Digital wearable insole-based identification of knee arthropathies and gait signatures using machine learning

Gait is impaired in musculoskeletal conditions, such as knee arthropathy. Gait analysis is used in clinical practice to inform diagnosis and to monitor disease progression or intervention response. However, clinical gait analysis relies on subjective visual observation of walking, as objective gait analysis has not been possible within clinical settings due to the expensive equipment, large-scale facilities, and highly trained staff required. Relatively low-cost wearable digital insoles may offer a solution to these challenges. In this work, we demonstrate how a digital insole measuring osteoarthritis-specific gait signatures yields similar results to the clinical gait-lab standard. To achieve this, we constructed a machine learning model, trained on force plate data collected in participants with knee arthropathy and controls. This model was highly predictive of force plate data from a validation set (area under the receiver operating characteristics curve [auROC] = 0.86; area under the precision-recall curve [auPR] = 0.90) and of a separate, independent digital insole dataset containing control and knee osteoarthritis subjects (auROC = 0.83; auPR = 0.86). After showing that digital insole derived gait characteristics are comparable to traditional gait measurements, we next showed that a single stride of raw sensor time series data could be accurately assigned to each subject, highlighting that individuals using digital insoles can be identified by their gait characteristics. This work provides a framework for a promising alternative to traditional clinical gait analysis methods, adds to the growing body of knowledge regarding wearable technology analytical pipelines, and supports clinical development of at-home gait assessments, with the potential to improve the ease, frequency, and depth of patient monitoring.

Thematic analysis to explore patients' experiences with long COVID-19: a conceptual model of symptoms and impacts on daily lives

OBJECTIVES

There is limited qualitative research on patients' experiences with long COVID-19, and how specific symptoms impact their daily lives. The study aimed to understand patients' lived experiences of long COVID-19 and to develop a conceptual model representing the symptoms and their impact on overall quality of life.

SETTING

Qualitative study consisting of a comprehensive literature review, and in-depth clinician and patient semistructured interviews.

PARTICIPANTS

Forty-one adult patients with long COVID-19, of whom 18 (44%) were recruited through Regeneron Pharmaceuticals's clinical trials and 23 (56%) through recruitment agencies; 85.4% were female and 73.2% were White. Five independent clinicians treating patients with long COVID-19 were interviewed. Concept saturation was also assessed.

PRIMARY AND SECONDARY OUTCOMES

Interview transcripts were analysed thematically to identify concepts of interest spontaneously mentioned by patients, including symptoms and their impacts on daily life, to guide the development of the conceptual model.

RESULTS

Findings from the literature review and clinician and patient interviews resulted in the development of a conceptual model comprising two overarching domains: symptoms (upper respiratory tract, lower respiratory tract, smell and taste, systemic, gastrointestinal, neurocognitive and other) and impacts (activities of daily living, instrumental activities of daily living, physical impacts, emotional, social/leisure activities and professional impacts). Saturation was achieved for the reported impacts. The symptoms reported were heterogenic; neurocognitive symptoms, such as numbness, ringing in ears, haziness, confusion, forgetfulness/memory problems, brain fog, concentration, difficulties finding the right word and challenges with fine motor skills, were particularly pertinent for several months.

CONCLUSION

The conceptual model, developed based on patient experience data of long COVID-19, highlighted numerous symptoms that impact patients' physical and mental well-being, and suggests humanistic unmet needs. Prospective real-world studies are warranted to understand the pattern of long COVID-19 experienced in larger samples over longer periods of time.

