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.

The unprecedented magnitude of the 2013-2016 Ebola virus (EBOV) epidemic in West Africa resulted in over 11 000 deaths and spurred an international public health emergency. A second outbreak in 2018-2020 in DRC resulted in an additional >3400 cases and nearly 2300 deaths (WHO, 2020). These large outbreaks across geographically diverse regions highlight the need for the development of effective oral therapeutic agents that can be easily distributed for self-administration to populations with active disease or at risk of infection. Herein, we report the in vivo efficacy of N4-hydroxycytidine (EIDD-1931), a broadly active ribonucleoside analog and the active metabolite of the prodrug EIDD-2801 (molnupiravir), in murine models of lethal EBOV infection. Twice daily oral dosing with EIDD-1931 at 200 mg/kg for 7 days, initiated either with a prophylactic dose 2 h before infection, or as therapeutic treatment starting 6 h post-infection, resulted in 92-100% survival of mice challenged with lethal doses of EBOV, reduced clinical signs of Ebola virus disease (EVD), reduced serum virus titers, and facilitated weight loss recovery. These results support further investigation of molnupiravir as a potential therapeutic or prophylactic treatment for EVD.

Effective antiviral treatments for coronavirus disease 2019 (COVID-19) are needed to reduce the morbidity and mortality associated with severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection, particularly in patients with risk factors for severe disease. Molnupiravir (MK-4482, EIDD-2801) is an orally administered, ribonucleoside prodrug of β-D-N4-hydroxycytidine (NHC) with submicromolar potency against SARS-CoV-2. A population pharmacokinetic (PopPK) analysis for molnupiravir exposure was conducted using 4202 NHC plasma concentrations collected in 1207 individuals from a phase I trial in healthy participants, a phase IIa trial in non-hospitalized participants with COVID-19, a phase II trial in hospitalized participants with COVID-19, and a phase II/III trial in non-hospitalized participants with COVID-19. Molnupiravir pharmacokinetics (PK) was best described by a two-compartment model with a transit-compartment absorption model and linear elimination. Molnupiravir apparent elimination clearance increased with body weight less-than-proportionally (power 0.412) and was estimated as 70.6 L/h in 80-kg individuals with a moderate interindividual variability (43.4% coefficient of variation). Additionally, effects of sex and body mass index on apparent central volume and food status and formulation on the absorption mean transit time were identified as statistically significant descriptors of variability in these PK parameters. However, none of the identified covariate effects caused clinically relevant changes in the area under the NHC concentration versus time curve between doses, the exposure metric most closely related to clinical response. Overall, the PopPK model indicates that molnupiravir can be administered in adults without dose adjustment based on age, sex, body size, food, and mild-to-moderate renal or mild hepatic impairment.

