacy.
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Figure 21. Prospective vs. retrospective studies.
The diamonds show the results of random effects meta-analysis.
Studies for regdanvimab were primarily for early treatment, in contrast
with typical low cost treatments that were mostly tested with late treatment.
Figure 22. Patented treatments received mostly early treatment studies, while low cost treatments were typically tested for late treatment.
Funnel
plots have traditionally been used for analyzing publication bias. This is
invalid for COVID-19 acute treatment trials — the underlying assumptions
are invalid, which we can demonstrate with a simple example. Consider a set of
hypothetical perfect trials with no bias. Figure 23 plot A
shows a funnel plot for a simulation of 80 perfect trials, with random group
sizes, and each patient's outcome randomly sampled (10% control event
probability, and a 30% effect size for treatment). Analysis shows no asymmetry
(p > 0.05). In plot B, we add a single typical variation in COVID-19 treatment
trials — treatment delay. Consider that efficacy varies from 90% for
treatment within 24 hours, reducing to 10% when treatment is delayed 3 days.
In plot B, each trial's treatment delay is randomly selected. Analysis now
shows highly significant asymmetry, p < 0.0001, with six variants of
Egger's test all showing p < 0.0573-80.
Note that these tests fail even though treatment delay is uniformly
distributed. In reality treatment delay is more complex — each trial has
a different distribution of delays across patients, and the distribution
across trials may be biased (e.g., late treatment trials may be more common).
Similarly, many other variations in trials may produce asymmetry, including
dose, administration, duration of treatment, differences in SOC,
comorbidities, age, variants, and bias in design, implementation, analysis,
and reporting.
Figure 23. Example funnel plot analysis for simulated perfect trials.
Summary statistics from
meta analysis necessarily lose information. As with all meta analyses, studies
are heterogeneous, with differences
in treatment delay, treatment regimen, patient demographics, variants,
conflicts of interest, standard of care, and other factors. We provide analyses for specific
outcomes and by treatment delay, and we aim to identify key characteristics in
the forest plots and summaries. Results should be viewed in the context of
study characteristics.
Some analyses classify treatment based on early or late
administration, as done here, while others distinguish between mild, moderate,
and severe cases. Viral load does not indicate degree of symptoms — for
example patients may have a high viral load while being asymptomatic. With
regard to treatments that have antiviral properties, timing of treatment is
critical — late administration may be less helpful regardless of
severity.
Details of treatment delay per patient is often not available.
For example, a study may treat 90% of patients relatively early, but the
events driving the outcome may come from 10% of patients treated very late.
Our 5 day cutoff for early treatment may be too conservative, 5 days may be too late in many cases.
Comparison across treatments is confounded by differences in
the studies performed, for example dose, variants, and conflicts of interest.
Trials with conflicts of interest may use designs better suited to the
preferred outcome.
In some cases, the most serious outcome has very few events,
resulting in lower confidence results being used in pooled analysis, however
the method is simpler and more transparent. This is less critical as the
number of studies increases. Restriction to outcomes with sufficient power may
be beneficial in pooled analysis and improve accuracy when there are few
studies, however we maintain our pre-specified method to avoid any
retrospective changes.
Studies show that combinations of treatments can be highly
synergistic and may result in many times greater efficacy than individual
treatments alone60-71.
Therefore standard of care may be critical and benefits may diminish or
disappear if standard of care does not include certain treatments.
This real-time analysis is constantly updated based on
submissions. Accuracy benefits from widespread review and submission of
updates and corrections from reviewers. Less popular treatments may receive
fewer reviews.
No treatment or intervention is 100% available and
effective for all current and future variants. Efficacy may vary significantly
with different variants and within different populations. All treatments have
potential side effects. Propensity to experience side effects may be predicted
in advance by qualified physicians. We do not provide medical advice. Before
taking any medication, consult a qualified physician who can compare all
options, provide personalized advice, and provide details of risks and
benefits based on individual medical history and situations.
Focosi (C) et al. present a review covering regdanvimab for COVID-19.
SARS-CoV-2 infection and replication involves a complex
interplay of 50+ host and viral proteins and other
factors24-30, providing many therapeutic
targets.
Over 8,000 compounds have been predicted to reduce COVID-19
risk31, either by directly
minimizing infection or replication, by supporting immune system function, or
by minimizing secondary complications.