Monoclonal antibodies against GFRα3 are efficacious against evoked hyperalgesic and allodynic responses in mouse join pain models but, one of these, REGN5069, was not effective against pain in a randomized, placebo-controlled clinical trial in patients with osteoarthritis pain

The artemin-GFRα3 signaling pathway has been implicated in various painful conditions including migraine, cold allodynia, hyperalgesia, inflammatory bone pain, and mouse knees contain GFRα3-immunoreactive nerve endings. We developed high affinity mouse (REGN1967) and human (REGN5069) GFRα3-blocking monoclonal antibodies and, following in vivo evaluations in mouse models of chronic joint pain (osteoarthritic-like and inflammatory), conducted a first-in-human phase 1 pharmacokinetics (PK) and safety trial of REGN5069 (NCT03645746) in healthy volunteers, and a phase 2 randomized placebo-controlled efficacy and safety trial of REGN5069 (NCT03956550) in patients with knee osteoarthritis (OA) pain. In three commonly used mouse models of chronic joint pain (destabilization of the medial meniscus, intra-articular monoiodoacetate, or Complete Freund's Adjuvant), REGN1967 and REGN5069 attenuated evoked behaviors including tactile allodynia and thermal hyperalgesia without discernably impacting joint pathology or inflammation, prompting us to further evaluate REGN5069 in humans. In the phase 1 study in healthy subjects, the safety profiles of single doses of REGN5069 up to 3000 mg (intravenous) or 600 mg (subcutaneous) were comparable to placebo; PK were consistent with a monoclonal antibody exhibiting target-mediated disposition. In the phase 2 study in patients with OA knee pain, two doses of REGN5069 (100 mg or 1000 mg intravenous every 4 weeks) for 8 weeks failed to achieve the 12-week primary and secondary efficacy endpoints relative to placebo. In addition to possible differences in GFRα3 biology between mice and humans, we highlight here differences in experimental parameters that could have contributed to a different profile of efficacy in mouse models versus human OA pain. Additional research is required to more fully evaluate any potential role of GFRα3 in human pain.

Effectiveness of Casirivimab and Imdevimab Antibody Combination in Immunocompromised Hospitalized Patients With Coronavirus Disease 2019: A Post Hoc Analysis in a Phase 1/2/3 Double-Blind Trial

Background

Individuals who are immunocompromised (IC) are at high risk for severe coronavirus disease 2019 (COVID-19).

Methods

Post hoc analyses of a double-blind trial conducted prior to Omicron (June 2020-April 2021), in hospitalized patients with COVID-19 assessed viral load, clinical outcomes, and safety of casirivimab plus imdevimab (CAS + IMD) versus placebo in IC versus overall study patients.

Results

Ninety-nine of 1940 (5.1%) patients were IC. IC versus overall patients were more frequently seronegative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies (68.7% vs 41.2%) and had higher median baseline viral loads (7.21 vs 6.32 log₁₀ copies/mL). On placebo, IC versus overall patients had slower viral load declines. CAS + IMD reduced viral load in IC and overall patients; least-squares mean difference versus placebo in time-weighted average change from baseline viral load at day 7 was -0.69 (95% confidence interval [CI], -1.25 to -.14) log₁₀ copies/mL for IC patients and -0.31 (95% CI, -.42 to -.20) log₁₀ copies/mL for overall patients. For IC patients, the cumulative incidence of death or mechanical ventilation at day 29 was lower with CAS + IMD (11.0%) versus placebo (17.2%), consistent with overall patients (15.7% CAS + IMD vs 18.3% placebo). IC and overall patients receiving CAS + IMD exhibited similar rates of treatment-emergent adverse events (30.4% and 26.6%, respectively), grade ≥2 hypersensitivity or infusion-related reactions (1.4% and 2.5%), and deaths (8.7% and 12.2%).

Conclusions

IC patients were more likely to exhibit high viral loads and be seronegative at baseline. For susceptible SARS-CoV-2 variants, CAS + IMD reduced viral load and resulted in fewer death or mechanical ventilation events in IC and overall study patients. There were no new safety findings among IC patients. Clinical Trials Registration. NCT04426695.