Background The antiviral drug molnupiravir was licensed for treating at-risk patients with COVID-19 on the basis of data from unvaccinated adults. We aimed to evaluate the safety and virological efficacy of molnupiravir in vaccinated and unvaccinated individuals with COVID-19.Methods This randomised, placebo-controlled, double-blind, phase 2 trial (AGILE CST-2) was done at five National Institute for Health and Care Research sites in the UK. Eligible participants were adult (aged & GE;18 years) outpatients with PCR-confirmed, mild-to-moderate SARS-CoV-2 infection who were within 5 days of symptom onset. Using permuted blocks (block size 2 or 4) and stratifying by site, participants were randomly assigned (1:1) to receive either molnupiravir (orally; 800 mg twice daily for 5 days) plus standard of care or matching placebo plus standard of care. The primary outcome was the time from randomisation to SARS-CoV-2 PCR negativity on nasopharyngeal swabs and was analysed by use of a Bayesian Cox proportional hazards model for estimating the probability of a superior virological response (hazard ratio [HR]>1) for molnupiravir versus placebo. Our primary model used a two-point prior based on equal prior probabilities (50%) that the HR was 1 & BULL;0 or 1 & BULL;5. We defined a priori that if the probability of a HR of more than 1 was more than 80% molnupiravir would be recommended for further testing. The primary outcome was analysed in the intention-to-treat population and safety was analysed in the safety population, comprising participants who had received at least one dose of allocated treatment. This trial is registered in ClinicalTrials.gov, NCT04746183, and the ISRCTN registry, ISRCTN27106947, and is ongoing.Findings Between Nov 18, 2020, and March 16, 2022, 1723 patients were assessed for eligibility, of whom 180 were randomly assigned to receive either molnupiravir (n=90) or placebo (n=90) and were included in the intention-to-treat analysis. 103 (57%) of 180 participants were female and 77 (43%) were male and 90 (50%) participants had received at least one dose of a COVID-19 vaccine. SARS-CoV-2 infections with the delta (B.1.617.2; 72 [40%] of 180), alpha (B.1.1.7; 37 [21%]), omicron (B.1.1.529; 38 [21%]), and EU1 (B.1.177; 28 [16%]) variants were represented. All 180 participants received at least one dose of treatment and four participants discontinued the study (one in the molnupiravir group and three in the placebo group). Participants in the molnupiravir group had a faster median time from randomisation to negative PCR (8 days [95% CI 8-9]) than participants in the placebo group (11 days [10-11]; HR 1 & BULL;30, 95% credible interval 0 & BULL;92-1 & BULL;71; log-rank p=0 & BULL;074). The probability of molnupiravir being superior to placebo (HR>1) was 75 & BULL;4%, which was less than our threshold of 80%. 73 (81%) of 90 participants in the molnupiravir group and 68 (76%) of 90 participants in the placebo group had at least one adverse event by day 29. One participant in the molnupiravir group and three participants in the placebo group had an adverse event of a Common Terminology Criteria for Adverse Events grade 3 or higher severity. No participants died (due to any cause) during the trial. Interpretation We found molnupiravir to be well tolerated and, although our predefined threshold was not reached, we observed some evidence that molnupiravir has antiviral activity in vaccinated and unvaccinated individuals infected with a broad range of SARS-CoV-2 variants, although this evidence is not conclusive.

SummaryBackgroundMolnupiravir was licensed for treating high-risk patients with COVID-19 based on data from unvaccinated adults. AGILE CST-2 (NCT04746183) Phase II reports safety and virological efficacy of molnupiravir in vaccinated and unvaccinated individuals.MethodsAdult out-patients with PCR-confirmed SARS-CoV-2 infection within five days of symptom onset were randomly assigned 1:1 to receive molnupiravir (800mg twice daily for five days) or placebo. The primary outcome was time to swab PCR-negativity, compared using a Bayesian model for estimating the probability of a superior virological response (Hazard Ratio>1) for molnupiravir over placebo. Secondary outcomes included change in viral titre at day 5, safety and tolerability, clinical progression and patient reported outcome measures. We analysed outcomes after the last participant reached day 29.FindingsOf 180 participants randomised (90 molnupiravir, 90 placebo), 50% were vaccinated. Infections with SARS-CoV-2 variants Delta (40%), Alpha (21%), Omicron (21%) and EU1 (16%) were represented. The median time to negative-PCR was 8 versus 11 days for molnupiravir and placebo (HR=1·30, 95% CrI 0·92-1·71, p=0·07 by Logrank and p=0·03 by Breslow-Gehan tests). Although small numbers precluded subgroup analysis, no obvious differences were observed between vaccinated and unvaccinated participants. Using a two-point prior the probability of molnupiravir being superior to placebo (HR>1) was 75·4%, which was just below our defined threshold of 80% for establishing superiority. Using an uninformative continuous prior, the probability of HR>1 was 94·7%. As an exploratory analysis, the change in viral titre on day 5 (end of treatment) was significantly greater with molnupiravir compared with placebo. A total of 4 participants reported severe adverse events (grade 3+), 3 of whom were in the placebo arm.InterpretationWe found molnupiravir to be well-tolerated, with evidence for high probability of antiviral efficacy in a population of vaccinated and unvaccinated individuals infected with a broad range of viral variants.FundingFunded by Ridgeback Biotherapeutics and UK National Institute for Health and Care Research infrastructure funding. The AGILE platform infrastructure is supported by the Medical Research Council (grant number MR/V028391/1) and the Wellcome Trust (grant number 221590/Z/20/Z).

