Search

Background500 mg intravenous (IV) sotrovimab has been shown to be well tolerated and efficacious against pre-Omicron strains in treating patients with mild to moderate coronavirus disease 2019 (COVID-19) at high risk for disease progression.MethodsThis was an open-label, single-arm substudy of phase 3 COMET-TAIL (NCT04913675) assessing the safety and tolerability of a 2000 mg IV dose of sotrovimab. Symptomatic patients (aged ≥18 years) with COVID-19 at high risk for progression were enrolled from June 30 through July 11, 2022, when Omicron BA.5, BA.2.12.1, and BA.4 were the predominant circulating variants in the United States. The primary endpoint was occurrence of adverse events (AEs), serious AEs (SAEs), AEs of special interest, and COVID-19 disease-related events (DREs) through Day 8. Safety, pharmacokinetics, viral load, and hospitalization >24 hours for acute management of illness or death through Day 29 were assessed.ResultsAll participants (n=81) were Hispanic, 58% were female, and 51% were aged ≥55 years. Through Day 8, no AEs, including infusion-related reactions or hypersensitivity, were reported; 2 participants reported DREs (mild cough, n=2). One SAE (acute myocardial infarction), which was considered unrelated to sotrovimab or COVID-19 by the investigator, occurred on Day 27 and was the only hospitalization reported. Maximum serum concentration (geometric mean) was 745.9 µg/mL. Viral load decreased from baseline through Day 29; only 2 participants (3%) had persistently high viral load (≥4.1 log10copies/mL) at Day 8.Conclusions2000 mg IV sotrovimab was well tolerated, with no new unanticipated safety signals observed.Key points summaryIn participants with mild to moderate coronavirus disease 2019 at risk for progression to severe disease, a 2000 mg intravenous dose of sotrovimab had a low frequency of adverse events, with no hypersensitivity, infusion-related reactions, or deaths observed.

Background Sotrovimab is a human monoclonal antibody targeting a conserved region of the SARS-CoV-2 spike (S) protein. COMET-PEAK was a 3-part, phase 2 study that evaluated intravenous (500 mg) and intramuscular (500 mg and 250 mg) administration of sotrovimab in outpatients (n=353) with mild-to-moderate COVID-19. We assessed amino acid substitutions in the SARS-CoV-2 S protein and circulating variants of concern/interest (VOC/VOI) in COMET-PEAK participants (enrolled Feb–July 2021). Methods Mid-turbinate (Part A) or nasopharyngeal (Part B/C) samples were obtained from all participants at Baseline and Post-Baseline visits. Next generation sequencing of the SARS-CoV-2 S gene was conducted using Illumina MiSeq with a ≥5% allelic frequency cut-off for samples with a viral load above 3.0 log10 copies/mL. Baseline, post-baseline and treatment-emergent (TE) substitutions were assessed, and prevalence of VOC/VOI was evaluated. Phenotypic analyses of epitope substitutions were conducted using a pseudotyped virus assay. Results In total, 282/353 participants had sequencing results for ≥1 visit (253 baseline, 248 post-baseline), and 219 had paired baseline and post-baseline sequences; among these, 149 (68%) had TE substitutions in the S protein (26 [12%] in the epitope). E340K was the predominant TE substitution in the epitope (15 [7%]). Across all arms 92/245 (38%) experienced virologic rebound, 8 of whom (Part A: 2; Part B: 2; Part C: 4) had TE substitutions in the epitope; none had evidence of clinical progression to severe disease. Prevalence of VOC/VOI or single amino acid substitutions of concern was 94% (266/282); the most frequent were Alpha (Part A: 8/16 [50%]; Part B: 75/128 [59%]) and Delta (Part C: 99/122 [81%]). Of 7 participants with evidence of clinical progression, none had S protein substitutions in the epitope and all had VOC/VOI (3 Alpha, 3 Delta, 1 Gamma). Sotrovimab effectively neutralized most epitope substitutions tested in vitro; P337L and E340A/K/V conferred significantly reduced susceptibility. Conclusion There was no evidence that sotrovimab epitope substitutions were associated with clinical progression or virologic rebound. These data are consistent with those from the COMET-ICE study. Funding Vir Biotechnology/GSK (NCT04779879). Disclosures Phillip J Yates, PhD, GlaxoSmithKline: Employee Jennifer Moore, MD, GlaxoSmithKline: Employee Jennifer Han, MD, GlaxoSmithKline: Employee Andrew Skingsley, MD, GlaxoSmithKline: Employee|GlaxoSmithKline: Stocks/Bonds Gretja Schnell, PhD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Andrea L. Cathcart, PhD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Melissa Aldinger, PharmD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Amanda Peppercorn, MD, GlaxoSmithKline: Employee|GlaxoSmithKline: Stocks/Bonds Jill Walker, PhD, GlaxoSmithKline: Employee.

