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SUMMARYThe recently emerged SARS-CoV-2 Omicron variant harbors 37 amino acid substitutions in the spike (S) protein, 15 of which are in the receptor-binding domain (RBD), thereby raising concerns about the effectiveness of available vaccines and antibody therapeutics. Here, we show that the Omicron RBD binds to human ACE2 with enhanced affinity relative to the Wuhan-Hu-1 RBD and acquires binding to mouse ACE2. Severe reductions of plasma neutralizing activity were observed against Omicron compared to the ancestral pseudovirus for vaccinated and convalescent individuals. Most (26 out of 29) receptor-binding motif (RBM)-directed monoclonal antibodies (mAbs) lost in vitro neutralizing activity against Omicron, with only three mAbs, including the ACE2-mimicking S2K146 mAb1, retaining unaltered potency. Furthermore, a fraction of broadly neutralizing sarbecovirus mAbs recognizing antigenic sites outside the RBM, including sotrovimab2, S2X2593 and S2H974, neutralized Omicron. The magnitude of Omicron-mediated immune evasion and the acquisition of binding to mouse ACE2 mark a major SARS-CoV-2 mutational shift. Broadly neutralizing sarbecovirus mAbs recognizing epitopes conserved among SARS-CoV-2 variants and other sarbecoviruses may prove key to controlling the ongoing pandemic and future zoonotic spillovers.