Figure 24 shows an overview of the results for regdanvimab
in the context of multiple COVID-19 treatments, and Figure 25 shows a plot
of efficacy vs. cost for COVID-19 treatments.
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Figure 24.
Scatter plot showing results within the context of multiple COVID-19 treatments.
Diamonds shows the results of random effects meta-analysis.
0.5% of 8,000+ proposed treatments show efficacy82.
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Figure 25. Efficacy vs. cost for COVID-19 treatments.
Studies to date show that regdanvimab is
an effective treatment for COVID-19.
Significantly lower risk is seen for mortality, hospitalization, progression, and recovery. 10 studies from 7 independent teams (all from the same country) show significant
benefit.
Meta analysis using the most serious outcome reported shows
63% [51‑71%] lower risk. Results are similar for higher quality studies and worse for Randomized Controlled Trials.
Results are very robust — in exclusion sensitivity analysis 9 of
11 studies must be excluded to avoid finding statistically significant
efficacy in pooled analysis.
Efficacy is variant dependent. In Vitro research suggests a lack of efficacy for omicron BA.2, BA.4, BA.51, ХВВ.1.9.1, XBB.1.9.3, XBB.1.5.24, XBB.1.16, XBB.2.9, BQ.1.1.45, CL.1, and CH.1.12. mAb use may create new variants that spread globally3,4, and may be associated with prolonged viral loads, clinical deterioration, and immune escape4-7.
Retrospective 124 hospitalized severe COVID-19 patients receiving oxygen and remdesivir treatment in South Korea. A subgroup of 25 patients also received the monoclonal antibody regdanvimab prior to remdesivir. The regdanvimab subgroup had significantly more oxygen-free days (primary outcome), higher oxygen saturation, less advanced respiratory support, and shorter oxygen supplementation duration compared to the remdesivir alone group.
Retrospective 398 hospitalized mild-to-moderate COVID-19 patients in South Korea eligible for regdanvimab treatment. 65 patients received regdanvimab, with significantly lower supplemental oxygen requirements (6.2% vs 20.1% in controls). After adjusting for potential confounders, regdanvimab remained associated with lower risk of requiring supplemental oxygen (OR 0.20). There was no significant difference in mortality or hospitalization time in unadjusted results.
PSM retrospective 378 hospitalized COVID-19 patients in Korea showing lower progression with regdanvimab treatment.
Retrospective 722 hospitalized mild-to-moderate COVID-19 patients in Korea showing lower risk of disease progression with regdanvimab treatment.
Retrospective 317 hospitalized mild-moderate COVID-19 patients in South Korea showing significantly lower rates of oxygen desaturation (SpO2 <94%) at 28 days (primary outcome) with regdanvimab monoclonal antibody treatment (13%) compared to standard of care (40%). Regdanvimab also showed benefits in time to fever recovery, discharge rates, and supplemental oxygen use.
Retrospective 2,214 mild/moderate COVID-19 patients in South Korea, 1,095 treated with regdanivimab, showing lower oxygen requirements and lower progression to severe disease with treatment in the overall cohort, but not within the delta subset.
RCT 1,315 outpatients in South Korea, showing lower progression and improved recovery with regdanvimab.
Retrospective 230 hemodialysis patients with COVID-19, showing lower mortality with regdanvimab. Details of the adjusted results are not provided.
Retrospective 778 mild COVID-19 patients showing significantly lower progression to severe disease with regdanvimab treatment.
Confounding by treatment propensity. This study analyzes a population where only a fraction of eligible patients received the treatment. Patients receiving treatment may be more likely to follow other recommendations, more likely to receive additional care, and more likely to use additional treatments that are not tracked in the data (e.g., nasal/oral hygiene83,84, vitamin D85, etc.) — either because the physician recommending regdanvimab also recommended them, or because the patient seeking out regdanvimab is more likely to be familiar with the efficacy of additional treatments and more likely to take the time to use them. Therefore, these kind of studies may overestimate the efficacy of treatments.
Confounding by treatment propensity. This study analyzes a population where only a fraction of eligible patients received the treatment. Patients receiving treatment may be more likely to follow other recommendations, more likely to receive additional care, and more likely to use additional treatments that are not tracked in the data (e.g., nasal/oral hygiene83,84, vitamin D85, etc.) — either because the physician recommending regdanvimab also recommended them, or because the patient seeking out regdanvimab is more likely to be familiar with the efficacy of additional treatments and more likely to take the time to use them. Therefore, these kind of studies may overestimate the efficacy of treatments.