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.

Background Sotrovimab (VIR-7831) is an engineered human monoclonal antibody targeting a conserved region of the SARS-CoV-2 spike protein; it has been shown to have a favorable safety profile and be effective for early treatment of high-risk COVID-19 patients. The COMET-TAIL phase 3 study evaluated sotrovimab administered intravenously (IV) or intramuscularly (IM) for the treatment of participants with mild to moderate COVID-19 who are at high risk of disease progression. Methods Between June to August 2021, 973 participants were randomized and received sotrovimab by 500 mg IV infusion or by 500 or 250 mg IM injection. Deep sequencing of the spike gene was performed on nasopharyngeal samples. Baseline (BL; Day 1 or Day 3), post-BL (Day 5 or later), treatment-emergent (TE) substitutions at sotrovimab epitope positions, and presence of variants of concern/interest (VOC/VOI), were evaluated at a ≥5% allelic frequency. Phenotypic analyses were conducted using a pseudotyped virus assay. Results Sequences were available from 764 participants (500 mg IV: 314/393; 500 mg IM: 302/387; 250 mg IM: 148/193). Consistent with VOC circulation during enrollment, the Delta variant was detected in 88.2% (674/764) of participants. Alpha and Mu variants were also seen at >2% prevalence. Of the 764 participants, 26 met the primary endpoint for clinical progression to hospitalization >24 hours or death due to any cause through day 29 and were infected with Delta (500 mg IV: 4; 500 mg IM: 9; 250 mg IM: 11), Alpha (500 mg IM: 1), or Mu (500 mg IV: 1) variants. Substitutions at sotrovimab epitope positions were similar across arms and were detected in 82/764 (10.7%) participants at any visit (500 mg IV: 42/314; 500 mg IM: 27/302; 250 mg IM: 13/148). Of these, 2 participants experienced clinical progression: 1 participant infected with the Mu variant (500 mg IV) carried the characteristic R346K substitution at BL; 1 participant infected with the Delta variant (500 mg IM) had P337L and E340K substitutions detected at Day 3 and P337L was enriched at Day 8. The predominant TE epitope substitutions included P337L and E340A/K/V, which confer reduced susceptibility to sotrovimab in vitro. Conclusion Overall, TE epitope substitutions were not associated with clinical progression. Funding Vir & GSK (NCT04913675) Disclosures Maria L. Agostini, PhD, Vir Biotechnology, Inc: Employee|Vir Biotechnology, Inc: Stocks/Bonds Gretja Schnell, PhD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Julia di Iulio, PharmD, PhD, MBA, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Anita Kohli, MD, GlaxoSmithKline: Third party funding to Vir|Vir Biotechnology Inc: Support as a trial site paid to my institution and non-financial support for medical writing support Adrienne E. Shapiro, MD, PhD, Vir Biotechnology: Support as a trial site paid to my institution and non-financial support for medical writing GlaxoSmithKline third party funding to Vir support Elias H. Sarkis, MD, Abbvie: Grant/Research Support|Abbvie: Speakers Bureau|Eisai: Grant/Research Support|GlaxoSmithKline: Third party funding to Vir|Ironshore: Grant/Research Support|Janssen: Speakers Bureau|Lilly: Grant/Research Support|Otsuka: Grant/Research Support|Teva: Speakers Bureau|Vir Biotechnology Inc: Support as a trial site paid to my institution and non-financial support for medical writing support Dave Inman, MSc, GlaxoSmithKline: Employee|GlaxoSmithKline: Stocks/Bonds Amanda Peppercorn, MD, GlaxoSmithKline: Employee|GlaxoSmithKline: Stocks/Bonds Andrew Skingsley, MD, GlaxoSmithKline: Employee|GlaxoSmithKline: Stocks/Bonds Leah A. Gaffney, PhD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Melissa Aldinger, PharmD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Christy M. Hebner, PhD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds Andrea L. Cathcart, PhD, Vir Biotechnology: Employee|Vir Biotechnology: Stocks/Bonds.

