For people very sick with the new coronavirus, access to a mechanical ventilator can mean life or death. Trouble is, they're in short supply in the United States and around the world.
Now, research suggests that a widely used clot-busting stroke drug might help coronavirus patients who can't access a ventilator or who fail to improve even when they do gain access.
The research focuses on a drug called tissue plasminogen activator (tPA), which is normally used to quickly dissolve blood clots that cause strokes or heart attacks.
New data from China and Italy suggest that people with Covid-19, the disease caused by the coronavirus, have a significant blood-clotting disorder.
Patients in respiratory failure develop blood clots in the lungs and tiny blockages in the lung's blood vessels. These tiny clots keep blood from reaching air spaces in the lungs, and that's where blood normally receives oxygen from the lungs.
"This is a way to repurpose a drug for which there is already widespread clinical utility," said senior researcher Dr Michael Yaffe, a professor of biology and biological engineering at Massachusetts of Institute of Technology.
Dr Hunter Moore, a transplant fellow at the University of Colorado Denver, is a study co-author.
"Everyone is looking for ways to mitigate the threat of this disease, and there's a lot of investment and interest in new drugs," Moore said. "But if this disease gets out of control, those drugs won't have had safety evaluations. TPA has."
While well-studied in stroke and heart attack, the use of tPA for acute respiratory distress syndrome has mostly been investigated in animals. A small human trial was conducted in 2001 on people with severe respiratory distress who weren't expected to survive.
Potential therapeutic value
Moore said tPA reduced the death rate in those patients from 100% to 70%.
The researchers noted that further studies haven't been done because people typically improve well with the support of ventilators. But as Covid-19 overwhelms the health care system, there may not be enough ventilators for patients who need them.
"TPA may potentially hold therapeutic value in treating severely ill Covid-19 patients with acute respiratory distress syndrome that is unresponsive to typical ventilation strategies," said Dr Robert Glatter, an emergency physician at Lenox Hill Hospital in New York City.
He said the science supporting its use is sound.
"Tiny clots block small blood vessels in the lungs, preventing adequate oxygenation and ventilation," said Glatter, who wasn't part of the study. "The drug also prevents clots from blocking blood vessels in the kidney and heart, leading to kidney and heart failure. TPA dissolves the clots, opening up small blood vessels, improving the ability of the lungs and other critical organs to function normally."
A 'compassionate trial'
While bleeding is a potential risk of tPA, Glatter noted that this didn't happen in the one study that was done.
Yaffe said researchers are planning a "compassionate use" trial of the drug on Covid-19 patients, possibly beginning within a week, to see if tPA helps these patients. They will be assessing both intravenous tPA and inhaled tPA.
A compassionate use trial allows patients with a serious or life-threatening illness to receive an investigational therapy.
Patients selected for the trial will either be on ventilators or appear to need ventilation. They will be high-risk patients who have potentially deadly acute respiratory distress syndrome.
The researchers hope to test tPA in 12 people, but will evaluate its effectiveness and safety after four patients.
The dose of tPA they'll use is lower than that typically prescribed for stroke or heart attack patients. It will also be delivered over a longer time period.
Yaffe said tPA's manufacturer, Genentech, is providing the study medication for free. If the trial is successful, the drug maker has told researchers it is prepared to ramp up production.
Given the increasing rate of Covid-19 infections, the researchers hope the trial might begin as soon as next week.
"Extraordinary times call for extraordinary measures. If an observational trial of this treatment in the first series of patients is effective and safe, the approach could be readily broadened. This would have multiple patient-related and public health benefits," the researchers said in their study.
*Published online in the Journal of Trauma and Acute Care Surgery.