A Randomized Trial of Mesenchymal Stromal Cells for Moderate to Severe ARDS From COVID-19.

RATIONALE: There are limited therapeutic options for patients with COVID-19-related acute respiratory distress syndrome (ARDS) with inflammation-mediated lung injury. Mesenchymal stromal cells offer promise as immunomodulatory agents. OBJECTIVES: Evaluation of efficacy and safety of allogeneic mesenchymal cells in mechanically-ventilated patients with moderate or severe COVID-induced respiratory failure. METHODS: Patients were randomized to two infusions of 2 million cells/kg or sham infusions, in addition to standard of care. We hypothesized that cell therapy would be superior to sham-control for the primary endpoint of 30-day mortality. The key secondary endpoint was ventilator-free survival within 60 days, accounting for deaths and withdrawals in a ranked analysis. MEASUREMENTS AND MAIN RESULTS: At the third interim analysis, the Data and Safety Monitoring Board recommended that the trial halt enrollment as the pre-specified mortality reduction from 40% to 23% was unlikely to be achieved (n=222 out of planned 300). Thirty-day mortality was 37.5% (42/112) in cell recipients versus 42.7% (47/110) in control patients (RR 0.88;95% CI 0.64,1.21;p=0.43). There were no significant differences in days alive off ventilation within 60 days (median rank 117.3 [IQR:60.0,169.5] in cell patients and 102.0 [IQR:54.0,162.5] in controls; higher is better). Resolution or improvement of ARDS at 30-days was observed in 51/104 (49.0%) cell recipients and 46/106 (43.4%) of control patients (OR 1.36;95% CI 0.57, 3.21). There were no infusion-related toxicities and overall serious adverse events over 30 days were similar. CONCLUSIONS: Mesenchymal cells, while safe, did not improve 30-day survival or 60-day ventilator-free days in patients with moderate/severe COVID-related acute respiratory distress syndrome. Clinical trial registration available at www. CLINICALTRIALS: gov, ID:NCT04371393. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Mesenchymal stromal cell therapy for acute respiratory distress syndrome due to coronavirus disease 2019.

BACKGROUND AIMS: The acute respiratory distress syndrome (ARDS) resulting from coronavirus disease 2019 (COVID-19) is associated with a massive release of inflammatory cytokines and high mortality. Mesenchymal stromal cells (MSCs) have anti-inflammatory properties and have shown activity in treating acute lung injury. Here the authors report a case series of 11 patients with COVID-19-associated ARDS (CARDS) requiring mechanical ventilation who were treated with remestemcel-L, an allogeneic MSC product, under individual patient emergency investigational new drug applications. METHODS: Patients were eligible if they were mechanically ventilated for less than 72 h prior to the first infusion. Patients with pre-existing lung disease requiring supplemental oxygen or severe liver or kidney injury were excluded. Each patient received two infusions of remestemcel-L at a dose of 2 million cells/kg per infusion given 48-120 h apart. RESULTS: Remestemcel-L infusions were well tolerated in all 11 patients. At the end of the 28-day follow-up period, 10 (91%, 95% confidence interval [CI], 59-100%) patients were extubated, nine (82%, 95% CI, 48-97%) patients remained liberated from mechanical ventilation and were discharged from the intensive care unit and two (18%, 95 CI%, 2-52%) patients died. The median time to extubation was 10 days. Eight (73%, 95% CI, 34-100%) patients were discharged from the hospital. C-reactive protein levels significantly declined within 5 days of MSC infusion. CONCLUSIONS: The authors demonstrate in this case series that remestemcel-L infusions to treat moderate to severe CARDS were safe and well tolerated and resulted in improved clinical outcomes.

Remestemcel-L Therapy for COVID-19-Associated Multisystem Inflammatory Syndrome in Children.

Multisystem inflammatory syndrome in children (MIS-C) is a serious postinfectious immune dysregulation associated with coronavirus disease 2019 that may present with severe and life-threatening cardiovascular dysfunction, hemodynamic instability, shock, and multisystem organ failure. Optimal treatment is unknown. Current standard of care consists of nonspecific anti-inflammatory and antithrombotic therapies. Interventions that target MIS-C's distinctive clinical features and immunophenotype are indicated. Remestemcel-L, an investigational mesenchymal stromal cell therapy, is a promising candidate for treatment of MIS-C because of its beneficial anti-inflammatory, immunomodulatory, endothelial function and vascular stabilizing effects, which align well with the pathophysiology of MIS-C. Here, we present the first two patients with life-threatening MIS-C ever treated with remestemcel-L under an expanded access program. Both were previously healthy children without any indication of previous coronavirus disease 2019 infection or exposure. They presented with severe clinical illness including myocardial dysfunction, hemodynamic instability, hypotension, acute kidney injury, and shock. At the time of hospital admission, both had negative polymerase chain reaction (PCR) test results and positive serology results for severe acute respiratory syndrome coronavirus 2. Both children received standard of care MIS-C treatment. Although the patients showed some clinical improvement, left ventricular ejection fraction remained reduced and inflammatory biomarkers remained significantly elevated. When treated with two intravenous doses of remestemcel-L separated by 48 hours, rapid normalization of left ventricular ejection fraction, notable reductions in biomarkers of systemic and cardiac inflammation, and improved clinical status occurred. Neither child experienced adverse effects associated with remestemcel-L administration. This treatment appears promising as a novel immunomodulatory cellular therapy for children with clinically significant cardiovascular manifestations of MIS-C.