1154. Safety, Tolerability, and Viral Pharmacodynamics of the IgG Monoclonal Antibody Sotrovimab Administered via Intramuscular Injection for the Treatment of Early Mild-to-Moderate COVID-19

Background There is a continued need for therapeutics for the treatment of COVID-19, including intramuscular (IM) agents, which will enable broader use across a variety of healthcare delivery settings. Methods COMET-PEAK (NCT04779879) is a 3-part study evaluating the safety, tolerability, pharmacokinetics (Part A), and viral pharmacodynamics (PD) of sotrovimab as treatment in adults ≥ 18 years with early mild/moderate COVID-19. In Parts B and C, the safety, tolerability and viral PD of sotrovimab administered as a 500 mg intravenous (IV) infusion or as a 500 mg or 250 mg IM injection, respectively, was evaluated. The primary objective for Parts B and C was to compare the virologic response of sotrovimab IM to IV, with an endpoint of mean area under the curve (AUC) of SARS-CoV-2 viral load as measured by qRT-PCR from Day 1 to Day 8 (AUCD1-8) in nasopharyngeal swabs and predefined 90% confidence interval (CI) limits of 0.5-2.0 indicating equivalence. Results A total of 167 and 157 participants were enrolled in Part B and C, respectively, from February-July 2021. The median age of participants was 47 and 42 years in Part B and C, respectively, and ∼50% had ≥ 1 risk factor for progression to severe disease. The viral load at baseline and through Day 29 of follow-up for each arm is shown in Table 1 and Figure 1. The primary objective was met for both study parts: the ratio of the least square geometric mean viral load AUC(D1-8) of sotrovimab IM vs IV was 1.04 (90% CI, 0.98, 1.09) and 1.02 (90% CI, 0.94, 1.11), for Part B and C, respectively. Through Day 29 of follow-up, the most common adverse event was injection site reactions (ISRs) in the IM arms. A total of 10 (12%) participants in the 500 mg IM group and 4 (5%) participants in the 250 mg IM group experienced an ISR, all Grade 1. Serious adverse events were uncommon, and related to COVID-19 progression, including one death in the 250 mg IM arm (Table 2). ISRs aside, there were few treatment-related AEs (2/84 IV, 1/82 IM) in Part B, none serious. Conclusion IM administration of sotrovimab 500 mg and 250 mg each demonstrated equivalence to 500 mg sotrovimab IV in viral load assessments. Overall, there were no treatment-related serious AEs and sotrovimab was well tolerated. An 500 mg IM formulation will allow for expanded treatment potential with sotrovimab. Funding Vir/GSK (NCT04779879). Disclosures Anil K. Gupta, MD, Vir Biotechnology: Advisor/Consultant|Vir Biotechnology: Grant/Research Support|Vir Biotechnology: Speaker Moti Ramgopal, MD, FACP, FIDSA, AbbVie: Grant/Research Support|Gilead Sciences Inc.: Advisor/Consultant|Gilead Sciences Inc.: Grant/Research Support|Gilead Sciences Inc.: Honoraria|Gilead Sciences Inc.: Stocks/Bonds|GlaxoSmithKline: Advisor/Consultant|GlaxoSmithKline: Grant/Research Support|GlaxoSmithKline: Honoraria|GlaxoSmithKline: Stocks/Bonds|Janssen Research & Development LLC: Advisor/Consultant|Janssen Research & Development LLC: Grant/Research Support|Janssen Research & Development LLC: Honoraria|Janssen Research & Development LLC: Stocks/Bonds|Merck: Advisor/Consultant|Merck: Grant/Research Support|Merck: Honoraria|Merck: Stocks/Bonds|Shionogi: Grant/Research Support|ViiV: Advisor/Consultant|ViiV: Grant/Research Support Jennifer Han, MD, GlaxoSmithKline: Employee Jennifer Moore, MD, GlaxoSmithKline: Employee Rudrani Banerjee, PhD, GSK: Employee|GSK: Stocks/Bonds Phillip Yates, PhD, GSK: Employee during conduct of this research|GSK: Stocks/Bonds Jill Walker, PhD, GlaxoSmithKline: Employee Gretja Schnell, PhD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Mary Beth Connolly, PharmD, GSK: Employee|GSK: Stocks/Bonds Andrea L. Cathcart, PhD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Varsha Imber, MSc, GSK: Employee|GSK: Stocks/Bonds Rabia Anselm, n/a, GSK: Employee|GSK: Stocks/Bonds Lindsay Winograd, MSc, GSK: Employee|GSK: Stocks/Bonds Nancy Haeusser, n/a, GSK: Employee|GSK: Stocks/Bonds Scott Segal, MD, GSK: Employee|GSK: Stocks/Bonds Andrew Skingsley, MD, GlaxoSmithKline: Employee|GlaxoSmithKline: Stocks/Bonds Melissa Aldinger, PharmD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Amanda Peppercorn, MD, GlaxoSmithKline: Employee|GlaxoSmithKline: Stocks/Bonds.