Casirivimab and Imdevimab Treatment Reduces Viral Load and Improves Clinical Outcomes in Seropositive Hospitalized COVID-19 Patients with Nonneutralizing or Borderline Neutralizing Antibodies

We conducted a post hoc analysis in seropositive patients who were negative or borderline for functional neutralizing antibodies (NAbs) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at baseline from a phase 1, 2, and 3 trial of casirivimab and imdevimab (CAS+IMD) treatment in hospitalized coronavirus disease 2019 (COVID-19) patients on low-flow or no supplemental oxygen prior to the emergence of Omicron-lineage variants. Patients were randomized to a single dose of 2.4 g CAS+IMD, 8.0 g CAS+IMD, or placebo. Patients seropositive for anti-SARS-CoV-2 antibodies at baseline were analyzed by their baseline neutralizing antibody status. At baseline, 20.6% (178/864) of seropositive patients were negative or borderline for neutralizing antibodies, indicating negative or very low functionally neutralizing anti-SARS-CoV-2 antibodies. CAS+IMD reduced viral load in patients who were negative or borderline for neutralizing antibodies versus placebo, but not in patients who were positive for neutralizing antibodies. In patients who were negative or borderline for neutralizing antibodies, we observed a trend in reduction of the proportion of patients who died or required mechanical ventilation, as well as in all-cause mortality, by day 29 with CAS+IMD versus placebo. The proportions of patients who died or required mechanical ventilation from days 1 to 29 were 19.1% in the placebo group and 10.9% in the CAS+IMD combined-dose group, and the proportions of patients who died (all-cause mortality) from days 1 to 29 were 16.2% in the placebo group and 9.1% in the CAS+IMD combined-dose group. In patients who were positive for neutralizing antibodies, no measurable harm or benefit was observed in either the proportion of patients who died or required mechanical ventilation or the proportion of patients who died (all-cause mortality). In hospitalized COVID-19 patients on low-flow or no supplemental oxygen, CAS+IMD reduced viral load, the risk of death or mechanical ventilation, and all-cause mortality in seropositive patients who were negative or borderline for neutralizing antibodies. IMPORTANCE The clinical benefit of CAS+IMD in hospitalized seronegative patients with COVID-19 has previously been demonstrated, although these studies observed no clinical benefit in seropositive patients. As the prevalence of SARS-CoV-2-seropositive individuals rises due to both vaccination and previous infection, it is important to understand whether there is a subset of hospitalized patients with COVID-19 with antibodies against SARS-CoV-2 who could benefit from anti-SARS-CoV-2 monoclonal antibody treatment. This post hoc analysis demonstrates that there is a subset of hospitalized seropositive patients with inadequate SARS-CoV-2-neutralizing antibodies (i.e., those who were negative or borderline for neutralizing antibodies) who may still benefit from CAS+IMD treatment if infected with a susceptible SARS-CoV-2 variant. Therefore, utilizing serostatus alone to guide treatment decisions for patients with COVID-19 may fail to identify those seropositive patients who could benefit from anti-SARS-CoV-2 monoclonal antibody therapies known to be effective against circulating strains, dependent upon how effectively their endogenous antibodies neutralize SARS-CoV-2.

1079. Casirivimab and Imdevimab (CAS + IMD) Antibody Combination for the Treatment of Immunocomprised Hospitalized Patients with COVID-19

Background

Immunocompromised (IC) individuals are at high risk for severe COVID-19, with high morbidity and mortality. CAS+IMD is a monoclonal antibody combination that neutralizes susceptible SARS-CoV-2 variants. We examined the natural history of COVID-19 and the efficacy and safety of CAS+IMD in IC patients (pts) hospitalized with COVID-19.

Methods

In a phase 1/2/3 double-blind trial (NCT04426695) conducted Jun 2020 to Apr 2021, prior to the emergence of Omicron-lineage variants, hospitalized COVID-19 pts were randomized 1:1:1 to a single 2.4 g or 8.0 g dose (combined for analyses) of CAS+IMD or placebo (P). Post hoc analyses assessed change in viral load (VL), clinical outcomes (death or mechanical ventilation [MV]), and safety for IC pts with B-cell deficiency or dysfunction (Table 1) vs all pts.