Retrospective propensity score matched analysis of 970 high-risk mild-moderate COVID-19 patients in South Korea, showing regdanvimab significantly reduced risk of disease progression or death by 77% compared to standard care alone. No deaths occurred in either group. Regdanvimab also significantly shortened hospital stay and reduced hematological adverse events.
Confounding by treatment propensity. This study analyzes a population where only a fraction of eligible patients received the treatment. Patients receiving treatment may be more likely to follow other recommendations, more likely to receive additional care, and more likely to use additional treatments that are not tracked in the data (e.g., nasal/oral hygiene83,84, vitamin D85, etc.) — either because the physician recommending regdanvimab also recommended them, or because the patient seeking out regdanvimab is more likely to be familiar with the efficacy of additional treatments and more likely to take the time to use them. Therefore, these kind of studies may overestimate the efficacy of treatments.
Confounding by treatment propensity. This study analyzes a population where only a fraction of eligible patients received the treatment. Patients receiving treatment may be more likely to follow other recommendations, more likely to receive additional care, and more likely to use additional treatments that are not tracked in the data (e.g., nasal/oral hygiene83,84, vitamin D85, etc.) — either because the physician recommending regdanvimab also recommended them, or because the patient seeking out regdanvimab is more likely to be familiar with the efficacy of additional treatments and more likely to take the time to use them. Therefore, these kind of studies may overestimate the efficacy of treatments.
Phase 2 RCT with 307 outpatients with mild-moderate COVID-19, showing regdanvimab (monoclonal antibody) resulted in a minor decrease in time to negative PCR test (primary endpoint) compared to placebo, which was not statistically significant. Regdanvimab did significantly reduce time to clinical recovery by 3 days compared to placebo. A composite outcome of requiring hospitalization or oxygen therapy occurred in 4.4% of regdanvimab patients versus 8.7% placebo, with greater differences in moderate disease patients (7.2% vs 15.8% placebo). No safety issues were identified.
We perform ongoing searches of PubMed, medRxiv, Europe PMC,
ClinicalTrials.gov, The Cochrane Library, Google Scholar, Research
Square, ScienceDirect, Oxford University Press, the reference lists of other
studies and meta-analyses, and submissions to the site c19early.org.
Search terms are regdanvimab and COVID-19 or SARS-CoV-2. Automated searches are performed twice daily, with all matches reviewed for inclusion.
All studies regarding the use of regdanvimab for COVID-19 that report
a comparison with a control group are included in the main analysis.
Sensitivity analysis is performed, excluding studies with major issues,
epidemiological studies, and studies with minimal available information.
This is a living analysis and is updated regularly.
We extracted effect sizes and associated data from all studies.
If studies report multiple kinds of effects then the most serious
outcome is used in pooled analysis, while other outcomes are included in the
outcome specific analyses. For example, if effects for mortality and cases are
both reported, the effect for mortality is used, this may be different to the
effect that a study focused on.
If symptomatic
results are reported at multiple times, we used the latest time, for example
if mortality results are provided at 14 days and 28 days, the results at 28
days have preference. Mortality alone is preferred over combined outcomes.
Outcomes with zero events in both arms are not used, the next most serious
outcome with one or more events is used. For example, in low-risk populations
with no mortality, a reduction in mortality with treatment is not possible,
however a reduction in hospitalization, for example, is still valuable.
Clinical outcomes are considered more important than viral test status. When
basically all patients recover in both treatment and control groups,
preference for viral clearance and recovery is given to results mid-recovery
where available. After most or all patients have recovered there is little or
no room for an effective treatment to do better, however faster recovery is
valuable.
If only individual symptom data is available, the most serious symptom has
priority, for example difficulty breathing or low SpO2 is more
important than cough.
When results provide an odds ratio, we compute the relative risk when
possible, or convert to a relative risk according to86.
Reported confidence intervals and p-values were used when available,
using adjusted values when provided. If multiple types of adjustments are
reported propensity score matching and multivariable regression has preference
over propensity score matching or weighting, which has preference over
multivariable regression. Adjusted results have preference over unadjusted
results for a more serious outcome when the adjustments significantly alter
results. When needed, conversion between reported p-values and
confidence intervals followed Altman, Altman (B), and Fisher's exact
test was used to calculate p-values for event data. If continuity
correction for zero values is required, we use the reciprocal of the opposite
arm with the sum of the correction factors equal to 189.