Abstract ß-d-N4-hydroxycytidine (NHC), the parent nucleoside of molnupiravir, a COVID-19 antiviral, was quantified at SARS-CoV-2 transmission sites in 12 patients enrolled in AGILE Candidate-Specific Trial-2. Saliva, nasal, and tear NHC concentrations were 3%, 21%, and 22% that of plasma. Saliva and nasal NHC were significantly correlated with plasma (P < .0001). Clinical Trials Registration. NCT04746183.

ABSTRACTThe unprecedented magnitude of the 2013-2016 Ebola virus (EBOV) epidemic in West Africa resulted in over 11,000 deaths and spurred an international public health emergency. A second outbreak in 2018-2020 in DRC resulted in an additional >3400 cases and nearly 2300 deaths (WHO Disease Outbreak News: Update 26 June, 2020). These large outbreaks across geographically diverse regions highlight the need for the development of effective oral therapeutic agents that can be easily distributed for self-administration to populations with active disease or at risk of infection. Herein, we report the in vivo efficacy ofN4-hydroxycytidine (EIDD-1931), a broadly active ribonucleoside analog and the active metabolite of the prodrug EIDD-2801 (molnupiravir), in murine models of lethal EBOV infection. Twice daily oral dosing with EIDD-1931 at 200 mg/kg for 7 days, initiated either with a prophylactic dose 2 hours before infection, or as therapeutic treatment starting 6 hours post-infection, resulted in 92-100% survival of mice challenged with lethal doses of EBOV, reduced clinical signs of Ebola virus disease (EVD), reduced serum virus titers, and facilitated weight loss recovery. These results support further investigation of molnupiravir as a potential therapeutic or prophylactic treatment for EVD.

BACKGROUNDAlthough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infectious virus isolation in outpatients with coronavirus disease 2019 (COVID-19) has been associated with viral RNA levels and symptom duration, little is known about the host, disease, and viral determinants of infectious virus detection.METHODSCOVID-19 adult outpatients were enrolled within 7 days of symptom onset. Clinical symptoms were recorded via patient diary. Nasopharyngeal swabs were collected to quantitate SARS-CoV-2 RNA by reverse transcriptase polymerase chain reaction and for infectious virus isolation in Vero E6-cells. SARS-CoV-2 antibodies were measured in serum using a validated ELISA assay.RESULTSAmong 204 participants with mild-to-moderate symptomatic COVID-19, the median nasopharyngeal viral RNA was 6.5 (interquartile range [IQR] 4.7-7.6 log10 copies/mL), and 26% had detectable SARS-CoV-2 antibodies (immunoglobulin (Ig)A, IgM, IgG, and/or total Ig) at baseline. Infectious virus was recovered in 7% of participants with SARS-CoV-2 antibodies compared to 58% of participants without antibodies (prevalence ratio [PR] = 0.12, 95% confidence interval [CI]: .04, .36; P = .00016). Infectious virus isolation was also associated with higher levels of viral RNA (mean RNA difference +2.6 log10, 95% CI: 2.2, 3.0; P < .0001) and fewer days since symptom onset (PR = 0.79, 95% CI: .71, .88 per day; P < .0001).CONCLUSIONSThe presence of SARS-CoV-2 antibodies is strongly associated with clearance of infectious virus. Seropositivity and viral RNA levels are likely more reliable markers of infectious virus clearance than subjective measure of COVID-19 symptom duration. Virus-targeted treatment and prevention strategies should be administered as early as possible and ideally before seroconversion.CLINICAL TRIALS REGISTRATIONNCT04405570.