Sotrovimab is a recombinant human monoclonal antibody that has been shown to prevent progression to hospitalization or death from severe disease in non-hospitalized high-risk patients with mild-to-moderate COVID-19 following either intravenous (IV) or intramuscular (IM) administration. Population pharmacokinetic (popPK) and exposure-response (ER) analyses were performed to characterize sotrovimab PK and the relationship between exposure and response (probability of progression), as well as covariates that may contribute to between-participant variability in sotrovimab PK and efficacy following IV or IM administration. Sotrovimab PK was described by a two-compartment model with linear elimination; IM absorption was characterized by a sigmoid absorption model. PopPK covariate analysis led to the addition of the effect of body weight on systemic clearance and peripheral volume of distribution, sex on IM bioavailability and first-order absorption rate (KA), and body mass index on KA. However, the magnitude of covariate effect was not pronounced and was therefore not expected to be clinically relevant based on available data to date. For ER analysis, sotrovimab exposure measures were predicted using the final popPK model. An ER model was developed using the exposure measure of sotrovimab concentration at 168 hours that described the relationship between exposure and probability of progression within the ER dataset for COMET-TAIL. The number of risk factors (≤1 vs >1) was incorporated as an additive shift on the model-estimated placebo response but had no impact on overall drug response. Limitations in the ER model may prevent generalization of these results to describe the sotrovimab exposure-progression relationship across SARS-COV-2 variants.

IMPORTANCE: Older patients and those with comorbidities who are infected with SARS-CoV-2 may be at increased risk of hospitalization and death. Sotrovimab is a neutralizing antibody for the treatment of high-risk patients to prevent COVID-19 progression. OBJECTIVE: To evaluate the efficacy and adverse events of sotrovimab in preventing progression of mild to moderate COVID-19 to severe disease. DESIGN, SETTING, AND PARTICIPANTS: Randomized clinical trial including 1057 nonhospitalized patients with symptomatic, mild to moderate COVID-19 and at least 1 risk factor for progression conducted at 57 sites in Brazil, Canada, Peru, Spain, and the US from August 27, 2020, through March 11, 2021; follow-up data were collected through April 8, 2021. INTERVENTIONS: Patients were randomized (1:1) to an intravenous infusion with 500 mg of sotrovimab (n = 528) or placebo (n = 529). MAIN OUTCOMES AND MEASURES: The primary outcome was the proportion of patients with COVID-19 progression through day 29 (all-cause hospitalization lasting >24 hours for acute illness management or death); 5 secondary outcomes were tested in hierarchal order, including a composite of all-cause emergency department (ED) visit, hospitalization of any duration for acute illness management, or death through day 29 and progression to severe or critical respiratory COVID-19 requiring supplemental oxygen or mechanical ventilation. RESULTS: Enrollment was stopped early for efficacy at the prespecified interim analysis. Among 1057 patients randomized (median age, 53 years [IQR, 42-62], 20% were ≥65 years of age, and 65% Latinx), the median duration of follow-up was 103 days for sotrovimab and 102 days for placebo. All-cause hospitalization lasting longer than 24 hours or death was significantly reduced with sotrovimab (6/528 [1%]) vs placebo (30/529 [6%]) (adjusted relative risk [RR], 0.21 [95% CI, 0.09 to 0.50]; absolute difference, –4.53% [95% CI, –6.70% to –2.37%]; P

Understanding who is at risk of progression to severe COVID-19 is key to effective treatment. We studied correlates of disease severity in the COMET-ICE clinical trial that randomized 1:1 to placebo or to sotrovimab, a monoclonal antibody for the treatment of SARS-CoV-2 infection. Several laboratory parameters identified study participants at greater risk of severe disease, including a high neutrophil-lymphocyte ratio (NLR), a negative SARS-CoV-2 serologic test and whole blood transcriptome profiles. Sotrovimab treatment in these groups was associated with normalization of NLR and the transcriptomic profile, and with a decrease of viral RNA in nasopharyngeal samples. Transcriptomics provided the most sensitive detection of participants who would go on to be hospitalized or die. To facilitate timely measurement, we identified a 10-gene signature with similar predictive accuracy. In summary, we identified markers of risk for disease progression and demonstrated that normalization of these parameters occurs with antibody treatment of established infection.

