Virologic Outcomes with Molnupiravir in Non-hospitalized Adult Patients with COVID-19 from the Randomized, Placebo-Controlled MOVe-OUT Trial

Impact of differences between interim and post-interim analysis populations on outcomes of a group sequential trial: Example of the MOVe-OUT study

BackgroundPre-specified interim analyses allow for more timely evaluation of efficacy or futility, potentially accelerating decision-making on an investigational intervention. In such an analysis, the randomized, double-blind MOVe-OUT trial demonstrated superiority of molnupiravir over placebo for outpatient treatment of COVID-19 in high-risk patients. In the full analysis population, the point estimate of the treatment difference in the primary endpoint was notably lower than at the interim analysis. We conducted a comprehensive assessment to investigate this unexpected difference in treatment effect size, with the goal of informing future clinical research evaluating treatments for rapidly evolving infectious diseases.MethodsThe modified intention-to-treat population of the MOVe-OUT trial was divided into an interim analysis cohort (i.e. all participants included in the interim analysis; prospectively defined) and a post-interim analysis cohort (i.e. all remaining participants; retrospectively defined). Baseline characteristics (including many well-established prognostic factors for disease progression), clinical outcomes, and virologic outcomes were retrospectively evaluated. The impact of changes in baseline characteristics over time was explored using logistic regression modeling and simulations.ResultsBaseline characteristics were well-balanced between arms overall. However, between- and within-arm differences in known prognostic baseline factors (e.g. comorbidities, SARS-CoV-2 viral load, and anti-SARS-CoV-2 antibody status) were observed for the interim and post-interim analysis cohorts. For the individual factors, these differences were generally minor and otherwise not notable; as the trial progressed, however, these shifts in combination increasingly favored the placebo arm across most of the evaluated factors in the post-interim cohort. Model-based simulations confirmed that the reduction in effect size could be accounted for by these longitudinal trends toward a lower-risk study population among placebo participants. Infectivity and viral load data confirmed that molnupiravir's antiviral activity was consistent across both cohorts, which were heavily dominated by different viral clades (reflecting the rapid SARS-CoV-2 evolution).DiscussionThe cumulative effect of randomly occurring minor differences in prognostic baseline characteristics within and between arms over time, rather than virologic factors such as reduced activity of molnupiravir against evolving variants, likely impacted the observed outcomes. Our results have broader implications for group sequential trials seeking to evaluate treatments for rapidly emerging pathogens. During dynamic epidemic or pandemic conditions, adaptive trials should be designed and interpreted especially carefully, considering that they will likely rapidly enroll a large post-interim overrun population and that even small longitudinal shifts across multiple baseline variables can disproportionately impact prespecified efficacy outcomes at different timepoints. Shifts in prognostic factors may introduce additional variability that can be difficult to disentangle from temporal trends in epidemiology (e.g. evolutionary changes in the causative pathogen) or disease management.(ClinicalTrials.gov: NCT04575597.).

Drug treatments for mild or moderate covid-19: systematic review and network meta-analysis

OBJECTIVE

To compare the effects of treatments for mild or moderate (that is, non-severe) coronavirus disease 2019 (covid-19).

DESIGN

Systematic review and network meta-analysis.

DATA SOURCES

Covid-19 Living Overview of Evidence Repository (covid-19 L-OVE) by the Epistemonikos Foundation, a public, living repository of covid-19 articles, from 1 January 2023 to 19 May 2024. The search also included the WHO covid-19 database (up to 17 February 2023) and six Chinese databases (up to 20 February 2021). The analysis included studies identified between 1 December 2019 and 28 June 2023.

STUDY SELECTION

Randomised clinical trials in which people with suspected, probable, or confirmed mild or moderate covid-19 were allocated to drug treatment or to standard care or placebo. Pairs of reviewers independently screened potentially eligible articles.

METHODS

After duplicate data abstraction, a bayesian network meta-analysis was conducted. Risk of bias was assessed by use of a modification of the Cochrane risk of bias 2.0 tool, and the certainty of the evidence using the grading of recommendations assessment, development, and evaluation (GRADE) approach. For each outcome, following GRADE guidance, drug treatments were classified in groups from the most to the least beneficial or harmful.

