ABSTRACT
BackgroundCoronavirus disease 2019 (Covid-19) pneumonia is often associated with hyperinflammation. Safety and efficacy of the anti-interleukin-6 receptor antibody tocilizumab was evaluated in patients hospitalized with Covid-19 pneumonia. MethodsNonventilated patients hospitalized with Covid-19 pneumonia were randomized (2:1) to tocilizumab (8 mg/kg intravenous) or placebo plus standard care. Sites enrolling high-risk and minority populations were emphasized. The primary endpoint was cumulative proportion of patients requiring mechanical ventilation or who had died by Day 28. ResultsOf 389 randomized patients, 249 patients received tocilizumab and 128 received placebo in the modified intent-to-treat population (Hispanic/Latino, 56.0%; Black/African American, 14.9%; American Indian/Alaska Native, 12.7%; White, 12.7%; other/unknown, 3.7%). The cumulative proportion (95% confidence interval [CI]) of patients requiring mechanical ventilation or who had died by Day 28 was 12.0% (8.52% to 16.86%) and 19.3 % (13.34% to 27.36%) for the tocilizumab and placebo arms, respectively (log-rank P=0.0360; hazard ratio, 0.56 [95% CI, 0.33 to 0.97]). Median time to clinical failure up to Day 28 favored tocilizumab over placebo (hazard ratio 0.55 [95% CI, 0.33 to 0.93]). All-cause mortality by Day 28 was 10.4% with tocilizumab and 8.6% with placebo (weighted difference, 2.0% [95% CI, - 5.2% to 7.8%). In the safety population, serious adverse events occurred in 15.2% of tocilizumab patients (38/250 patients) and 19.7% of placebo patients (25/127). ConclusionsThis trial demonstrated the efficacy and safety of tocilizumab over placebo in reducing the likelihood of progression to requiring mechanical ventilation or death in nonventilated patients hospitalized with Covid-19 pneumonia. Trial registrationClinicalTrials.gov NCT04372186
ABSTRACT
Severe Acute Respiratory Syndrome - Coronavirus-2 (SARS-CoV-2) infection causes Coronavirus Disease 2019 (COVID-19), a mild to moderate respiratory tract infection in the majority of patients. A subset of patients, however, progresses to severe disease and respiratory failure with acute respiratory distress syndrome (ARDS). Severe COVID-19 has been associated with increased neutrophil counts and dysregulated immune responses. The mechanisms of protective immunity in mild forms and the pathogenesis of dysregulated inflammation in severe courses of COVID-19 remain largely unclear. Here, we combined two single-cell RNA-sequencing technologies and single-cell proteomics in whole blood and peripheral blood mononuclear cells (PBMC) to determine changes in immune cell composition and activation in two independent dual-center patient cohorts (n=46+n=54 COVID-19 samples), each with mild and severe cases of COVID-19. We observed a specific increase of HLA-DRhiCD11chi inflammatory monocytes that displayed a strong interferon (IFN)-stimulated gene signature in patients with mild COVID-19, which was absent in severe disease. Instead, we found evidence of emergency myelopoiesis, marked by the occurrence of immunosuppressive pre-neutrophils and immature neutrophils and populations of dysfunctional and suppressive mature neutrophils, as well as suppressive HLA-DRto monocytes in severe COVID-19. Our study provides detailed insights into systemic immune response to SARS-CoV-2 infection and it reveals profound alterations in the peripheral myeloid cell compartment associated with severe courses of COVID-19.