Fibrinolytic Therapy to Treat ARDS in the Setting of COVID-19 Infection
Condition: Severe Acute Respiratory Syndrome; Respiratory Failure; Acute Respiratory Distress Syndrome
MeSH terms: Severe Acute Respiratory Syndrome; Respiratory Distress Syndrome; Respiratory Distress Syndrome, Newborn; Respiratory Insufficiency; Acute Lung Injury; Syndrome
Study type: Interventional
Phase: Phase 2

Summary: 
      The global pandemic COVID-19 has overwhelmed the medical capacity to accommodate a large
      surge of patients with acute respiratory distress syndrome (ARDS). In the United States, the
      number of cases of COVID-19 ARDS is projected to exceed the number of available ventilators.
      Reports from China and Italy indicate that 22-64% of critically ill COVID-19 patients with
      ARDS will die. ARDS currently has no evidence-based treatments other than low tidal
      ventilation to limit mechanical stress on the lung and prone positioning. A new therapeutic
      approach capable of rapidly treating and attenuating ARDS secondary to COVID-19 is urgently
      needed.

      The dominant pathologic feature of viral-induced ARDS is fibrin accumulation in the
      microvasculature and airspaces. Substantial preclinical work suggests antifibrinolytic
      therapy attenuates infection provoked ARDS. In 2001, a phase I trial 7 demonstrated the
      urokinase and streptokinase were effective in patients with terminal ARDS, markedly improving
      oxygen delivery and reducing an expected mortality in that specific patient cohort from 100%
      to 70%. A more contemporary approach to thrombolytic therapy is tissue plasminogen activator
      (tPA) due to its higher efficacy of clot lysis with comparable bleeding risk 8. We therefore
      propose a phase IIa clinical trial with two intravenous (IV) tPA treatment arms and a control
      arm to test the efficacy and safety of IV tPA in improving respiratory function and
      oxygenation, and consequently, successful extubation, duration of mechanical ventilation and
      survival.
    

Detailed description: 
      As the COVID-19 pandemic accelerates, cases have grown exponentially around the world. Other
      countries' experience suggests that 5-16% of COVID-19 in-patients will undergo prolonged
      intensive care with 50-70% needing mechanical ventilation(MV) threatening to overwhelm
      hospital capacity. ARDS has no effective treatment besides supportive care, the use of
      ventilation strategies encompassing low tidal volumes that limit trans-pulmonary pressures,
      and prone positioning in severe disease. Most current trials in clinicaltrials.gov for
      COVID-19-induced ARDS aim at modulating the inflammatory response or test anti-viral drugs.
      Sarilumab and tocilizumab that block IL-6 effects are being tested in RCT for patients
      hospitalized with severe COVID-19 (NCT04317092, NCT04322773, NCT04327388). The World Health
      Organization international trial SOLIDARITY will test remdesivir; chloroquine +
      hydroxychloroquine; lopinavir + ritonavir; and lopinavir + ritonavir and interferon-beta
      (NCT04321616). Yet studies targeting the coagulation system, which is intrinsically
      intertwined with the inflammatory response are lacking.

      A consistent finding in ARDS is the deposition of fibrin in the airspaces and lung
      parenchyma, along with fibrin-platelet microthrombi in the pulmonary vasculature, which
      contribute to the development of progressive respiratory dysfunction and right heart failure.
      Similar to pathologic findings of ARDS, microthrombi have now been observed in lung specimens
      from patients infected with COVID-19.

      Inappropriate activation of the clotting system in ARDS results from enhanced activation and
      propagation of clot formation as well as suppression of fibrinolysis. Our group has shown
      that low fibrinolysis is associated with ARDS. Studies starting decades ago have demonstrated
      the systemic and local effects of dysfunctional coagulation in ARDS, specifically related to
      fibrin. This occurs largely because of excessive amounts of tissue factor that is produced by
      alveolar epithelial cells and activated alveolar macrophages, and high levels of plasminogen
      activator inhibitor-1 (PAI-1) produced and released by endothelial cells. Consistent with
      this, generalized derangements of the hemostatic system with prolongation of the prothrombin
      time, elevated D-dimer and fibrin degradation products have been reported in severely ill
      COVID-19 patients, particularly in non-survivors. These laboratory findings, in combination
      with the large clot burden seen in the pulmonary microvasculature, mirrors what is seen in
      human sepsis, experimental endotoxemia, and massive tissue trauma. Targeting the coagulation
      and fibrinolytic systems to improve the treatment of ARDS has been proposed for at least the
      past two decades. In particular, the use of plasminogen activators to limit ARDS progression
      and reduce ARDS-induced death has received strong support from animal models, and a phase 1
      human clinical trial. In 2001, Hardaway and colleagues showed that administration of either
      urokinase or streptokinase to patients with terminal ARDS reduced the expected mortality from
      100% to 70% with no adverse bleeding events. Importantly, the majority of patients who
      ultimately succumbed died from renal or hepatic failure, rather than pulmonary failure.

      Consideration of therapies that are widely available but not recognized for this indication
      and traditionally considered "high-risk" such as fibrinolytic agents is warranted in this
      unprecedented public health emergency, since the risk of adverse events from tPA is far
      outweighed by the extremely high risk of death in the patient's meeting the eligibility
      criteria for this trial. While the prior studies by Hardaway et al evaluating fibrinolytic
      therapy for treatment of ARDS used urokinase and streptokinase, the more contemporary
      approach to thrombolytic therapy involves the use of tissue-type plasminogen activator (tPA)
      due to higher efficacy of clot lysis with comparable bleeding risk to the other fibrinolytic
      agents.
    

Intervention name(s): Alteplase 50 MG [Activase]; Alteplase 50 MG [Activase]
Intervention type(s): Drug; Drug
Intervention description(s): Patients randomized to Alteplase-50 group will receive 50 mg of Alteplase intravenous bolus administration over 2 hours, given as a 10 mg push followed by the remaining 40 mgs over a total time of 2 hrs. Immediately following the Alteplase infusion, 5000 units (U) of unfractionated heparin (UFH) will be delivered and the heparin drip will be continued to maintain the activated partial thromboplastin time (aPTT) at 60-80sec (2.0 to 2.5 times the upper limit of normal). Re-bolusing of Alteplase, at the same dose, is permitted in the Alteplase-50 intervention group in those patients who show an initial transient response (>20% improvement of PaO2/FiO2 over pre-infusion of Alteplase at any of the measurements at 2, 6, 12 or 18 hours, but <50% improvement of PaO2/FiO2 at 24 hours after randomization); the repeat dose will be given between 24 and 36 hours after the initial Alteplase administration.; wed by the remaining 40 mgs over a total time of 2 hrs. Immediately following this initial Alteplase infusion, we will initiate a drip of 2 mg/hr Alteplase over the ensuing 24 hours (total 48 mg infusion) accompanied by an infusion of 500 units per hour (U/hr) heparin during the Alteplase drip. After this, heparin dose will be increased slowly to maintain aPTT between 60 and 80 sec, titrated per attending's discretion.
Intervention MeSH terms: Tissue Plasminogen Activator
Allocation: Randomized
Intervention model: Sequential Assignment
Intervention model description: This is a Phase IIa clinical trial, open label, with a modified stepped-wedge design, testing systemic administration of fibrinolytic therapy with alteplase (tPA) versus standard of care for patients infected with COVID-19 resulting in severe respiratory failure. The design is a rapidly adaptive, pragmatic clinical trial, with 3 interim analyses and 1 final look at the data.
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: COVID-19; ARDS; SARS-CoV-2; Betacoronavirus