ImportanceOlder patients and those with underlying comorbidities infected with SARS-CoV-2 may be at increased risk of hospitalization and death from COVID-19. Sotrovimab is a neutralizing antibody designed for treatment of high-risk patients to prevent COVID-19 progression.ObjectiveTo evaluate the efficacy and safety of sotrovimab in preventing progression of mild to moderate COVID-19 to severe disease.DesignRandomized, double-blind, multicenter, placebo-controlled, phase 3 study.Setting57 centers in 5 countries.ParticipantsNonhospitalized patients with symptomatic, mild to moderate COVID-19 and at least 1 risk factor for disease progression.InterventionPatients were randomized (1:1) to an intravenous infusion of sotrovimab 500 mg or placebo.Main Outcomes and MeasuresThe primary efficacy outcome was the proportion of patients with COVID-19 progression, defined as all-cause hospitalization longer than 24 hours for acute illness management or death through day 29. Key secondary outcomes included the proportion of patients with COVID-19 progression, defined as emergency room visit, hospitalization of any duration, or death, and proportion of patients developing severe/critical respiratory COVID-19 requiring supplemental oxygen.ResultsAmong 1057 patients randomized (sotrovimab, 528; placebo, 529), all-cause hospitalization longer than 24 hours or death was significantly reduced with sotrovimab (6/528 [1%]) vs placebo (30/529 [6%]) by 79% (95% CI, 50% to 91%; PPP=.002). No patients receiving sotrovimab required high-flow oxygen, oxygen via nonrebreather mask, or mechanical ventilation compared with 14 patients receiving placebo. The proportion of patients reporting adverse events was similar between treatment groups; sotrovimab was well tolerated, and no safety concerns were identified.Conclusions and RelevanceAmong nonhospitalized patients with mild to moderate COVID-19, a single 500-mg intravenous dose of sotrovimab prevented progression of COVID-19, with a reduction in hospitalization and need for supplemental oxygen. Sotrovimab is a well-tolerated, effective treatment option for patients at high risk for severe morbidity and mortality from COVID-19.Trial RegistrationClinicalTrials.gov Identifier: NCT04545060

Coronavirus disease 2019 (Covid-19) disproportionately results in hospitalization or death in older patients and those with underlying conditions. Sotrovimab is a pan-sarbecovirus monoclonal antibody that was designed to prevent progression of Covid-19 in high-risk patients early in the course of disease.In this ongoing, multicenter, double-blind, phase 3 trial, we randomly assigned, in a 1:1 ratio, nonhospitalized patients with symptomatic Covid-19 (≤5 days after the onset of symptoms) and at least one risk factor for disease progression to receive a single infusion of sotrovimab at a dose of 500 mg or placebo. The primary efficacy outcome was hospitalization (for24 hours) for any cause or death within 29 days after randomization.In this prespecified interim analysis, which included an intention-to-treat population of 583 patients (291 in the sotrovimab group and 292 in the placebo group), 3 patients (1%) in the sotrovimab group, as compared with 21 patients (7%) in the placebo group, had disease progression leading to hospitalization or death (relative risk reduction, 85%; 97.24% confidence interval, 44 to 96; P = 0.002). In the placebo group, 5 patients were admitted to the intensive care unit, including 1 who died by day 29. Safety was assessed in 868 patients (430 in the sotrovimab group and 438 in the placebo group). Adverse events were reported by 17% of the patients in the sotrovimab group and 19% of those in the placebo group; serious adverse events were less common with sotrovimab than with placebo (in 2% and 6% of the patients, respectively).Among high-risk patients with mild-to-moderate Covid-19, sotrovimab reduced the risk of disease progression. No safety signals were identified. (Funded by Vir Biotechnology and GlaxoSmithKline; COMET-ICE ClinicalTrials.gov number, NCT04545060.).

BackgroundCoronavirus disease 2019 (Covid-19) disproportionately results in hospitalization and death in older patients and those with underlying comorbidities. Sotrovimab is a pan-sarbecovirus monoclonal antibody designed to treat such high-risk patients early in the course of disease, thereby preventing Covid-19 progression.MethodsIn this ongoing, multicenter, double-blind, phase 3 trial, nonhospitalized patients with symptomatic Covid-19 and at least one risk factor for disease progression were randomized (1:1) to an intravenous infusion of sotrovimab 500 mg or placebo. The primary efficacy endpoint was the proportion of patients with Covid-19 progression, defined as hospitalization longer than 24 hours or death, through day 29.ResultsIn this preplanned interim analysis, which included an intent-to-treat population of 583 patients (sotrovimab, 291; placebo, 292), the primary efficacy endpoint was met. The risk of Covid-19 progression was significantly reduced by 85% (97.24% confidence interval, 44% to 96%; P = 0.002) with a total of three (1%) patients progressing to the primary endpoint in the sotrovimab group versus 21 (7%) patients in the placebo group. All five patients admitted to intensive care, including one who died by day 29, received placebo. Safety was assessed in 868 patients (sotrovimab, 430; placebo, 438). Adverse events were reported by 17% and 19% of patients receiving sotrovimab and placebo, respectively; serious adverse events were less common with sotrovimab (2%) versus placebo (6%).ConclusionSotrovimab reduced progression of Covid-19 in patients with mild/moderate disease, was well tolerated, and no safety signals were identified.Funded by Vir Biotechnology, Inc. and GlaxoSmithKline; ClinicalTrials.govNCT04545060