Background COVID-19 disproportionately results in hospitalization and death in older patients and those with underlying comorbidities. Sotrovimab is a pan-sarbecovirus monoclonal antibody that binds a highly conserved epitope of the SARS-CoV-2 receptor binding domain and has an Fc modification that increases half-life. Sotrovimab retains activity against UK, S. Africa, Brazil, India, New York and California variants in vitro. Objectives To evaluate the efficacy and safety of treatment with sotrovimab in high-risk, non-hospitalized patients with mild/moderate COVID-19, as part of the COMET-ICE clinical trial. Methods Multicenter, double-blind, phase 3 trial in non-hospitalized patients with symptomatic COVID-19 and ≥1 risk factor for disease progression were randomized 1:1 to an IV infusion of sotrovimab 500 mg or placebo. The primary efficacy endpoint was the proportion of patients with COVID-19 progression, defined as hospitalization > 24 hours or death, due to any cause, ≤29 days of randomization. Results The study met the pre-defined primary efficacy endpoint in a preplanned interim analysis: the risk of COVID-19 progression was significantly reduced by 85% (97.24% CI, 44% to 96%; P = 0.002) in 583 patients. In the final intention-to-treat analysis (N = 1057), the adjusted relative risk reduction was 79% (95% CI, 50% to 91%; p< 0.001) through Day 29 in recipients of sotrovimab (n=528) vs. placebo (n=529). Treatment with sotrovimab (ITT) resulted in a numerical reduction in the need for ER visits for illness management, hospitalization for acute illness management (any duration) or death (any cause) compared to placebo. No participants on sotrovimab required ICU admission, compared to 9 participants on placebo, of whom 4 participants required mechanical ventilation. No participants who received sotrovimab died, compared to 4 participants on placebo. The incidence of adverse events was similar between treatment arms and SAEs were numerically more common in the placebo arm. Conclusion Treatment with sotrovimab 500 mg IV resulted in a clinically and statistically significant reduction in progression of COVID-19 to hospitalization or death in patients with mild/moderate disease and was well-tolerated. Study funding GSK & VIR; NCT04545060 Disclosures Jaynier Moya, MD, VIR Biotechnology (Other Financial or Material Support, Jaynier Moya received non-financial support for serving as a clinical trial investigator for Vir Biotechnology) Diego Rodrigues Falci, MD, MSc, PhD, Gilead Sciences (Grant/Research Support, Scientific Research Study Investigator, Speaker's Bureau)GSK (Grant/Research Support, Scientific Research Study Investigator, Advisor or Review Panel member)MSD (Speaker's Bureau)Pfizer (Speaker's Bureau)United Medical (Speaker's Bureau, Other Financial or Material Support) Joel Solis, MD, VIR Biotechnology (Other Financial or Material Support, Joel Solis received non-financial support for serving as a clinical trial investigator for Vir Biotechnology) Hanzhe Zheng, PhD, VIR Biotechnology (Employee) Nicola Scott, MSc, GlaxoSmithKline (Employee, Shareholder) Andrea L. Cathcart, PhD, Gilead (Shareholder)VIR (Employee, Shareholder) Christy Hebner, PhD, Vir Biotechnology (Employee, Shareholder) Jennifer Sager, PhD, GSK (Other Financial or Material Support)Vir Biotechnology (Employee, Shareholder) Erik Mogalian, PharmD, PhD, Vir Biotechnology (Employee, Shareholder) Daren Austin, PhD, GlaxoSmithKline (Employee, Shareholder) Amanda Peppercorn, MD, GlaxoSmithKline (Employee) Elizabeth L. Alexander, MD, MSc, GlaxoSmithKline (Grant/Research Support, Other Financial or Material Support)VIR Biotechnology (Employee, Shareholder, GSK pharmaceuticals) Wendy W. Yeh, MD, Vir Biotechnology (Employee) Almena Free, MD, Amgen (Scientific Research Study Investigator)Astra Zeneca (Scientific Research Study Investigator)Cardurian (Scientific Research Study Investigator)Coherus (Scientific Research Study Investigator)Freenome (Scientific Research Study Investigator)GlaxoSmithKline/Vir (Scientific Research Study Investigator)Ionis (Scientific Research Study Investigator)Kowa (Scientific Research Study Investigator)New Amsterdam (Scientific Research Study Investigator)Regenacy (Scientific Research Study Investigator)Romark (Scientific Research Study Investigator)Scynexis (Scientific Research Study Investigator) Cynthia Brinson, MD, Abbvie (Scientific Research Study Investigator)BI (Scientific Research Study Investigator)Gilead Sciences Inc. (Scientific Research Study Investigator, Advisor or Review Panel member, Speaker's Bureau, Personal fees)GSK (Scientific Research Study Investigator)Novo Nordisk (Scientific Research Study Investigator)ViiV Healthcare (Scientific Research Study Investigator, Advisor or Review Panel member, Speaker's Bureau) Melissa Aldinger, PharmD, VIR Biotechnology (Employee) Adrienne Shapiro, MD, PhD, Vir Biotechnology (Scientific Research Study Investigator)

New drugs with novel mechanisms of resistance are desperately needed to address both community and nosocomial infections due to Gram-negative bacteria. One such potential target is LpxC, an essential enzyme that catalyzes the first committed step of lipid A biosynthesis. Achaogen conducted an extensive research campaign to discover novel LpxC inhibitors with activity against Pseudomonas aeruginosa. We report here the in vitro antibacterial activity and pharmacodynamics of ACHN-975, the only molecule from these efforts and the first ever LpxC inhibitor to be evaluated in phase 1 clinical trials. In addition, we describe the profiles of three additional LpxC inhibitors that were identified as potential lead molecules. These efforts did not produce an additional development candidate with a sufficiently large therapeutic window and the program was subsequently terminated.

Three-dimensional (3D) epithelial culture systems recreate the cardinal features of glandular epithelium in vivo and represent a valuable tool for modeling breast cancer initiation and progression in a structurally appropriate context. 3D models have emerged as a powerful method to interrogate the biological activities of cancer genes and oncogenic pathways, and recent studies have poignantly illustrated their utility in dissecting the emerging role of tensional force in regulating epithelial tissue homeostasis. We review how 3D models are being used to investigate fundamental cellular and biophysical mechanisms associated with breast cancer progression that have not been readily amenable to traditional genetic or biochemical analysis.