Results

99/1940 (5.1%) treated pts were identified as IC (Table 2). At baseline, IC vs all pts were more likely to be seronegative for SARS-CoV-2 antibodies (68.7% vs 41.2%), and to have higher median VLs (7.21 vs 6.32 log10 copies/mL). Compared to all pts receiving P, IC pts receiving P had slower VL declines. Treatment with CAS+IMD led to a reduction in VL from baseline, with a least-squares mean time-weighted average change in VL difference vs P at Day 7 for IC pts of -0.69 (95% CI: -1.25, -0.41) vs -0.31 (CI: -0.42, -0.20) for all pts; treatment benefit persisted through Day 29 (Fig. 1). Although sample size was small for IC pts, trends in clinical outcomes of death or MV at Day 29 for IC pts (7/64 [11.0%] CAS+IMD vs 6/35 [17.2%] P) were consistent with those in all pts (200/1307 [15.3%] CAS+IMD vs 113/633 [17.9%] P). IC vs all pts treated with CAS+IMD exhibited similar rates of treatment emergent adverse events (TEAEs, 30.4% vs 26.6%), AEs of special interest (grade ≥2 hypersensitivity or infusion-related reactions; 1.4% vs 2.5%), and death (8.7% vs 12.2%; Table 3). IC and all pts exhibited fewer TEAEs with CAS+IMD vs P.

Conclusion

IC vs all pts hospitalized with COVID-19 were more likely to exhibit high VLs at baseline and to be seronegative. In the study, a single dose of CAS+IMD significantly reduced VL in IC pts (for variants circulating at the time, predominantly Alpha) and resulted in fewer events of death or MV. There were no new safety findings in IC pts vs all study pts.

Disclosures

Selin Somersan-Karakaya, PhD, BARDA: Grant/Research Support|Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Eleftherios Mylonakis, MD, PhD, Chemic Labs/KODA Therapeutics: Grant/Research Support|Cidara: Grant/Research Support|Leidos Biomedical Research Inc./NCI: Grant/Research Support|NIH/NIAID, NIH/NIGMS: Grant/Research Support|Pfizer: Grant/Research Support|Regeneron Pharmaceuticals, Inc.: Grant/Research Support|SciClone Pharmaceuticals: Grant/Research Support Ernesto Oviedo-Orta, MD, PhD, MBA, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Meagan P. O’Brien, MD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Veronica Mas Casullo, MD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Jenni Mou, PhD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Jing Xiao, PhD, Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Rafia Bhore, PhD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Adnan Mahmood, MD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Andrea T. Hooper, PhD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Mohamed Hussein, PhD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Shazia Ali, PharmD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Eduardo Forleo-Neto, MD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Gary A. Herman, MD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds Boaz Hirshberg, MD, MBA, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds David M. Weinreich, MD, Regeneron Pharmaceuticals, Inc.: Employement|Regeneron Pharmaceuticals, Inc.: Stocks/Bonds.

Efficacy and safety of a single dose of casirivimab and imdevimab for the prevention of COVID-19 over an 8-month period: a randomised, double-blind, placebo-controlled trial

BACKGROUND

There is an unmet need for COVID-19 prevention in patient populations who have not mounted or are not expected to mount an adequate immune response to complete COVID-19 vaccination. We previously reported that a single subcutaneous 1200 mg dose of the monoclonal antibody combination casirivimab and imdevimab (CAS + IMD) prevented symptomatic SARS-CoV-2 infections by 81·4% in generally healthy household contacts of SARS-CoV-2-infected individuals over a 1-month efficacy assessment period. Here we present additional results, including the 7-month follow-up period (months 2-8), providing additional insights about the potential for efficacy in pre-exposure prophylaxis settings.

