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Convalescent plasma actions spark trial recruitment concerns


Investigators conducting randomized controlled clinical trials to gauge the utility of convalescent plasma in COVID-19 are uncertain how studies will be affected now that the US Food and Drug Administration has given an emergency use authorization (EUA) for the therapy.

The agency’s move took many investigators by surprise. The EUA was announced at the White House the day after President Donald J. Trump accused the FDA of delaying approval of therapeutics to hurt his re-election chances.

In a memo describing the decision, the FDA cited data from some controlled and uncontrolled studies and, primarily, data from an open-label expanded-access protocol overseen by the Mayo Clinic.

At the White House, FDA Commissioner Stephen Hahn, MD, said that plasma had been found to save the lives of 35 out of every 100 who were treated. That figure was later found to have been erroneous, and many experts pointed out that Hahn had conflated an absolute risk reduction with a relative reduction. After a firestorm of criticism, Hahn issued an apology.

“The criticism is entirely justified,” he tweeted. “What I should have said better is that the data show a relative risk reduction not an absolute risk reduction.”

About 15 randomized controlled trials – out of 54 total studies involving convalescent plasma – are underway in the United States, according to The FDA’s Aug. 23 emergency authorization gave clinicians wide leeway to employ convalescent plasma in patients hospitalized with COVID-19.

The agency noted, however, that “adequate and well-controlled randomized trials remain necessary for a definitive demonstration of COVID-19 convalescent plasma efficacy and to determine the optimal product attributes and appropriate patient populations for its use.”

But it’s not clear that people with COVID-19, especially those who are severely ill and hospitalized, will choose to enlist in a clinical trial – where they could receive a placebo – when they instead could get plasma.

“I’ve been asked repeatedly whether the EUA will affect our ability to recruit people into our hospitalized patient trial,” said Liise-anne Pirofski, MD, FIDSA, chief of the department of medicine, infectious diseases division at Albert Einstein College of Medicine and Montefiore Medical Center in the Bronx, New York. “I do not know,” she said, on a call with reporters organized by the Infectious Diseases Society of America.

“But,” she said, “I do know that the trial will continue and that we will discuss the evidence that we have with our patients and give them all that we can to help them weigh the evidence and make up their minds.”

Pirofski said the study being conducted at Montefiore and four other sites has since late April enrolled 190 patients out of a hoped-for 300.

When the study – which compares convalescent plasma to saline in hospitalized patients – was first designed, “there was not any funding for our trial and honestly not a whole lot of interest,” Pirofski told reporters. Individual donors helped support the initial rollout in late April and the trial quickly enrolled 150 patients as the pandemic peaked in the New York City area.

The National Institutes of Health has since given funding, which allowed the study to expand to New York University, Yale University, the University of Miami, and the University of Texas at Houston.


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