Understanding who is at risk of progression to severe coronavirus disease 2019 (COVID-19) is key to clinical decision making and effective treatment. We study correlates of disease severity in the COMET-ICE clinical trial that randomized 1:1 to placebo or to sotrovimab, a monoclonal antibody for the treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (ClinicalTrials.gov04545060). Laboratory parameters identify study participants at greater risk of severe disease, including a high neutrophil-to-lymphocyte ratio (NLR), a negative SARS-CoV-2 serologic test, and whole-blood transcriptome profiles. Sotrovimab treatment is associated with normalization of NLR and the transcriptomic profile and with a decrease of viral RNA in nasopharyngeal samples. Transcriptomics provides the most sensitive detection of participants who would go on to be hospitalized or die. To facilitate timely measurement, we identify a 10-gene signature with similar predictive accuracy. We identify markers of risk for disease progression and demonstrate that normalization of these parameters occurs with antibody treatment of established infection.

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)

Background: For children with AL candidate to receive an allograft and lacking a suitable HLA-matched donor, HLA-haplo-HSCT after abTCD may represent a valid alternative. Due to delayed recovery of adaptive T-cell immunity with abTCD-haplo-HSCT alone, we conducted a phase I/II trial testing the safety and efficacy of post-transplant infusion of a titrated number of donor-derived T cells transduced with the iC9 gene (rivogenlecleucel; ClinicalTrials.gov id: NCT02065869) in children with malignant and non-malignant diseases. Here, we report on the cohort of 70 patients with AL treated in Italy with abTCD-haplo-HSCT+rivogenlecleucel, comparing the results with those of 88 patients given abTCD-haplo-HSCT alone and previously published by our group (Blood 2018; 132:2594-2607). Patients and methods: Patients (age < 18 years) were transplanted between 2010 and 2018. Patient and disease characteristics are shown in Table 1. Median age at HSCT was 6 years (range 0.3-18), and median follow-up was 71 and 31 months for abTCD-haplo-HSCT and abTCD-haplo-HSCT+rivogenlecleucel, respectively. Compared to the control group, abTCD-haplo-HSCT+rivogenlecleucel recipients were transplanted more recently and from a younger donor, and received a higher number of CD34+ cells (Table 1). Diagnosis did not differ between the 2 groups, acute lymphoblastic leukemia (ALL) being the most frequent diagnosis. All patients were transplanted in morphological complete remission (CR1 and CR2) and received myeloablative preparation. Graft composition is reported in Table 1; notably all patients received >10x106 CD34+cells/Kg and Results: Graft failure occurred in 2% of patients in each group. Median time to neutrophil and platelet engraftment was 14 (6-23) and 11 (5-56) days, with no differences between groups (p=0.28). Rivogenlecleucel were infused at a median time of 21 days (range 11-59). Treatment was well tolerated; no infusion-related side effects were recorded. Cumulative incidence (CI) of 100-day grade II-IV acute GvHD was 18.9% vs 15.9% (p=0.77) and CI of 1-year chronic GvHD was 6.9% vs 5.7% (p=0.56) in abTCD-haplo-HSCT and abTCD-haplo-HSCT+rivogenlecleucel, respectively. The 4-year non-relapse-mortality (NRM) was significantly lower in abTCD-haplo-HSCT+rivogenlecleucel (1.4% vs 8%, p=0.05) (Figure 1). There was no statistically significant difference in the 4-year CI of relapse (RI) (17% vs. 25%, p=0.30), respectively. Disease recurrence was the most common causes of death in both groups, viral and fungal infections being the most frequent non-relapse fatalities. The 4-year overall survival (OS) and leukemia-free survival (LFS) was 70% vs 87%, p=0.01 (Figure 2) and 67% vs 82%, p=0.05, for abTCD-haplo-HSCT and abTCD-haplo-HSCT+rivogenlecleucel, respectively. There was no difference in 4-year CI of CMV reactivation between the 2 groups (p=0.68), median time to CMV reactivation being 29 and 30 days (p=0.29), respectively. Once infused, rivogenlecleucel expanded (mainly in the CD8+ subset), reaching a peak at 9 months after infusion. At 6-months, median CD3+, CD3/CD4, CD3/CD8, CD3-/CD56 and CD20/CD19 count/microL were 820, 265, 225, 141, 171, for abTCD-haplo-HSCT and 898, 294, 288, 214, and 161 for abTCD-haplo-HSCT+rivogenlecleucel, (p=ns, p=ns, p=0.02, p=0.03, p=ns), respectively. The advantage in the recovery of CD3/CD8 and CD3-/CD56 after abTCD-haplo-HSCT+rivogenlecleucel persisted at 1 year (p=0.01, p=0.03, respectively). In multivariable analysis, abTCD-haplo-HSCT+rivogenlecleucel was associated with better OS (HR 0.27, p=0.003) and LFS (HR 0.40, p=0.001); there was also a trend for lower relapse risk (HR 0.50, p=0.098). Age below the median value at HSCT (HR 2.62, p=0.01), CR1 at HSCT (HR 0.35, p=0.03) and use of irradiation in the conditioning regimen (HR 0.32, p=0.02) were other factors correlating with OS and LFS. Conclusions: These data confirm that the infusion of donor-derived rivogenlecleucel is safe and well tolerated. Rivogenlecleucel cells infusion contributed to enhance recovery of cytotoxic T and NK cells, improving patients NRM and OS/LFS. Rivogenlecleucel (with the possibility of inducing apoptosis of donor T cells) may facilitate the cellular therapy approaches aimed at optimizing immune recovery after HSCT. Disclosures Merli: Amgen: Honoraria; Bellicum: Consultancy; Novartis: Honoraria; Sobi: Consultancy. Algeri:Bluebird bio: Consultancy, Honoraria; Miltenyi: Honoraria; Atara Biotherapeutics: Consultancy, Honoraria. Woodard:Bellicum Pharmaceuticals, Inc: Employment, Other: Stock, Stock options. Locatelli:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BluebirdBio: Consultancy.