RESULTS

Of 259 trials enrolling 166 230 patients, 187 (72%) were included in the analysis. Compared with standard care, two drugs probably reduce hospital admission: nirmatrelvir-ritonavir (25 fewer per 1000 (95% confidence interval 28 fewer to 20 fewer), moderate certainty) and remdesivir (21 fewer per 1000 (28 fewer to 7 fewer), moderate certainty). Molnupiravir and systemic corticosteroids may reduce hospital admission (low certainty). Compared with standard care, azithromycin probably reduces time to symptom resolution (mean difference 4 days fewer (5 fewer to 3 fewer), moderate certainty) and systemic corticosteroids, favipiravir, molnupiravir, and umifenovir probably also reduce duration of symptoms (moderate to high certainty). Compared with standard care, only lopinavir-ritonavir increased adverse effects leading to discontinuation.

CONCLUSION

Nirmatrelvir-ritonavir and remdesivir probably reduce admission to hospital, and systemic corticosteroids and molnupiravir may reduce admission to hospital. Several medications including systemic corticosteroids and molnupiravir probably reduce time to symptom resolution.

SYSTEMATIC REVIEW REGISTRATION

This review was not registered. The protocol is publicly available in the supplementary material.

Comparison of Molnupiravir Exposure-Response Relationships for Virology Response and Mechanism of Action Biomarkers With Clinical Outcomes in Treatment of COVID-19

Molnupiravir, an orally administered drug for the treatment of mild-to-moderate COVID-19, is a prodrug of the ribonucleoside β-D-N4-hydroxycytidine (NHC). NHC incorporation in the SARS-CoV-2 RNA strand causes an accumulation of deleterious errors in the genome, resulting in reduced viral infectivity and replication. Exposure-response (E-R) analyses for viral RNA mutation rate and virologic outcomes were conducted using data from three phase 2/3 studies of molnupiravir (P006, MOVe-IN, and MOVe-OUT). Three dose levels (200, 400, and 800 mg every 12 hours [Q12H]) and placebo were evaluated. E-R datasets were generated for SARS-CoV-2 RNA mutation and longitudinal SARS-CoV-2 RNA viral load. E-R models were defined for RNA mutation rate and viral load change from baseline at days 5 and 10. The models supported plasma NHC AUC0-12 as the appropriate pharmacokinetic driver for assessing E-R relationships. The highest percentage of participants with > 20 low-frequency nucleotide substitutions (LNS) per 10,000 bases, a measure of likely meaningful drug effect, was predicted in the 800 mg Q12H treatment group. A strong drug effect on the reduction of viral load was observed on days 5 and 10. E-R relationships were best represented by an Emax structural model with reasonable consistency in the estimated AUC50s (~2.3-fold), across the models, of 10,260 and 4390 nM*hr. for day 5 viral load change from baseline and LNS error rate, respectively. These biomarker E-R curves support the choice of 800 mg Q12H as providing near-maximal drug effect, consistent with findings from the previously published molnupiravir E-R model of clinical outcomes.

Assessment of pharmacokinetics and tolerability following single-dose administration of molnupiravir in participants with hepatic or renal impairment

Individuals with chronic liver or kidney disease are at increased risk of severe COVID-19. Molnupiravir is an orally administered antiviral authorized for the treatment of mild-to-moderate COVID-19 in adults at risk of progression to severe disease. Two nonrandomized, open-label, single-dose, multicenter, phase 1 trials were conducted to investigate the effects of hepatic and renal impairment on the tolerability and pharmacokinetics of molnupiravir (800 mg) and its metabolite β-D-N4-hydroxycytidine (NHC; NCT05386589/NCT05386758). The impact of renal impairment on urinary excretion of NHC was also assessed. The 90% CI for the geometric mean ratio of the plasma NHC area under the concentration-time curve (AUC) from zero to infinity was <2.0 for participants with moderate hepatic or severe renal impairment versus healthy mean-matched controls. Comparable geometric mean values were observed for other pharmacokinetic parameters-including AUC from 0 to 12 h, AUC from zero to the last measurable concentration, and peak plasma concentration-in participants with moderate hepatic or severe renal impairment and in healthy mean-matched controls. Urinary excretion of NHC was low in healthy participants and participants with severe renal impairment; renal clearance was numerically lower in those with renal impairment. In both trials, all adverse events were of mild or moderate intensity and resolved by study completion. There were no clinically relevant treatment-related effects on other safety evaluations. Overall, molnupiravir was generally well-tolerated, with similar pharmacokinetic profiles in participants with hepatic or renal impairment and healthy participants, supporting its use for treating COVID-19 in these individuals without the need for dose adjustment.