Results are expressed with RR < 1.0 favoring treatment, and using the risk of
a negative outcome when applicable (for example, the risk of death rather than
the risk of survival). If studies only report relative continuous values such
as relative times, the ratio of the time for the treatment group versus the
time for the control group is used. Calculations are done in Python
(3.13.1) with
scipy (1.14.1), pythonmeta (1.26), numpy (1.26.4), statsmodels (0.14.4), and plotly (5.24.1).
Forest plots are computed using PythonMeta90
with the DerSimonian and Laird random effects model (the fixed effect
assumption is not plausible in this case) and inverse variance weighting.
Results are presented with 95% confidence intervals. Heterogeneity among studies was
assessed using the I2 statistic.
Mixed-effects meta-regression results are computed with R (4.4.0) using the metafor
(4.6-0) and rms (6.8-0) packages, and using the most serious sufficiently powered outcome.
For all statistical tests, a p-value less than 0.05 was considered statistically significant.
Grobid 0.8.0 is used to parse PDF documents.
We have classified studies as early treatment if most patients
are not already at a severe stage at the time of treatment (for example based
on oxygen status or lung involvement), and treatment started within 5 days of
the onset of symptoms. If studies contain a mix of early treatment and late
treatment patients, we consider the treatment time of patients contributing
most to the events (for example, consider a study where most patients are
treated early but late treatment patients are included, and all mortality
events were observed with late treatment patients).
We note that a shorter time may be preferable. Antivirals are typically only
considered effective when used within a shorter timeframe, for example 0-36 or
0-48 hours for oseltamivir, with longer delays not being effective45,46.
We received no funding, this research is done in our spare
time. We have no affiliations with any pharmaceutical companies or political
parties.
A summary of study results is below. Please submit
updates and corrections at https://c19early.org/rgmeta.html.
Effect extraction follows pre-specified rules as detailed above
and gives priority to more serious outcomes.
For pooled analyses, the first (most serious) outcome is used, which may
differ from the effect a paper focuses on.
Other outcomes are used in outcome specific analyses.
| Chae, 3/18/2022, retrospective, South Korea, peer-reviewed, mean age 57.6, 14 authors, study period 1 March, 2021 - 11 May, 2021, average treatment delay 3.68 days. | risk of death, 71.5% lower, RR 0.29, p = 1.00, treatment 0 of 25 (0.0%), control 2 of 99 (2.0%), NNT 49, relative risk is not 0 because of continuity correction due to zero events (with reciprocal of the contrasting arm). |
| risk of mechanical ventilation, 64.0% lower, RR 0.36, p = 0.46, treatment 1 of 25 (4.0%), control 11 of 99 (11.1%), NNT 14. | |
| hospitalization time, 8.6% lower, relative time 0.91, p = 0.56, treatment mean 14.32 (±6.78) n=25, control mean 15.67 (±11.12) n=99. | |
| Hwang, 4/12/2024, retrospective, South Korea, peer-reviewed, 13 authors, study period 26 May, 2021 - 30 January, 2022. | risk of death, 83.3% lower, RR 0.17, p = 0.12, treatment 1 of 189 (0.5%), control 6 of 189 (3.2%), NNT 38. |
| risk of death, 92.3% lower, RR 0.08, p = 0.03, treatment 0 of 189 (0.0%), control 6 of 189 (3.2%), NNT 32, relative risk is not 0 because of continuity correction due to zero events (with reciprocal of the contrasting arm), day 30. | |
| risk of mechanical ventilation, no change, RR 1.00, p = 1.00, treatment 1 of 189 (0.5%), control 1 of 189 (0.5%). | |
| risk of ICU admission, 33.3% lower, RR 0.67, p = 0.49, treatment 8 of 189 (4.2%), control 12 of 189 (6.3%), NNT 47. | |