Background Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) constitutes a curative treatment for children with malignant and non-malignant disorders. HLA-partially matched haploidentical (haplo) donors represent a viable alternative option for those children who lack an HLA-compatible donor. T-cell depletion approaches with positive (CD34 selection) or negative selection (alpha/beta T-cell and CD19+ B-cell-depletion) may allow engraftment of donor cells with a low risk of GvHD; however, success is limited by delayed immune recovery, increasing the risk of fatal infections. Infusion of unmanipulated donor T cells (DLI) to accelerate immune recovery is associated with high risk of fatal GVHD. In contrast, adoptive transfer of donor T cells genetically manipulated to include a safety switch can be a suitable strategy to render DLI safer and more widely applicable. BPX-501 is an allogeneic product consisting of T cells modified to express the inducible caspase-9 (iC9) safety switch. The polyclonal natural of these modified T cells can provide viral immunity following stem cell transplant, with the unique ability to promptly and durably resolve GvHD symptoms following the administration of rimiducid, an inert, lipid-permeable compound that rapidly induces dimerization and activation of iC9, inducing apoptosis of the gene modified T cells. Aims To evaluate the safety and efficacy of rimiducid in the treatment of GvHD following administration of BPX-501 T cells in pediatric patients with malignant or non-malignant disorders given an αβ T-cell receptor and B-cell depleted haplo-HSCT. A key objective of this study is to assess the activity of rimiducid infusion following onset of GvHD which is refractory to standard of care therapies. Methods Two multicenter (US [NCT03301168] and EU [NCT02065869]), prospective trials utilized αβ-T-cell and B-cell-depleted haplo-HSCT followed by infusion of a titrated number of donor lymphocytes genetically modified with iC9 (BPX-501 T cells) in patients with malignant or non-malignant disorders. BPX-501 T-cells were planned to be infused on day14+/-4 after the allograft. No post-transplant pharmacological GvHD prophylaxis was employed. Patients who develop GvHD resistant to conventional steroid therapy could receive ≥1 dose of dimerizing rimiducid to activate the iC9 safety gene. The efficacy evaluable population is defined as any patient who received ≥ 1 dose of rimiducid for the treatment of GvHD and had a follow up response assessment. Results At the time of clinical cut-off (June 30th, 2018) 249 patients with a malignant (41.4%) or non-malignant disorder (58.6%) were enrolled. The conditioning regimens varied according to the original disease and were Treosulfan-based (14.9%), Busulfan-based (28.9%), TBI-based (34.9%) or other (19.3%). The donor was a parent in 229 children (92 %), a sibling in 17 (6.8 %), and a half-sibling in the remaining 3 (1.2 %). The median time to BPX-501 infusion was 18 days (10 - 66 days). Fifty-two patients developed Grade I-IV aGvHD (cumulative incidence [CI] 21.9 % [95% confidence interval (CoI): 16.7 - 27.2]). Twenty-six patients developed Grade II-IV aGvHD (CI 10.9 %). Five patients developed Grade III-IV aGvHD (CI 2.1 %). Eight patients developed cGvHD (CI of 4.6% [95% CoI: 1.3 - 7.8]). Twenty-one patients met the rimiducid efficacy evaluable population definition. An overall clinical response rate of 86% was observed. A CR or PR to rimiducid was observed in 12 and 6 patients, respectively. Median time to initial response was 2 days (1-61 days). Median number of doses received was 1 (1 - 2). At a median follow-up of 7.8 months (2.3 - 30.8 months), 77% of the initial responders were still in either complete (n=8) or partial response (n=6). Conclusion These data suggest that administration of rimiducid for treatment of steroid-refractory GvHD represents a novel and highly effective treatment approach in pediatric patients with non-malignant or malignant disorders who received a αβ-T-cell and B-cell depleted haplo-HSCT followed by infusion of BPX-501 cells. The administration of rimiducid in children given BPX-501 T cells allows for effective control of GvHD occurring after the adoptive transfer of genetically modified T cells. Disclosures Slatter: Medac: Other: Travel assistance. Merli:Neovii Biotech: Honoraria; AMGEN: Honoraria. Aldinger:Bellicum Pharmaceuticals, Inc.: Employment. Locatelli:Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy.