OBJECTIVES:AGILE is a Phase Ib/IIa platform for rapidly evaluating COVID-19 treatments. In this trial (NCT04746183) we evaluated the safety and optimal dose of molnupiravir in participants with early symptomatic infection. METHODS:We undertook a dose-escalating, open-label, randomized-controlled (standard-of-care) Bayesian adaptive Phase I trial at the Royal Liverpool and Broadgreen Clinical Research Facility. Participants (adult outpatients with PCR-confirmed SARS-CoV-2 infection within 5 days of symptom onset) were randomized 2:1 in groups of 6 participants to 300, 600 and 800 mg doses of molnupiravir orally, twice daily for 5 days or control. A dose was judged unsafe if the probability of 30% or greater dose-limiting toxicity (the primary outcome) over controls was 25% or greater. Secondary outcomes included safety, clinical progression, pharmacokinetics and virological responses. RESULTS:Of 103 participants screened, 18 participants were enrolled between 17 July and 30 October 2020. Molnupiravir was well tolerated at 300, 600 and 800 mg doses with no serious or severe adverse events. Overall, 4 of 4 (100%), 4 of 4 (100%) and 1 of 4 (25%) of the participants receiving 300, 600 and 800 mg molnupiravir, respectively, and 5 of 6 (83%) controls, had at least one adverse event, all of which were mild (≤grade 2). The probability of ≥30% excess toxicity over controls at 800 mg was estimated at 0.9%. CONCLUSIONS:Molnupiravir was safe and well tolerated; a dose of 800 mg twice daily for 5 days was recommended for Phase II evaluation.

Background AGILE is a phase Ib/IIa platform for rapidly evaluating COVID-19 treatments. In this trial ( NCT04746183 ) we evaluated the safety and optimal dose of molnupiravir in participants with early symptomatic infection. Methods We undertook a dose-escalating, open-label, randomised-controlled (standard-of-care) Bayesian adaptive phase I trial at the Royal Liverpool and Broadgreen Clinical Research Facility. Participants (adult outpatients with PCR-confirmed SARS-CoV-2 infection within 5 days of symptom onset) were randomised 2:1 in groups of 6 participants to 300mg, 600mg and 800mg doses of molnupiravir orally, twice daily for 5 days or control. A dose was judged unsafe if the probability of 30% or greater dose-limiting toxicity (the primary outcome) over controls was higher than 25%. Secondary outcomes included safety, clinical progression, pharmacokinetics and virologic responses. Results Of 103 volunteers screened, 18 participants were enrolled between 17 July and 30 October 2020. Molnupiravir was well tolerated at 400, 600 or 800mg doses with no serious or severe adverse events. Overall, 4 of 4 (100%), 4 of 4 (100%) and 1 of 4 (25%) of the participants receiving 300, 600 and 800mg molnupiravir respectively, and 5 of 6 (83%) controls, had at least one adverse event, all of which were mild (≤grade 2). The probability of ≥30% excess toxicity over controls at 800mg was estimated at 0.9%. Conclusion Molnupiravir was safe and well tolerated; a dose of 800mg twice-daily for 5 days was recommended for Phase II evaluation.