| risk of oxygen therapy, 54.8% lower, RR 0.45, p = 0.01, treatment 14 of 189 (7.4%), control 31 of 189 (16.4%), NNT 11. | |
| Jang, 1/6/2023, retrospective, South Korea, peer-reviewed, 3 authors, study period September 2020 - October 2021. | risk of death, 70.4% lower, RR 0.30, p = 0.42, treatment 0 of 418 (0.0%), control 1 of 304 (0.3%), NNT 304, relative risk is not 0 because of continuity correction due to zero events (with reciprocal of the contrasting arm). |
| hospitalization time, 12.1% lower, relative time 0.88, p < 0.001, treatment mean 10.27 (±2.94) n=418, control mean 11.69 (±4.71) n=304. | |
| risk of oxygen therapy, 48.5% lower, RR 0.51, p < 0.001, treatment 92 of 418 (22.0%), control 130 of 304 (42.8%), NNT 4.8. | |
| risk of no hospital discharge, 67.8% lower, RR 0.32, p < 0.001, treatment 31 of 418 (7.4%), control 70 of 304 (23.0%), NNT 6.4. | |
| Jang (B), 5/16/2022, retrospective, South Korea, peer-reviewed, 3 authors, study period September 2020 - July 2021. | risk of oxygen therapy, 59.6% lower, RR 0.40, p < 0.001, treatment 17 of 73 (23.3%), control 79 of 137 (57.7%), NNT 2.9. |
| risk of no hospital discharge, 44.1% lower, RR 0.56, p = 0.03, treatment 14 of 73 (19.2%), control 47 of 137 (34.3%), NNT 6.6, day 14. | |
| risk of no hospital discharge, 34.9% lower, RR 0.65, p < 0.001, treatment 34 of 73 (46.6%), control 98 of 137 (71.5%), NNT 4.0, day 11. | |
| hospitalization time, 12.9% lower, relative time 0.87, p = 0.003, treatment mean 12.1 (±4.0) n=73, control mean 13.9 (±4.3) n=137. | |
| Kim, 5/15/2023, retrospective, South Korea, peer-reviewed, 20 authors, study period December 2020 - September 2021, average treatment delay 3.6 days. | risk of progression, 51.1% lower, HR 0.49, p < 0.001, treatment 1,095, control 1,119, adjusted per study, all, multivariable. |
| risk of progression, 33.5% lower, HR 0.67, p = 0.22, treatment 1,095, control 1,119, adjusted per study, delta, multivariable. | |
| risk of oxygen therapy, 32.3% lower, HR 0.68, p < 0.001, treatment 1,095, control 1,119, adjusted per study, all, multivariable. | |
| risk of oxygen therapy, 3.7% lower, HR 0.96, p = 0.83, treatment 1,095, control 1,119, adjusted per study, delta, multivariable. | |
| Kim (B), 8/8/2022, Double Blind Randomized Controlled Trial, placebo-controlled, multiple countries, peer-reviewed, median age 48.0, 24 authors, study period 18 January, 2021 - 24 April, 2021, average treatment delay 4.0 days, trial NCT04602000 (history). | risk of death, 49.8% lower, RR 0.50, p = 1.00, treatment 1 of 656 (0.2%), control 2 of 659 (0.3%), NNT 662. |
| risk of mechanical ventilation, 85.7% lower, RR 0.14, p = 0.25, treatment 0 of 656 (0.0%), control 3 of 659 (0.5%), NNT 220, relative risk is not 0 because of continuity correction due to zero events (with reciprocal of the contrasting arm). | |
| risk of ICU admission, 90.9% lower, RR 0.09, p = 0.06, treatment 0 of 656 (0.0%), control 5 of 659 (0.8%), NNT 132, relative risk is not 0 because of continuity correction due to zero events (with reciprocal of the contrasting arm). | |
| risk of oxygen therapy, 69.2% lower, RR 0.31, p < 0.001, treatment 15 of 656 (2.3%), control 49 of 659 (7.4%), NNT 19. | |
| risk of hospitalization, 69.1% lower, RR 0.31, p < 0.001, treatment 16 of 656 (2.4%), control 52 of 659 (7.9%), NNT 18. | |
| risk of progression, 69.7% lower, RR 0.30, p < 0.001, treatment 16 of 656 (2.4%), control 53 of 659 (8.0%), NNT 18. | |
| risk of progression, 71.6% lower, RR 0.28, p < 0.001, treatment 14 of 446 (3.1%), control 48 of 434 (11.1%), NNT 13, high-risk patients. | |
| risk of no viral clearance, 32.4% lower, RR 0.68, p < 0.001, treatment 612, control 618, inverted to make RR<1 favor treatment. | |