Background Allogeneic hematopoietic stem cell transplantation (HSCT) has been shown to rescue trilineage cytopenias and to prevent occurrence of myeloid malignancies in patients with Fanconi Anemia (FA). HLA-identical family donor HSCT is a recommended treatment strategy with an ≥80% cure rate, and outcomes of HSCT from unrelated donors have progressively improved over time. However, HLA-partially matched (haplo) HSCTs have been historically associated with inferior results. Innovative approaches of graft manipulation, such as selective depletion of αβ-T and B cells, have recently been reported to improve the outcomes of haplo-HSCT in children with non-malignant disorders, however obstacles remain, such as delayed recovery of adaptive immunity with a risk of life-threatening infections. Novel strategies aimed at accelerating immune reconstitution are warranted to optimize the outcomes of patients transplanted from a HLA-haploidentical family donor. BPX-501 is an allogeneic product consisting of T cells modified to express the inducible caspase-9 (iC9) safety switch and truncated CD19 to allow monitoring and expansion of BPX-501 following transplant. The polyclonal nature of the BPX-501 provides broad virus and tumor-specific immunity, while the safety switch provides the unique ability to promptly and durably resolve graft-versus-host disease (GvHD) symptoms following the administration of rimiducid which induces dimerization and activation of iC9, inducing apoptosis of BPX-501. Aims To evaluate the safety and efficacy (acceleration of immune recovery and prevention of transplant-related mortality while maintaining low rates of acute and chronic GvHD) of BPX-501 administered after a αβ T and B-cell depleted haplo-HSCT in pediatric patients with FA. Methods This is a multicenter US (NCT03301168) and EU (NCT02065869), prospective trial utilizing αβ-T- and B-cell-depleted haplo-HSCT followed by infusion of donor lymphocytes genetically modified to express iC9 (BPX-501 T cells). BPX-501 cells were planned to be infused on day14±4 after the allograft per protocol. No post-transplant pharmacological GvHD prophylaxis was employed. Patients who develop GvHD resistant to conventional steroid therapy were eligible to receive ≥1 dose of dimerizing rimiducid activating iC9. The efficacy-evaluable population (EEP) was defined as any patient with FA who received HSCT, BPX-501 infusion and had at least one follow-up assessment. Results At the time of clinical cut-off (June 30th, 2018), 14 patients met the EEP definition. Nine and 5 patients were transplanted in the EU and US, respectively. The median follow-up was 23.5 mos (0.75 - 42 mos). Key baseline and transplant characteristics are detailed in Table 1. The median time for neutrophil and platelet engraftment was 14 (11-15) and 10 (8 - 11) days, respectively. One patient experienced primary graft failure (7.7% [95% CI: 0-22.2%]). Only one patient developed Grade I aGvHD (7.7% [95% CI: 0-22.2%]). Two patients developed cGvHD (19.2% [95% CI: 4-43.2%]), both cases being moderate. Rimiducid was not administered to any patient. One patient died after transplantation due to brain hemorrhage 25 days post HSCT. The event was unrelated to BPX-501 (TRM 7.1% [95% CI: 0-20.6%]). No patients died of infectious complications. The probability of both overall survival (OS) and disease-free survival (DFS) was 92.9% (95% CI: 79.4-100%). The median time from last red blood cell (RBC) transfusion was 23.6 mos (0.2 - 41.9 mos). CD3+ and CD3+CD4+ T cells above 500 cells/ml were achieved by 180 and 360 days, respectively. IgA and IgM levels achieved normal values by 30 and 180 days, respectively. The percentage of circulating and median absolute BPX-501 cells at Day 100 were 3.35% ± 2.94% (0 - 8.4%) and 29.09 ± 39.56 cells/ml (0 - 135 cells/ml), respectively. Conclusion These data indicate that the adoptive transfer of BPX-501 following αβ-T and B-cell depleted haplo-HSCT represents a novel and highly effective transplantation strategy for pediatric patients with FA. Further, despite the addition of BPX-501, low rates and severity of both acute and chronic GvHD was observed, a finding that could translate into significant long-term benefit, in terms of reduction of squamous cell carcinoma a well-known complication occurring in FA patients after HSCT. Disclosures Aldinger: Bellicum