A recently published article described the safety, tolerability, and pharmacokinetic profile of molnupiravir (Painter et al. 2021), a novel antiviral agent with potent activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19). Here, we report an unprecedented collaboration between sponsor, contract research organization (CRO), and regulatory authorities that enabled accelerated generation of these phase I data, including administration of the first-in-human (FIH) dose of molnupiravir within 5 days of receiving regulatory approval in the United Kingdom (UK). Single and multiple ascending dose (SAD and MAD, respectively) cohorts were dosed in randomized, double-blind, and placebo-controlled fashion, with a 6:2 active-to-placebo ratio in each cohort. A food-effect (FE) cohort included 10 subjects who were randomized to receive drug in the fasted or fed state followed by the fed or fasted state to complete a fed and fasted sequence for each subject. Dose escalation decisions were accelerated and MAD cohorts were initiated prior to completion of all SAD cohorts with the provision that the total daily dose in a MAD cohort would not exceed a dose proven to be safe and well-tolerated in a SAD cohort. Dosing in healthy volunteers was completed for eight single ascending dose (SAD) cohorts, seven multiple ascending dose (MAD) cohorts, and one food-effect (FE) cohort within approximately 16 weeks of initial protocol submission to the Research Ethics Committee (REC) and Medicines and Healthcare products Regulatory Agency (MHRA). Working to standard industry timelines, the FIH study would have taken approximately 46 weeks to complete and 33 weeks to enable phase 2 dosing. Data from this study supported submission of a phase 2/3 clinical trial protocol to the US Food and Drug Administration (FDA) within 8 weeks of initial protocol submission, with FDA comments permitting phase 2 study initiation within two additional weeks. In the setting of a global pandemic, this model of collaboration allows for accelerated generation of clinical data compared to standard processes, without compromising safety.

Background: The emergence of SARS-CoV-2 viral variants threatens current anti-viral and preventative strategies, including monoclonal antibodies and vaccines. Critically, the limited supply of vaccines and the complex logistics surrounding the delivery of infusion-based therapies herald the need for an easily produced, distributed, and specific direct-acting antiviral for COVID-19 that limits progression of illness and ideally prevents transmission. Methods: The efficacy of molnupiravir was evaluated in a double-blind, randomized, placebo-controlled, Phase 2 dose-range finding study using realtime polymerase chain reaction (RT-PCR) and virus isolation was conducted at 11 study sites in the U.S. Participants were randomized if they had signs or symptoms of COVID-19 within 7 days, and a positive SARS-CoV-2 RT-PCR within 4 days of enrollment. Initially, participants were randomized in a 1:1 ratio to receive 200 mg molnupiravir or placebo twice daily for 5 days. Subsequently, in the dose-range finding portion of the study, participants were randomized in a 3:1 ratio to receive 200, 400, or 800 mg molnupiravir or placebo twice daily for 5 days. Nasopharyngeal swabs were analyzed from 175 subjects at enrollment, Day 3, and Day 5 for SARS-CoV-2 infectivity. Samples were stored at 4°C for up to 72 hours, shipped refrigerated, aliquoted, and stored at -80°C until testing. Vero E6 cell monolayers were infected with the sample for 1 hour. Culture medium was analyzed for viral load at 2 and 5 days post-infection by RT-PCR. Results: Seventy-eight (45%) participants, median 4.62 days (min. 1.40, max. 7.54) from symptom onset, had a positive SARS-CoV-2 culture at enrollment (52 on active and 26 on placebo). The percentage of participants with a positive viral culture at enrollment who were positive on Day 3 was 20.4% on active and 28% on placebo (p = 0.56). At day 5, 24% of placebo participants were culturethe positive compared to none treated with molnupiravir (p = 0.001). Between treatment, comparisons were performed using Fisher's exact test. Conclusion: This is the first demonstration of reduced infectiousness by antiviral therapy in people with SARS-2 infection. This simple, short-course oral therapy may benefit individuals and public health and is unlikely to be impacted by spike-protein variants.

ABSTRACT ß-d-N4-hydroxycytidine (NHC), the parent nucleoside of molnupiravir, a COVID-19 antiviral, was quantified at sites of SARS-CoV-2 transmission in twelve patients enrolled in AGILE CST-2 ( NCT04746183 ). Saliva, nasal and tear concentrations were 3, 21 and 22% that of plasma. Saliva and nasal NHC concentrations were significantly correlated with plasma ( p <0.0001).