METHODS

This was a randomised, double-blind, placebo-controlled trial done in the USA, Romania, and Moldova in 2020-2021, before the emergence of omicron (B.1.1.529) and omicron-lineage variants. Uninfected and unvaccinated household contacts of infected individuals, judged by the investigator to be in good health, were randomly assigned (1:1) to receive 1200 mg CAS + IMD or placebo by subcutaneous injection according to a central randomisation scheme provided by an interactive web response system; randomisation was stratified per site by the test results of a local diagnostic assay for SARS-CoV-2 and age group at baseline. COVID-19 vaccines were prohibited before randomisation, but participants were allowed to receive COVID-19 vaccination during the follow-up period. Participants who developed COVID-19 symptoms during the follow-up period underwent RT-PCR testing. Prespecified endpoints included the proportion of previously uninfected and baseline-seronegative participants (seronegative-modified full analysis set) who had RT-PCR-confirmed COVID-19 in the follow-up period (post-hoc for the timepoints of months 2-5 and 6-8 only) and underwent seroconversion (ie, became seropositive, considered a proxy for any SARS-CoV-2 infections [symptomatic and asymptomatic]; prespecified up to day 57, post-hoc for all timepoints thereafter). We also assessed the incidence of treatment-emergent adverse events. This study is registered with ClinicalTrials.gov, NCT04452318.

FINDINGS

From July 13, 2020, to Oct 4, 2021, 2317 participants who were RT-PCR-negative for SARS-CoV-2 were randomly assigned, of whom 1683 (841 assigned to CAS + IMD and 842 assigned to placebo) were seronegative at baseline. During the entirety of the 8-month study, CAS + IMD reduced the risk of COVID-19 by 81·2% (nominal p<0·0001) versus placebo (prespecified analysis). During the 7-month follow-up period, protection was greatest during months 2-5, with a 100% relative risk reduction in COVID-19 (nominal p<0·0001; post-hoc analysis). Efficacy waned during months 6-8 (post-hoc analysis). Seroconversion occurred in 38 (4·5%) of 841 participants in the CAS + IMD group and in 181 (21·5%) of 842 in the placebo group during the 8-month study (79·0% relative risk reduction vs placebo; nominal p<0·0001). Six participants in the placebo group were hospitalised due to COVID-19 versus none who received CAS + IMD. Serious treatment-emergent adverse events (including COVID-19) were reported in 24 (1·7%) of 1439 participants receiving CAS + IMD and in 23 (1·6%) of 1428 receiving placebo. Five deaths were reported, none of which were due to COVID-19 or related to the study drugs.

INTERPRETATION

CAS + IMD is not authorised in any US region as of Jan 24, 2022, because data show that CAS + IMD is not active against omicron-lineage variants. In this study, done before the emergence of omicron-lineage variants, a single subcutaneous 1200 mg dose of CAS + IMD protected against COVID-19 for up to 5 months of community exposure to susceptible strains of SARS-CoV-2 in the pre-exposure prophylaxis setting, in addition to the post-exposure prophylaxis setting that was previously shown.

FUNDING

Regeneron Pharmaceuticals, F Hoffmann-La Roche, US National Institute of Allergy and Infectious Diseases, US National Institutes of Health.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL TRIALS REGISTRATION

NCT04315298.

Casirivimab and Imdevimab for the Treatment of Hospitalized Patients With COVID-19

BACKGROUND

The open-label RECOVERY study reported improved survival in hospitalized, SARS-CoV-2 seronegative patients treated with casirivimab and imdevimab (CAS + IMD).

METHODS

In this phase 1/2/3, double-blind, placebo-controlled trial conducted prior to widespread circulation of Delta and Omicron, hospitalized COVID-19 patients were randomized (1:1:1) to 2.4 g or 8.0 g CAS + IMD or placebo, and characterized at baseline for viral load and SARS-CoV-2 serostatus.

RESULTS

In total, 1336 patients on low-flow or no supplemental (low-flow/no) oxygen were treated. The primary endpoint was met in seronegative patients, the least-squares mean difference (CAS + IMD versus placebo) for time-weighted average change from baseline in viral load through day 7 was -0.28 log10 copies/mL (95% confidence interval [CI], -.51 to -.05; P = .0172). The primary clinical analysis of death or mechanical ventilation from day 6 to 29 in patients with high viral load had a strong positive trend but did not reach significance. CAS + IMD numerically reduced all-cause mortality in seronegative patients through day 29 (relative risk reduction, 55.6%; 95% CI, 24.2%-74.0%). No safety concerns were noted.

CONCLUSIONS

In hospitalized COVID-19 patients on low-flow/no oxygen, CAS + IMD reduced viral load and likely improves clinical outcomes in the overall population, with the benefit driven by seronegative patients, and no harm observed in seropositive patients.