Pharmaceuticals, Inc.: Employment. Locatelli:Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Background: Adoptive transfer of allogeneic donor T cells can be an effective treatment for hematological malignancies through recognition of leukemia-associated antigens (LAAs) on tumor cells or through alloreactivity. However, alloreactive T cells can also cause graft-versus-host disease (GvHD) limiting their use as an immunotherapy. To leverage the anti-tumor effects of allogeneic polyclonal T cells while minimizing GvHD, we have genetically modified donor T cells with the inducible caspase-9 (iC9) safety switch, which induces apoptosis following exposure to the small molecule ligand rimiducid. Here we show that iC9-modified allogeneic T cells (BPX-501) persist, expand and contain functional LAA-specific T cells in children receiving an alpha/beta TCR and CD19-depleted HLA-haploidentical hematopoietic stem cell transplant (haplo-HSCT) for the treatment of myeloid malignancies. Methods: Pre-infusion products (BPX-501: donor T cells modified with the bicistronic retroviral vector encoding iC9 and truncated CD19 (ΔCD19)) and patient peripheral blood mononuclear cells (PBMCs) were analyzed from twelve patients (AML (10), MDS (1), JMML (1)) receiving BPX-501 (1x106 cells/kg) following an alpha/beta T cell and CD19 B cell-depleted haplo-HSCT (BP-004U: NCT03301168). Engraftment and persistence were measured by coexpression of CD3 and CD19 by flow-cytometry. Endogenous and gene-modified T cells were also phenotyped for CD4:CD8 ratios, memory cell composition (TN, TCM, TEM, TEMRA; CD45RA and CD62L) and T cell receptor Vβ diversity. BPX-501 products and post-treatment samples were characterized for LAA-specific T cells using IFN-γ ELISpot against peptide pools (15 aa overlapping by 5 aa) derived from WT1, PRAME, MAGE (A1, C1, C3), NE and PR3, with and without exposure to 10 nM rimiducid to determine the anti-leukemic contribution of BPX-501. Results: BPX-501 was infused at a median time of 22.5 days after HSCT (range 12-34, one patient was infused at day 89 and one patient was infused at day 147). BPX-501 cells (CD3+CD19+) were detectable in the peripheral blood at 1-2 weeks after infusion in all 12 patients, reaching a peak expansion frequency of a median of 24% ± 17% of total CD3+ T cells, and an absolute cell number of 66.9 ± 112 cells/µl at 2 months post-infusion and could be detected for up to 24 months. BPX-501 T cells showed a CD8-skewed phenotype whereas endogenous T cells exhibited a more balanced CD4:CD8 ratio. BPX-501 were predominantly CD45RA-CD62L+ and CD45RA-CD62L- central and effector memory T cells, respectively. In BPX-501 products, we detected LAA-specific T cells by ELISpot using overlapping peptide pools to WT1, PRAME, MAGE, NE and PR3, and in peripheral blood samples obtained 2 to 5 months post-T cell infusion. Importantly, LAA-reactivity was greatly diminished with exposure to iC9-activating rimiducid. Further, we measured the TCR Vβ usage and observed highly-skewed TCR repertoire in BPX-501 T cells compared to endogenous T cells in 6 months after HSCT indicating selection and expansion of TCR clones. Three patients engrafted BPX-501 were treated with rimiducid to control GvHD resulting in a rapid decrease (62% ± 12%) of CD3+CD19+ T cells in the peripheral blood. In patients treated with rimiducid, CD3+CD19+ T cells recover without further instances of GvHD suggestive of in vivo depletion of alloreactive T cell clones using iC9. Summary: Allogeneic T cells engineered with the iC9 safety switch engraft, expand and demonstrate long-term persistence following adoptive transfer into patients receiving a haplo-HSCT. LAA-specific T cells and alloreactive T cells within the BPX-501 product are detectable in the peripheral blood following infusion and likely contribute to elimination of myeloid malignancies. Disclosures Shaw: Bellicum Pharmaceuticals: Employment, Equity Ownership. Zhou:Bellicum Pharmaceuticals: Employment, Equity Ownership. Lu:Bellicum Pharmaceuticals: Employment, Equity Ownership. Aldinger:Bellicum Pharmaceuticals, Inc.: Employment. Spencer:Bellicum Pharmaceuticals: Employment, Equity Ownership. Locatelli:Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; bluebird bio: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Foster:Bellicum: Employment, Equity Ownership.