Background: SARS-CoV-2 infectious virus isolation in the upper airway of COVID-19 patients is associated with higher levels of viral RNA. However, comprehensive evaluation of the relationships between host and disease factors and infectious, replication competent virus is needed. Methods: Symptomatic COVID-19 outpatients were enrolled from the United States. Clinical symptoms were recorded via patient diary. Nasopharyngeal swabs were collected to quantitate SARS-CoV-2 RNA by reverse transcriptase polymerase chain reaction and for infectious virus isolation in Vero E6-cells. SARS-CoV-2 antibodies were measured in serum using a validated ELISA assay. Findings: Among 204 participants within one week of reported symptom onset (median=5, IQR 4-5 days), median age was 40 (min-max: 18-82 years), median nasopharyngeal viral RNA was 6.5 (IQR 4.7-7.6 log10 copies/mL), and 26% had detectable SARS-CoV-2 antibodies at baseline. Infectious virus was recovered in 7% of participants with antibodies compared to 58% of participants without antibodies (probability ratio (PR)=0.12, 95% CI: 0.04, 0.36; p=0.00016). Infectious virus isolation was also associated with higher levels of viral RNA (mean RNA difference +2.6 log10, 95% CI: 2.2, 3.0; p<0.0001) and fewer days since symptom onset (PR=0.79, 95% CI: 0.71, 0.88 per day; p<0.0001). Interpretation: The presence of SARS-CoV-2 antibodies is strongly associated with clearance of infectious virus isolation. Seropositivity and viral RNA are likely more reliable markers of infectious virus suppression than subjective measure of COVID-19 symptoms. Virus-targeted treatment and prevention strategies should be administered as early as possible and ideally before seroconversion. Funding: Ridgeback Biotherapeutics, LP and NIH ClinicalTrials.gov Identifier: NCT04405570

Despite the availability of vaccines, there remains an urgent need for antiviral drugs with potent activity against SARS-CoV-2, the cause of COVID-19. Millions of people are immune-suppressed and may not be able to mount a fully protective immune response after vaccination. There is also an increasingly critical need for a drug to cover emerging SARS-CoV-2 variants, against which existing vaccines may be less effective. Here, we describe the evolution of molnupiravir (EIDD-2801, MK-4482), a broad-spectrum antiviral agent originally designed for the treatment of Alphavirus infections, into a potential drug for the prevention and treatment of COVID-19. When the pandemic began, molnupiravir was in pre-clinical development for the treatment of seasonal influenza. As COVID-19 spread, the timeline for the development program was moved forward significantly, and focus shifted to treatment of coronavirus infections. Real time consultation with regulatory authorities aided in making the acceleration of the program possible.

BACKGROUND:Easily distributed oral antivirals are urgently needed to treat coronavirus disease-2019 (COVID-19), prevent progression to severe illness, and block transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We report the results of a Phase 2a trial evaluating the safety, tolerability, and antiviral efficacy of molnupiravir in the treatment of COVID-19 ( ClinicalTrials.gov NCT04405570 ).METHODS:Eligible participants included outpatients with confirmed SARS-CoV-2 infection and symptom onset within 7 days. Participants were randomized 1:1 to 200 mg molnupiravir or placebo, or 3:1 to molnupiravir (400 or 800 mg) or placebo, twice-daily for 5 days. Antiviral activity was assessed as time to undetectable levels of viral RNA by reverse transcriptase polymerase chain reaction and time to elimination of infectious virus isolation from nasopharyngeal swabs.RESULTS:Among 202 treated participants, virus isolation was significantly lower in participants receiving 800 mg molnupiravir (1.9%) versus placebo (16.7%) at Day 3 (p = 0.02). At Day 5, virus was not isolated from any participants receiving 400 or 800 mg molnupiravir, versus 11.1% of those receiving placebo (p = 0.03). Time to viral RNA clearance was decreased and a greater proportion overall achieved clearance in participants administered 800 mg molnupiravir versus placebo (p = 0.01). Molnupiravir was generally well tolerated, with similar numbers of adverse events across all groups.CONCLUSIONS:Molnupiravir is the first oral, direct-acting antiviral shown to be highly effective at reducing nasopharyngeal SARS-CoV-2 infectious virus and viral RNA and has a favorable safety and tolerability profile.