CLINICAL TRIALS REGISTRATION

NCT04426695.

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

Background

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

Methods

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

Results

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

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

Conclusion

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

Disclosures

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

The monoclonal antibody combination REGEN-COV protects against SARS-CoV-2 mutational escape in preclinical and human studies

Monoclonal antibodies against SARS-CoV-2 are a clinically validated therapeutic option against COVID-19. Because rapidly emerging virus mutants are becoming the next major concern in the fight against the global pandemic, it is imperative that these therapeutic treatments provide coverage against circulating variants and do not contribute to development of treatment-induced emergent resistance. To this end, we investigated the sequence diversity of the spike protein and monitored emergence of virus variants in SARS-COV-2 isolates found in COVID-19 patients treated with the two-antibody combination REGEN-COV, as well as in preclinical in vitro studies using single, dual, or triple antibody combinations, and in hamster in vivo studies using REGEN-COV or single monoclonal antibody treatments. Our study demonstrates that the combination of non-competing antibodies in REGEN-COV provides protection against all current SARS-CoV-2 variants of concern/interest and also protects against emergence of new variants and their potential seeding into the population in a clinical setting.

Nitrooxidoreductase Rv2466c-Dependent Fluorescent Probe for Mycobacterium tuberculosis Diagnosis and Drug Susceptibility Testing

Firstly, this study demonstrated that natural product-inspired coumarin-based nitrofuranyl calanolides (NFCs) can form the Rv2466c-mycothiol (MSH)-NFC (RvMN) ternary complex via NFC binding to W21, N51, and Y61 of Rv2466c and be specifically reduced by Rv2466c, which is accompanied by the generation of a high level of fluorescence. Additionally, the results unveiled that the acetylated cysteine-glucosamine (AcCys-GlcN) motif of MSH is sufficient to interact with Rv2466c and adopt the active conformation that is essential for fully reducing NFCs. Further clinical translational investigation in this Article indicated that the novel fluorescent NFC probe can serve as a much needed high-throughput and low-cost detection method for detection of living Mycobacterium tuberculosis ( Mtb) and can precisely determine MIC values for a full range of available drugs. This method can greatly facilitate the development of phenotypic drug-susceptibility testing (pDST) that will allow the point-of-care treatment of tuberculosis (TB) within a week after diagnosis.

Identification of a Mycothiol-Dependent Nitroreductase from Mycobacterium tuberculosis

The success of Mycobacterium tuberculosis (Mtb) as a pathogen depends on the redundant and complex mechanisms it has evolved for resisting nitrosative and oxidative stresses inflicted by host immunity. Improving our understanding of these defense pathways can reveal vulnerable points in Mtb pathogenesis. In this study, we combined genetic, structural, computational, biochemical, and biophysical approaches to identify a novel enzyme class represented by Rv2466c. We show that Rv2466c is a mycothiol-dependent nitroreductase of Mtb and can reduce the nitro group of a novel mycobactericidal compound using mycothiol as a cofactor. In addition to its function as a nitroreductase, Rv2466c confers partial protection to menadione stress.

Visualization of the Charcoal Agar Resazurin Assay for Semi-quantitative, Medium-throughput Enumeration of Mycobacteria

There is an urgent need to discover and progress anti-infectives that shorten the duration of tuberculosis (TB) treatment. Mycobacterium tuberculosis, the etiological agent of TB, is refractory to rapid and lasting chemotherapy due to the presence of bacilli exhibiting phenotypic drug resistance. The charcoal agar resazurin assay (CARA) was developed as a tool to characterize active molecules discovered by high-throughput screening campaigns against replicating and non-replicating M. tuberculosis. Inclusion of activated charcoal in bacteriologic agar medium helps mitigate the impact of compound carry-over, and eliminates the requirement to pre-dilute cells prior to spotting on CARA microplates. After a 7-10 day incubation period at 37 °C, the reduction of resazurin by mycobacterial microcolonies growing on the surface of CARA microplate wells permits semi-quantitative assessment of bacterial numbers via fluorometry. The CARA detects approximately a 2-3 log₁₀ difference in bacterial numbers and predicts a minimal bactericidal concentration leading to ≥99% bacterial kill (MBC_≥99). The CARA helps determine whether a molecule is active on bacilli that are replicating, non-replicating, or both. Pilot experiments using the CARA facilitate the identification of which concentration of test agent and time of compound exposure require further evaluation by colony forming unit (CFU) assays. In addition, the CARA can predict if replicating actives are bactericidal or bacteriostatic.