| Lee (B), 5/23/2024, retrospective, South Korea, peer-reviewed, 6 authors, study period 1 December, 2020 - 30 November, 2021, excluded in exclusion analyses: minimal details provided. | risk of death, 59.4% lower, RR 0.41, p = 0.002, treatment 10 of 77 (13.0%), control 49 of 153 (32.0%), NNT 5.3, unadjusted. |
| Lee (C), 11/23/2021, retrospective, South Korea, peer-reviewed, 10 authors, study period 26 November, 2020 - 28 February, 2021. | risk of death, 58.9% lower, RR 0.41, p = 1.00, treatment 0 of 234 (0.0%), control 1 of 544 (0.2%), NNT 544, relative risk is not 0 because of continuity correction due to zero events (with reciprocal of the contrasting arm). |
| risk of severe case, 82.4% lower, HR 0.18, p = 0.002, treatment 234, control 234, adjusted per study, propensity score matching, multivariable. | |
| risk of oxygen therapy, 45.2% lower, HR 0.55, p = 0.05, treatment 234, control 234, adjusted per study, propensity score matching, multivariable. | |
| time to discharge, 8.3% lower, relative time 0.92, p = 0.001, treatment 234, control 544. | |
| risk of no hospital discharge, 76.8% lower, RR 0.23, p < 0.001, treatment 5 of 234 (2.1%), control 50 of 544 (9.2%), NNT 14. | |
| Park, 3/29/2022, retrospective, South Korea, peer-reviewed, 5 authors, study period 1 December, 2020 - 16 April, 2021. | risk of progression, 79.4% lower, RR 0.21, p < 0.001, treatment 19 of 377 (5.0%), control 81 of 377 (21.5%), NNT 6.1, adjusted per study, odds ratio converted to relative risk, disease aggravation or death, propensity score matching, multivariable. |
| hospitalization time, 13.1% lower, relative time 0.87, p < 0.001, treatment mean 11.9 (±3.3) n=377, control mean 13.7 (±5.4) n=377, propensity score matching. | |
| Streinu-Cercel, 2/2/2022, Double Blind Randomized Controlled Trial, placebo-controlled, multiple countries, peer-reviewed, 17 authors, average treatment delay 3.0 days, trial NCT04602000 (history). | risk of mechanical ventilation, 151.2% higher, RR 2.51, p = 1.00, treatment 1 of 203 (0.5%), control 0 of 104 (0.0%), continuity correction due to zero event (with reciprocal of the contrasting arm). |
| risk of oxygen therapy, 54.5% lower, RR 0.46, p = 0.11, treatment 8 of 203 (3.9%), control 9 of 104 (8.7%), NNT 21. | |
| risk of hospitalization, 48.8% lower, RR 0.51, p = 0.20, treatment 9 of 203 (4.4%), control 9 of 104 (8.7%), NNT 24. | |
| composite outcome, 48.8% lower, RR 0.51, p = 0.20, treatment 9 of 203 (4.4%), control 9 of 104 (8.7%), NNT 24. | |
| recovery time, 35.2% lower, relative time 0.65, p = 0.003, treatment mean 5.7 (±5.82) n=203, control mean 8.8 (±12.5) n=104. | |
| time to viral-, 1.6% lower, relative time 0.98, p = 0.88, treatment mean 12.7 (±13.8) n=203, control mean 12.9 (±3.12) n=104. |
Effect extraction follows pre-specified rules as detailed above
and gives priority to more serious outcomes.
For pooled analyses, the first (most serious) outcome is used, which may
differ from the effect a paper focuses on.
Other outcomes are used in outcome specific analyses.
| Choi, 3/8/2022, retrospective, South Korea, peer-reviewed, 3 authors. | risk of death, 85.7% lower, RR 0.14, p = 1.00, treatment 0 of 65 (0.0%), control 5 of 333 (1.5%), NNT 67, relative risk is not 0 because of continuity correction due to zero events (with reciprocal of the contrasting arm). |
| risk of oxygen therapy, 76.2% lower, RR 0.24, p = 0.004, treatment 4 of 65 (6.2%), control 67 of 333 (20.1%), NNT 7.2, odds ratio converted to relative risk. |
Viral infection and replication involves attachment, entry, uncoating and release, genome replication and transcription, translation and protein processing, assembly and budding, and release. Each step can be disrupted by therapeutics.
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