Molnupiravir, EIDD-2801/MK-4482, the prodrug of the active antiviral ribonucleoside analog ß-d-N4-hydroxycytidine (NHC; EIDD-1931), has activity against a number of RNA viruses including severe acute respiratory syndrome coronavirus 2, severe acute respiratory syndrome coronavirus, Middle East respiratory syndrome coronavirus, and seasonal and pandemic influenza viruses.Single and multiple doses of molnupiravir were evaluated in this first-in-human, phase 1, randomized, double-blind, placebo-controlled study in healthy volunteers, which included evaluation of the effect of food on pharmacokinetics.EIDD-1931 appeared rapidly in plasma, with a median time of maximum observed concentration of 1.00 to 1.75 hours, and declined with a geometric half-life of approximately 1 hour, with a slower elimination phase apparent following multiple doses or higher single doses (7.1 hours at the highest dose tested). Mean maximum observed concentration and area under the concentration versus time curve increased in a dose-proportional manner, and there was no accumulation following multiple doses. When administered in a fed state, there was a decrease in the rate of absorption, but no decrease in overall exposure.Molnupiravir was well tolerated. Fewer than half of subjects reported an adverse event, the incidence of adverse events was higher following administration of placebo, and 93.3% of adverse events were mild. One discontinued early due to rash. There were no serious adverse events and there were no clinically significant findings in clinical laboratory, vital signs, or electrocardiography. Plasma exposures exceeded expected efficacious doses based on scaling from animal models; therefore, dose escalations were discontinued before a maximum tolerated dose was reached.

99 Background: Breast cancer patients taking tamoxifen (TAM) or an aromatase inhibitor (AI) often develop severe vasomotor symptoms (VMS) yet the only FDA approved non-hormonal treatment for VMS, 7.5 mg paroxetine, has a warning against concomitant use with TAM. Q-122, an orally-available small molecule, is being developed to address this unmet medical need. Results from the Phase 1b study, Q-1001, are presented. METHODS Q-1001 was a Phase 1 open-label, two-dose, dose-escalation study of the safety and preliminary effectiveness of Q-122 in females with breast cancer currently taking TAM or an AI and experiencing an average of at least 7-8 moderate to severe hot flashes per day. Key exclusion criteria included significant renal or hepatic disease, untreated hyperthyroidism and clinically significant abnormal laboratory findings. The study period included a 2 week drug-free screening phase, 28 day treatment phase, and 2 week drug-free follow-up period. Subjects were initially enrolled into Group 1 (100 mg Q-122) followed by Group 2 (200 mg Q-122). Safety was assessed by review of adverse events (AEs), physical findings and laboratory values. The primary efficacy endpoints were mean changes in frequency and severity (hot flash severity score, HFSS) of moderate and severe hot flashes from baseline to Week 4. Menopausal symptoms were assessed using the Greene Climacteric Scale (GCS). RESULTS 10 and 11 subjects received 100 and 200 mg Q-122 respectively; 8 subjects in each group completed the study. At the end of treatment for groups 1 and 2 respectively, the daily average frequency of hot flashes was reduced from 9.9 to 4.1 and from 8.6 to 3.2, and the mean HFSS was reduced by 62% and 68% from baseline values. Menopausal symptoms assessed using the GCS were significantly reduced from baseline (psychological: -82%; somatic: -65%; vasomotor: -65%). All AEs (n = 29) were either mild (79%) or moderate (21%) in severity and only 3 (all in one subject) were considered possibly related to study drug. CONCLUSIONS Treatment with Q-122 resulted in significant reduction in the frequency and severity of VMS and improvement in menopausal symptoms as assessed by the GCS. No safety issues associated with the use of Q-122 were identified in this study.