N-methylation of a bactericidal compound as a resistance mechanism in Mycobacterium tuberculosis

The rising incidence of antimicrobial resistance (AMR) makes it imperative to understand the underlying mechanisms. Mycobacterium tuberculosis (Mtb) is the single leading cause of death from a bacterial pathogen and estimated to be the leading cause of death from AMR. A pyrido-benzimidazole, 14, was reported to have potent bactericidal activity against Mtb. Here, we isolated multiple Mtb clones resistant to 14. Each had mutations in the putative DNA-binding and dimerization domains of rv2887, a gene encoding a transcriptional repressor of the MarR family. The mutations in Rv2887 led to markedly increased expression of rv0560c. We characterized Rv0560c as an S-adenosyl-L-methionine-dependent methyltransferase that N-methylates 14, abolishing its mycobactericidal activity. An Mtb strain lacking rv0560c became resistant to 14 by mutating decaprenylphosphoryl-β-d-ribose 2-oxidase (DprE1), an essential enzyme in arabinogalactan synthesis; 14 proved to be a nanomolar inhibitor of DprE1, and methylation of 14 by Rv0560c abrogated this activity. Thus, 14 joins a growing list of DprE1 inhibitors that are potently mycobactericidal. Bacterial methylation of an antibacterial agent, 14, catalyzed by Rv0560c of Mtb, is a previously unreported mechanism of AMR.

Identification of Novel Anti-mycobacterial Compounds by Screening a Pharmaceutical Small-Molecule Library against Nonreplicating Mycobacterium tuberculosis

Identification of compounds that target metabolically diverse subpopulations of Mycobacterium tuberculosis (Mtb) may contribute to shortening the course of treatment for tuberculosis. This study screened 270,000 compounds from GlaxoSmithKline's collection against Mtb in a nonreplicating (NR) state imposed in vitro by a combination of four host-relevant stresses. Evaluation of 166 confirmed hits led to detailed characterization of 19 compounds for potency, specificity, cytotoxicity, and stability. Compounds representing five scaffolds depended on reactive nitrogen species for selective activity against NR Mtb, and two were stable in the assay conditions. Four novel scaffolds with activity against replicating (R) Mtb were also identified. However, none of the 19 compounds was active against Mtb in both NR and R states. There was minimal overlap between compounds found active against NR Mtb and those previously identified as active against R Mtb, supporting the hypothesis that NR Mtb depends on distinct metabolic pathways for survival.

Synthetic calanolides with bactericidal activity against replicating and nonreplicating Mycobacterium tuberculosis

It is urgent to introduce new drugs for tuberculosis to shorten the prolonged course of treatment and control drug-resistant Mycobacterium tuberculosis (Mtb). One strategy toward this goal is to develop antibiotics that eradicate both replicating (R) and nonreplicating (NR) Mtb. Naturally occurring (+)-calanolide A was active against R-Mtb. The present report details the design, synthesis, antimycobacterial activities, and structure-activity relationships of synthetic calanolides. We identified potent dual-active nitro-containing calanolides with minimal in vitro toxicity that were cidal to axenic Mtb and Mtb in human macrophages, while sparing Gram-positive and -negative bacteria and yeast. Two of the nitrobenzofuran-containing lead compounds were found to be genotoxic to mammalian cells. Although genotoxicity precluded clinical progression, the profound, selective mycobactericidal activity of these calanolides will be useful in identifying pathways for killing both R- and NR-Mtb, as well as in further structure-based design of more effective and drug-like antimycobacterial agents.