What is the status of interleukin-6 (IL-6) inhibitors in the treatment of coronavirus disease 2019 (COVID-19)?

Updated: Jul 01, 2020
  • Author: Medscape Drugs & Diseases; more...
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IL-6 is a pleiotropic proinflammatory cytokine produced by various cell types, including lymphocytes, monocytes, and fibroblasts. SARS-CoV-2 infection induces a dose-dependent production of IL-6 from bronchial epithelial cells. This cascade of events is the rationale for studying IL-6 inhibitors. As of June 2020, the NIH guidelines note insufficient data to recommend for or against use of IL-6 inhibitors. [34]

On March 16, 2020, Sanofi and Regeneron announced initiation of a phase 2/3 trial of the IL-6 inhibitor sarilumab (Kevzara). The United States–based component of the trial will be initiated in New York. The multicenter, double-blind, phase 2/3 trial has an adaptive design with two parts and is anticipated to enroll up to 400 patients. The first part will recruit patients with severe COVID-19 infection across approximately 16 US sites, and will evaluate the effect of sarilumab on fever and the need for supplemental oxygen. The second, larger, part of the trial will evaluate improvement in longer-term outcomes, including preventing death and reducing the need for mechanical ventilation, supplemental oxygen, and/or hospitalization. [35]

Based on the phase 2 trial analysis, the ongoing phase 3 design was modified on April 27, 2020, to include only higher-dose sarilumab (400 mg) or placebo in critical patients (ie, requiring mechanical ventilation or high-flow oxygenation or ICU admission). In the preliminary phase 2 analysis, sarilumab had no notable benefit on clinical outcomes when combining the severe (ie, required oxygen supplementation) and critical groups versus placebo. However, there were negative trends for most outcomes in the severe group, while there were positive trends for all outcomes in the critical group. [36]

Phase 2 data for critical patients in the 400-mg group (n=145) compared with placebo (n=77), respectively, included the following: [36]

  • Change from baseline C-reactive protein level: -79% versus -21%
  • Died: 23% versus 27%
  • Remained on ventilator: 9% versus 27%
  • Clinical improvement: 59% versus 41%
  • Off oxygenation: 58% versus 41%
  • Discharged: 53% versus 41%

Another IL-6 inhibitor, tocilizumab (Actemra), is part of several randomized, double-blind, placebo-controlled phase 3 clinical trials to evaluate the safety and efficacy of tocilizumab plus standard of care in hospitalized adult patients with severe COVID-19 pneumonia compared to placebo plus standard of care. The REMDACTA study adds tocilizumab to a regimen of remdesivir in hospitalized patients with severe COVID-19 pneumonia. The COVACTA study is nearing enrollment completion to evaluate tocilizumab plus standard of care versus standard of care alone in patients hospitalized with severe COVID-19. In addition, the EMPACTA study will focus on trials in sites known to provide critical care to underserved and minority populations. [37]

A study compared outcomes of patients who received tocilizumab (n = 78) with tocilizumab-untreated controls in patients with COVID-19 requiring mechanical ventilation. Tocilizumab was associated with a 45% reduction in hazard of death (hazard ratio 0.55 [95% CI 0.33, 0.90]) and improved status on the ordinal outcome scale (odds ratio per one-level increase: 0.59 [0.36, 0.95]). Tocilizumab was associated with an increased incidence of superinfections (54% vs 26%; P < 0.001); however, there was no difference in 28-day case fatality rate among tocilizumab-treated patients with superinfection versus those without superinfection (22% vs 15%; P = 0.42). [38]

An observational study in New Jersey showed an improved survival rate among patients who received tocilizumab. Among 547 ICU patients, including 134 receiving tocilizumab in the ICU, an exploratory analysis found a trend toward an improved survival rate of 54% who received tocilizumab compared with 44% who did not receive the therapy and a propensity adjusted hazard ratio of 0.76. [39]

An open label, non-controlled, non–peer reviewed study was conducted in China in 21 patients with severe respiratory symptoms related to COVID-19. All had a confirmatory diagnosis of SARS-CoV-2 infection. The patients in the trial had a mean age of 56.8 years (18 of 21 were male). Although all patients met enrollment criteria of (1) respiratory rate of 30 breaths/min or more, (2) SpO2 of 93% or less, and (3) PaO2/FiO2 of 300 mm Hg or less, only two of the patients required invasive ventilation. The other 19 patients received various forms of oxygen delivery, including nasal cannula, mask, high-flow oxygen, and noninvasive ventilation. All patients received standard of care, including lopinavir and methylprednisolone. Patients received a single dose of 400 mg tocilizumab via intravenous infusion. In general, the patients improved with lower oxygen requirements, lymphocyte counts returned to normal, and 19 patients were discharged with a mean of 15.5 days after tocilizumab treatment. The authors concluded that tocilizumab was an effective treatment in patients with severe COVID-19. [40]

A retrospective review of 25 patients with confirmed severe COVID-19 who received tocilizumab plus investigational antivirals showed patients who received tocilizumab experienced a decline in inflammatory markers, radiological improvement, and reduced ventilatory support requirements. The authors acknowledged the study’s limitations and the need for adequately powered randomized controlled trials of tocilizumab. [41]

Nonetheless, these conclusions should be viewed with extreme caution. No controls were used in this study, and only one patient was receiving invasive mechanical ventilation. In addition, all patients were receiving standard therapy for at least a week before tocilizumab was started. AWP for 400 mg of tocilizumab is $2765.

Another anti-interleukin-6 receptor monoclonal antibody (TZLS-501; Tiziana Life Sciences and Novimmune) is currently under development. [42]

Several studies involving the IL-1 inhibitor anakinra (Kineret) have emerged. A retrospective study in Italy looked at patients with COVID-19 and moderate-to-severe ARDS who were managed with noninvasive ventilation outside of the ICU. The study compared outcomes of patients who received anakinra (5 mg/kg IV BID [high-dose] or 100 mg SC BID [low-dose]) plus standard treatment (ie, hydroxychloroquine 200 mg PO BID and lopinavir/ritonavir 400 mg/100 mg PO BID) with standard of care alone. At 21 days, treatment with high-dose anakinra was associated with reductions in serum C-reactive protein levels and progressive improvements in respiratory function in 21 (72%) of 29 patients; 5 (17%) patients were on mechanical ventilation and 3 (10%) died. In the standard treatment group, 8 (50%) of 16 patients showed respiratory improvement at 21 days; 1 (6%) patient was on mechanical ventilation and 7 (44%) died. At 21 days, survival was 90% in the high-dose anakinra group and 56% in the standard treatment group (P = 0.009). [43]

A study in Paris from March 24 to April 6, 2020, compared outcomes of 52 consecutive patients with COVID-19 who were given anakinra with 44 historical cohort patients. Admission to the ICU for invasive mechanical ventilation or death occurred in 13 (25%) patients in the anakinra group and 32 (73%) patients in the historical group (hazard ratio [HR] 0.22 [95% CI, 0.11-0.41; P < 0.0001). Similar results were observed for death alone (HR 0.30 [95% CI, 0.12-0.71]; P = 0.0063) and need for invasive mechanical ventilation alone (0.22 [0.09-0.56]; P = 0.0015). [44]

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