Comprehensive genotoxicity and carcinogenicity assessment of molnupiravir

Molnupiravir is registered or authorized in several countries as a 5-d oral coronavirus disease 2019 treatment for adults. Molnupiravir is a prodrug of the antiviral ribonucleoside β-D-N4-hydroxycytidine (NHC) that distributes into cells, where it is phosphorylated to its pharmacologically active ribonucleoside triphosphate (NHC-TP) form. NHC-TP incorporates into severe acute respiratory syndrome coronavirus 2 RNA by the viral RNA-dependent RNA polymerase, resulting in an accumulation of errors in the viral genome, leading to inhibition of viral replication and loss of infectivity. The potential of molnupiravir to induce genomic mutations and DNA damage was comprehensively assessed in several in vitro and in vivo genotoxicity assays and a carcinogenicity study, in accordance with international guideline recommendations and expert opinion. Molnupiravir and NHC induced mutations in vitro in bacteria and mammalian cells but did not induce chromosome damage in in vitro or in vivo assays. The in vivo mutagenic and carcinogenic potential of molnupiravir was tested in a series of in vivo mutagenicity studies in somatic and germ cells (Pig-a Assay and Big Blue® TGR Mutation Assay) and in a carcinogenicity study (transgenic rasH2-Tg mouse), using durations of exposure and doses exceeding those used in clinical therapy. In vitro genotoxicity results are superseded by robustly conducted in vivo studies. Molnupiravir did not increase mutations in somatic or germ cells in the in vivo animal studies and was negative in the carcinogenicity study. The interpretation criteria for each study followed established regulatory guidelines. Taken together, these data indicate that molnupiravir use does not present a genotoxicity or carcinogenicity risk for patients.

Potential of traditional medicines in alleviating COVID-19 symptoms

This review discusses the prevention and treatment of coronavirus disease 2019 (COVID-19) caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Mutations in its spike glycoprotein have driven the emergence of variants with high transmissibility and immune escape capabilities. Some antiviral drugs are ineffective against the BA.2 subvariant at the authorized dose. Recently, 150 natural metabolites have been identified as potential candidates for development of new anti-COVID-19 drugs with higher efficacy and lower toxicity than those of existing therapeutic agents. Botanical drug-derived bioactive molecules have shown promise in dampening the COVID-19 cytokine storm and thus preventing pulmonary fibrosis, as they exert a strong binding affinity for viral proteins and inhibit their activity. The Health Ministry of Thailand has approved Andrographis paniculata (Jap. Senshinren) extracts to treat COVID-19. In China, over 85% of patients infected with SARS-CoV-2 receive treatments based on traditional Chinese medicine. A comprehensive map of the stages and pathogenetic mechanisms related to the disease and effective natural products to treat and prevent COVID-19 are presented. Approximately 10% of patients with COVID-19 are affected by long COVID, and COVID-19 infection impairs mitochondrial DNA. As the number of agents to treat COVID-19 is limited, adjuvant botanical drug treatments including vitamin C and E supplementation may reduce COVID-19 symptoms and inhibit progression to long COVID.

Molnupiravir: Mechanism of action, clinical, and translational science

Molnupiravir is an oral prodrug of the broadly active, antiviral ribonucleoside analog N-hydroxycytidine (NHC). The primary circulating metabolite NHC is taken up into cells and phosphorylated to NHC-triphosphate (NHC-TP). NHC-TP serves as a competitive substrate for viral RNA-dependent RNA polymerase (RdRp), which results in an accumulation of errors in the viral genome, rendering virus replication incompetent. Molnupiravir has demonstrated activity against SARS-CoV-2 both clinically and preclinically and has a high barrier to development of viral resistance. Little to no molnupiravir is observed in plasma due to rapid hydrolysis to NHC. Maximum concentrations of NHC are reached at 1.5 h following administration in a fasted state. The effective half-life of NHC is 3.3 h, reflecting minimal accumulation in the plasma following twice-daily (Q12H) dosing. The terminal half-life of NHC is 20.6 h. NHC-TP exhibits a flatter profile with a lower peak-to-trough ratio compared with NHC, which supports Q12H dosing. Renal and hepatic pathways are not major routes of elimination, as NHC is primarily cleared by metabolism to uridine and cytidine, which then mix with the endogenous nucleotide pools. In a phase III study of nonhospitalized patients with COVID-19 (MOVe-OUT), 5 days of treatment with 800 mg molnupiravir Q12H significantly reduced the incidence of hospitalization or death compared with placebo. Patients treated with molnupiravir also had a greater reduction in SARS-CoV-2 viral load and improved clinical outcomes, compared with those receiving placebo. The clinical effectiveness of molnupiravir has been further demonstrated in several real-world evidence studies. Molnupiravir is currently authorized or approved in more than 25 countries.