We aimed to evaluate icatibant, a competitive antagonist of the bradykinin B2 receptors, for the treatment of inpatients with coronavirus disease 2019 (COVID-19) pneumonia admitted in the early hypoxemic stage. The randomized, open-label clinical trial of icatibant for COVID-19 pneumonia (ICAT·COVID, registered as NCT04978051 at ClinicalTrials.gov) was conducted in Barcelona. Inpatients requiring supplemental but not high-flow oxygen or mechanical ventilation were allocated (1:1) to treatment with either three 30-mg icatibant doses/d for 3 consecutive days plus standard care or standard care alone, and followed for up to 28 days after initial discharge. The primary and key secondary outcomes were clinical response on study day 10/discharge and clinical efficacy at 28 days from initial discharge, respectively. Clinical response occurred in 27 of 37 patients (73.0%) in the icatibant group and 20 of 36 patients (55.6%) in the control group (rate difference, 17.42; 95% confidence interval [CI], −4.22 to 39.06; P = .115). Clinical efficacy ensued in 37 patients (100.0%) in the icatibant group and 30 patients (83.3%) in the control group (rate difference, 16.67; 95% CI, 4.49-28.84; P = .011). No patient died in the icatibant group, compared with 6 patients (16.7%) in the control group (P = .011). All patients but 1 had adverse events, which were evenly distributed between study arms. No patient withdrew because of adverse events. Adding icatibant to standard care was safe and improved both COVID-19 pneumonia and mortality in this proof-of-concept study. A larger, phase 3 trial is warranted to establish the clinical value of this treatment. NCT04978051.

Background: COVID-19 has quickly become a global pandemic with a substantial number of deaths and is a considerable burden for healthcare systems worldwide. Although most cases are paucisymptomatic and limited to the viral infection-related symptoms, some patients evolve to a second phase, with an impaired inflammatory response (cytokine storm) that may lead to acute respiratory distress syndrome and death. This is thought to be caused by increased bradykinin synthesis. Methods: ICAT-COVID is a multicenter, randomized, open-label, proof-of-concept phase II clinical trial assessing the clinical efficacy and safety of adding icatibant to the standard of care in patients hospitalized with COVID-19 without invasive mechanical ventilation. Patients hospitalized with a confirmed COVID-19 pneumonia diagnosis (RT-PCR or antigen test ≤ 10 days prior to randomization, and radiographic evidence of pulmonary infiltrates), rated “4” or “5” on the WHO’s clinical status scale, are eligible. Patients will be randomized on a 1:1 ratio to either standard of care-plus-icatibant (experimental group) or to standard of care alone (control group). The experimental group will receive 30 mg of icatibant subcutaneously 3 times a day for 3 days (for a total of 9 doses). The expected sample size is 120 patients (60 per group) from 2 sites in Spain. Primary outcomes are the efficacy and safety of Icatibant. The main efficacy outcome is the number of patients reaching grades “2” or “1” on the WHO scale within 10 days of starting treatment. Secondary outcomes include “long-term efficacy”: number of patients discharged who do not present COVID-19-related relapse or comorbidity up until 28 days after discharge, and mortality. Discussion: Icatibant, a bradykinin type 2 receptor antagonist with proven effectiveness and safety against hereditary angioedema attacks, may be beneficial for COVID-19 patients by inhibiting bradykinin’s action on endothelial cells and by inhibiting the SARS-CoV-2 M protease. Our working hypothesis is that treatment with standard of care-plus-icatibant is effective and safe to treat patients infected with SARS-CoV-2 admitted to hospital for pneumonia without invasive mechanical ventilation. Trial registration: EudraCT 2020-002166-13. ClinicalTrials.gov NCT04978051

We used the data from a successful therapeutic assay that used icatibant in patients with hypoxemic COVID-19 pneumonia (the ICAT·COVID trial) to explore pathophysiological mechanisms. We performed concurrent-type, criterion-related validity analyses to assess the discriminative ability of a panel of nine potential serum markers (interleukin 6, ferritin, lactate dehydrogenase, C reactive protein, fibrin fragment D (D-dimer), complement 1 esterase inhibitor (antigenic and functional), complement 4 factor, and lymphocyte count) to predict the clinical milestones. Consistent with previous research, we evidenced a significant relationship between interleukin 6, lactate dehydrogenase and the lymphocyte count, and the clinical events. Furthermore, exposure to icatibant, a bradykinin B2 receptor antagonist (which improved pneumonia and mortality in the aforementioned randomised trial), attenuated this relationship, although this effect faded over time. The results reinforce the key role that the angiotensin-converting enzyme 2 has on COVID-19 pathophysiology as a point of convergence between the renin–angiotensin and kallikrein–kinin systems. This was shown clinically by the successful blocking of inflammatory pathways by icatibant at the bradykinin effector loop level early during the acute hyperinflammatory stage of the disease.