Progressive vaccinia (PV) is a rare but potentially lethal complication that develops in smallpox vaccine recipients with severely impaired cellular immunity. We describe a patient with PV who required treatment with vaccinia immune globulin and who received 2 investigational agents, ST-246 and CMX001. We describe the various molecular, pharmacokinetic, and immunologic studies that provided guidance to escalate and then successfully discontinue therapy. Despite development of resistance to ST-246 during treatment, the patient had resolution of PV. This case demonstrates the need for continued development of novel anti-orthopoxvirus pharmaceuticals and the importance of both intensive and timely clinical and laboratory support in management of PV.

IntroductionCMX001, an oral Lipid-Antiviral-Conjugate, generates high intracellular levels of cidofovir-diphosphate. CMX001 has potent in vitro activity against dsDNA viruses including herpesviruses, adenoviruses, polyomaviruses, and orthopoxviruses. Patients treated for these infections under individual EIND protocols experienced reductions in virus loads following CMX001 treatment; however, controlled human safety and efficacy data were previously not available.MethodsThis randomized, placebo-controlled, dose-escalation study (CMX001-201) enrolled adult allogeneic CMV-seropositive stem-cell transplant (SCT) recipients from 27 centers in USA. Patients, stratified post-engraftment by acute GVHD requiring systemic glucocorticoid therapy or CMV viremia, were randomized (3:1) to receive CMX001 or placebo into 5 sequential dose-escalating cohorts. Subjects were treated either once weekly (QW) or twice weekly (BIW) for 9 to 11 weeks until Week 13 post-transplant with a 4 to 8 week safety follow-up period. Virology and safety assessments were conducted weekly throughout the treatment period. A DSMB reviewed safety data and directed CMX001 doses for each cohort. Efficacy was measured by a composite endpoint of CMV disease or the appearance/progression of CMV viremia. Patients with these endpoints discontinued study drug and received anti-CMV treatment. This study was registered with ClinicalTrials.gov, NCT00942305.ResultsTableCMX001-201 Study. Selected Baseline Characteristics and Efficacy/Safety Summary Data (blinded data, as of 30 September 2011)Cohort40mg/placebo QW100mg/placebo QW200mg/placebo (QW)200mg/placebo BIW100mg/placebo BIWPatients enrolled, N4039534067Evaluable patients, N3337534067Baseline characteristicsPercent of Evaluable PatientsPeripheral Stem-Cell recipients85%89%72%75%87%Bone Marrow Recipients6%3%19%20%10%Umbilical Cord-Blood Recipients9%8%9%5%3%ATG Administration during Conditioning15%14%8%15%18%Acute GVHD at baseline18%16%11%17%9%CMV PCR negative before dosing70%84%76%78%84%Completed treatment36%49%43%28%57%Efficacy ResultsCMV Events to End of Treatment42%32%19%20%18%CMV DNAemia >1000 copies/mL45%27%21%18%12%Serious Adverse Events (SAE)Patients with SAEs Leading to Discontinuation21%12%9%25%6% Open table in a new tab ConclusionsIn this first Phase 2 trial of CMX001 ever conducted, a reduction in new or progressive CMV infection occurred in allogeneic SCT patient cohorts receiving higher doses of CMX001 (≥200mg weekly). An increased incidence of diarrhea occurred in patients receiving the highest dose of CMX001 (200mg BIW). CMX001 has potential as a prophylactic antiviral agent in this population. IntroductionCMX001, an oral Lipid-Antiviral-Conjugate, generates high intracellular levels of cidofovir-diphosphate. CMX001 has potent in vitro activity against dsDNA viruses including herpesviruses, adenoviruses, polyomaviruses, and orthopoxviruses. Patients treated for these infections under individual EIND protocols experienced reductions in virus loads following CMX001 treatment; however, controlled human safety and efficacy data were previously not available.