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DJ FDA Limits Use of Convalescent Plasma as Covid-19 Treatment

· 02/05/2021 10:00
By Amy Dockser Marcus

The Food and Drug Administration is scaling back its authorization of the use of convalescent blood-plasma for Covid-19 patients in an effort to guide physicians who have faced a confusing thicket of data about the therapy's effectiveness.

The agency said late Thursday that the authorization, a subject of controversy since it was first issued last August, would be revised to limit the use of plasma to hospitalized patients early in the course of the disease and hospitalized patients with a medical condition that impairs their ability to make antibodies. Patients will be allowed to receive only plasma containing high concentrations of antibodies.

"The update is meant so convalescent plasma can best be used on those who will benefit," said Peter Marks, director of the FDA's Center for Biologics Evaluation and Research. "It is being used somewhat more indiscriminately."

Dr. Claudia Cohn, chief medical officer of AABB, an organization representing the transfusion-medicine community, said the group plans to issue interim recommendations on convalescent plasma later this month. "There are so many studies coming out with different conclusions," she said. "It is not clean, it is not black and white."

Dr. Marks said the FDA reached its decision after evaluating results from several recent studies. Some showed benefits from convalescent plasma, the antibody-containing fluid derived from the blood of people who have recovered from Covid-19. Others showed no benefit.

Two clinical trials of convalescent plasma for hospitalized patients shut down last month after investigators said there appeared to be no benefit. Three trials involving hospitalized patients recently reported some benefit for the plasma, but only when given to patients soon after admission. Still another trial showed that elderly outpatients given plasma shortly after showing symptoms were less likely to develop serious disease.

Arturo Casadevall, chair of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, called the FDA decision "a step forward." He said, "Physicians in the U.S. for the first time are going to have guidance on when to use it and how to use" convalescent plasma.

Dr. Casadevall is a co-founder of the Covid-19 Convalescent Plasma Project, which helped organize a nationwide expanded-access study of convalescent plasma that began last April.

Despite the contradictory findings, convalescent plasma remains in demand -- in part because there are few effective treatments for Covid-19 and many people remain unvaccinated. Since the FDA issued the emergency authorization last August, the blood industry has distributed on average about 20,600 units of convalescent plasma a week to hospitals around the country, according to the American Red Cross.

The FDA's earlier decision to authorize convalescent plasma for hospitalized Covid-19 patients was based in large part on results from an agency-sponsored expanded-access program, through which more than 72,000 patients received plasma. For a study published last month in the New England Journal of Medicine, researchers analyzed data from 3,000 of those patients and reported an apparent survival benefit among hospitalized patients not on mechanical ventilation who received plasma containing high concentrations of antibodies.

But many scientists expressed skepticism about that finding, saying expanded-access studies lack the scientific rigor of traditional trials because they have no control group to compare any apparent effect.

The FDA's Dr. Marks said the authorization of convalescent plasma "could have been handled much better. It had to do with the sense of urgency everyone is feeling. I can't blame anyone for feeling a sense of urgency."

Dr. Marks also said the data could be confusing. Each unit of convalescent plasma is unique, reflecting the immune response of the recovered patient who donated it. It took time to figure out the best way to measure the antibodies in a unit, he added.

The U.S. isn't the only government trying to establish reliable guidelines on the use of convalescent plasma. In Argentina, a study in elderly outpatients published last month in the New England Journal of Medicine contributed to current recommendations there to treat elderly Covid-19 patients early in the course of their illness. "Plasma supplies are not endless, and invariably public health officials face difficult decisions," said study co-author Dr. Fernando Polack of Fundación Infant in Buenos Aires. "In any of these decisions, guidelines based on data are necessary and are the best way for clinicians to feel comfortable when facing individual cases."

Louis M. Katz, chief medical officer of Mississippi Valley Regional Blood Center in Davenport, Iowa, which provides blood products for over 120 hospitals, said the evidence supporting the use of convalescent plasma in hospitalized patients is weak. "I think the data is there that it works early," he said. "As you move into sicker and sicker people, the evidence gets thinner and thinner."

In an editorial that accompanied the New England Journal of Medicine paper on the U.S. expanded-access study, Dr. Katz said convalescent plasma should be used only in patients early in the course of the disease. The problem with that suggestion, he later added, is the FDA emergency-use authorization still covers only hospitalized patients, who tend to show up at the hospital when they have been sick for a longer time.

Treating Covid-19 patients who are just starting to show symptoms poses its own challenges. "Logistically, it is very difficult to treat patients earlier," Dr. Katz said. "It's hard to transfuse lots of plasma in outpatients."

Dr. Marks said a large National Institutes of Health study is now under way to test convalescent plasma in people with Covid-19 who are sick enough to come to the emergency room but aren't admitted to the hospital, as are other randomized controlled trials of plasma in outpatients. "Until we have those data, we are going to keep the authorization to hospitalized patients," he said. "We will refine it again if appropriate. This is a scarce resource."

Write to Amy Dockser Marcus at amy.marcus@wsj.com

(END) Dow Jones Newswires

February 05, 2021 10:00 ET (15:00 GMT)

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