Convalescent Plasma Actions Spark Trial Recruitment Concerns

Alicia Ault

August 26, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

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 (FDA) 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 August 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.

Dr Liise-anne Pirofski during today's telebriefing.

"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.

Hopeful, But a Long Way to Go

Dr Shmuel Shoham during today's telebriefing.

Shmuel Shoham, MD, FIDSA, associate director of the transplant and oncology infectious diseases center at Johns Hopkins University School of Medicine in Baltimore, Maryland, said that he's hopeful that people will continue to enroll in his trial, which is seeking to determine if plasma can prevent COVID-19 in those who've been recently exposed.

"Volunteers joining the study is the only way that we're going to get to know whether this stuff works for prevention and treatment," Shoham said on the call. He urged physicians and other healthcare workers to talk with patients about considering trial participation.

Shoham's study is being conducted at 30 US sites and one at the Navajo Nation. It has enrolled 25 out of a hoped-for 500 participants. "We have a long way to go," said Shoham.

Another Hopkins study to determine whether plasma is helpful in shortening illness in nonhospitalized patients, which is being conducted at the same 31 sites, has enrolled 50 out of 600.

Shoham said recruiting patients with COVID for any study had proven to be difficult. "The vast majority of people that have coronavirus do not come to centers that do clinical trials or interventional trials," he said, adding that in addition, most of those "who have coronavirus don't want to be in a trial. They just want to have coronavirus and get it over with."

But it's important to understand how to conduct trials in a pandemic — in part to get answers quickly, he said. Researchers have been looking at convalescent plasma for months, said Shoham. "Why don't we have the randomized clinical trial data that we want?"

Pirofski noted that trials have also been hobbled in part by "the shifting areas of the pandemic." Fewer cases make for fewer potential plasma donors.

Both Shoham and Pirofski also said that more needed to be done to encourage plasma donors to participate.

The US Department of Health & Human Services clarified in August that hospitals, physicians, health plans, and other healthcare workers could contact individuals who had recovered from COVID-19 without violating the HIPAA privacy rule.

Pirofski said she believes that trial investigators know it is legal to reach out to patients. But, she said, "it probably could be better known."

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