A randomized, double-blind, placebo-controlled trial of intravenous alpha-1 antitrypsin for ARDS secondary to COVID-19

Abstract

Background: Patients with severe coronavirus disease 2019 (COVID-19) develop a febrile pro-inflammatory cytokinemia with accelerated progression to acute respiratory distress syndrome (ARDS). Here we report the results of a phase 2, multicenter, randomized, double-blind, placebo-controlled trial of intravenous (IV) plasma-purified alpha-1 antitrypsin (AAT) for moderate to severe ARDS secondary to COVID-19 (EudraCT 2020-001391-15).

Methods: Patients (n = 36) were randomized to receive weekly placebo, weekly AAT (Prolastin, Grifols, S.A.; 120 mg/kg), or AAT once followed by weekly placebo. The primary endpoint was the change in plasma interleukin (IL)-6 concentration at 1 week. In addition to assessing safety and tolerability, changes in plasma levels of IL-1β, IL-8, IL-10, and soluble tumor necrosis factor receptor 1 (sTNFR1) and clinical outcomes were assessed as secondary endpoints.

Findings: Treatment with IV AAT resulted in decreased inflammation and was safe and well tolerated. The study met its primary endpoint, with decreased circulating IL-6 concentrations at 1 week in the treatment group. This was in contrast to the placebo group, where IL-6 was increased. Similarly, plasma sTNFR1 was substantially decreased in the treatment group while remaining unchanged in patients receiving placebo. IV AAT did not definitively reduce levels of IL-1β, IL-8, and IL-10. No difference in mortality or ventilator-free days was observed between groups, although a trend toward decreased time on ventilator was observed in AAT-treated patients.

Conclusions: In patients with COVID-19 and moderate to severe ARDS, treatment with IV AAT was safe, feasible, and biochemically efficacious. The data support progression to a phase 3 trial and prompt further investigation of AAT as an anti-inflammatory therapeutic.

Funding: ECSA-2020-009; Elaine Galwey Research Bursary.

Keywords: COVID-19; acute respiratory distress syndrome; alpha-1 antitrypsin; clinical trial; coronavirus; cytokines; inflammation; interleukin-6; randomized control trial.

Graphical abstract

Figure 1

Consort diagram Of 86 consecutive patients screened, 36 underwent randomization having satisfied the criteria for entry to the study. Of the 33 patients included in the primary endpoint analysis (change in circulating interleukin (IL)-6 concentration at 1 week), 22 had received a single infusion of alpha-1 antitrypsin (AAT) (highlighted in red) and 11 had received a single placebo infusion (highlighted in blue). Patients in the AAT treatment group subsequently received either weekly AAT or weekly placebo as part of a pilot safety and feasibility assessment.

Figure 2

Decreased circulating IL-6 following treatment with IV AAT (A) Plasma was obtained at day 0 and day 7 from patients receiving placebo (n = 11) and patients receiving AAT (n = 22). IL-6 levels were increased at day 7 compared with day 0 in the placebo group (day 0, 259.9 ± 206.5 pg/mL; day 7, 348.2 ± 264.0 pg/mL; p = 0.04) and decreased at day 7 in the AAT group (day 0, 296.0 ± 219.7 pg/mL; day 7, 217.7 ± 168.7 pg/mL; p = 0.003). (B) The 7-day change in plasma levels of IL-6 from baseline was +88.3 ± 125.8 pg/mL in the placebo group compared with −78.3 ± 112.1 pg/mL in the treatment group (p = 0.002). (C) Patients assigned to placebo demonstrated a 37.8% ± 56.6% increase in plasma IL-6 at day 7 compared with a mean reduction of 17.4% ± 42.3% in those receiving IV AAT (p = 0.01).

Figure 3

Secondary biochemical endpoints (A) At day 7, levels of soluble tumor necrosis factor receptor 1 (sTNFR1) were not significantly different in the placebo group compared with day 0 (day 0, 3,808 ± 1,989 pg/mL; day 7, 4,315 ± 1,919 pg/mL; p = 0.3), in contrast to the AAT group, where sTNFR1 levels were decreased at day 7 (day 0, 4,947 ± 2,605 pg/mL; day 7, 4,131 ± 2,207 pg/mL; p = 0.0009). (B and C) Compared with placebo, patients receiving AAT demonstrated a greater absolute change (placebo, +507.6 ± 1,552 pg/mL; AAT, −815.8 ± 989.0 pg/mL; p = 0.02) and the percentage change (placebo, +23.1% ± 37.7%; AAT, −15.3% ± 19.6%; p = 0.008) in sTNFR1 at day 7. (D) No difference in IL-1β levels was detected at day 7 in either the placebo group (day 0, 174.7 ± 99.8 pg/mL; day 7, 179.9 ± 94.9 pg/mL; p = 0.98) or the AAT group (day 0, 224.7 ± 177.6 pg/mL; day 7; 164.9 ± 132.7 pg/mL; p = 0.11). (E and F) Treatment with AAT did not result in a greater absolute change (p = 0.32) or percentage change (p = 0.29) at day 7. (G−L) Similarly, no differences were observed for IL-8 on day 0 versus day 7 in either group (placebo, 205.2 ± 131.8 pg/mL versus 218.8 ± 91.3 pg/mL, p = 0.56; AAT, 264.3 ± 193.0 pg/mL versus 198.1 ± 110.1 pg/mL, p = 0.13) or for IL-10 (placebo, 92.1 ± 46.0 pg/mL versus 105.0 ± 42.9 pg/mL, p = 0.28; AAT, 82.3 ± 40.8 versus 76.9 ± 39.4 pg/mL, p = 0.53). For both IL-8 and IL-10, the 7-day change in concentration failed to reach statistical significance, either in absolute (IL-8, p = 0.21; IL-10, p = 0.22) or percentage terms (IL-8, p = 0.08; IL-10, p = 0.13).

Figure 4

Physiological properties of IL-6 are preserved in patients treated with IV AAT (A) Circulating CRP levels were measured in patients receiving IV AAT at study commencement (day 0) and again at 1 week post infusion (day 7, n = 22). CRP was decreased—but not abolished entirely—at day 7 compared with day 0 (day 0, 168.6 ± 138.0 mg/L; day 7, 110.4 ± 117.2 mg/L; p = 0.04). (B) AAT protein phenotypes in plasma from patients in the treatment group (day 7 post infusion; IV AAT) and patients receiving tocilizumab for COVID-19 ARDS (TCZ) were determined by immunofixation of glycoforms via isoelectric focusing gel electrophoresis. Exogenous Prolastin (PRL) was also assayed, to demonstrate an absence of M0/M1 bands in the infused study drug. Endogenous M0/M1 AAT glycoforms were present in patients receiving exogenous IV AAT, but were absent in patients receiving tocilizumab (representative image).