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Convalescent Plasma Saves Lives in Blood Cancer and COVID-19

blood plasma

June 21, 2021 -- A strong case for the routine use of convalescent plasma for people with blood cancer who are hospitalized with COVID-19 is made by the results from a study published in JAMA Oncology.

Patients with blood cancer are at a particularly high risk for severe complications from COVID because the cancer and its treatment make it harder for them to make antibodies to fight off infection. Convalescent plasma, obtained from people who have had COVID-19 and have recovered, provides such patients with antibodies.

The approach was useful during the Spanish flu pandemic in 1918, as well as during the more recent SARS and MERS coronavirus pandemics.

The team did the study after hearing doctors "around the country report remarkable clinical improvements," investigator Jeffrey Henderson, MD, PhD, an associate professor of medicine and molecular microbiology at Washington University in St. Louis, said in a statement.

"I have seen one of my own patients with blood cancer quickly improve after receiving convalescent plasma. Similar stories … suggested that a formal study" was in order, he said.

The investigators analyzed data from 70 institutions in the United States that were taking part in the COVID-19 and Cancer Consortium registry.

They pulled the records of 143 patients with blood cancers who received convalescent plasma while hospitalized for COVID-19, and they compared their death rate with that of 823 hospitalized patients who did not receive the plasma.

Among those who got plasma, 19 patients (13.3%) died within 30 days of being diagnosed with COVID-19, vs. 204 (24.8%) who didn’t get the plasma.

And among 388 patients who were admitted to the intensive care unit for respiratory and other complications, the death rate was 15.8% in the plasma group, vs. 46.9% for those who didn’t get the treatment.

Among 227 patients who were placed on ventilators, 30-day mortality was 17.8% with convalescent plasma, vs 53.3% without, a 68% reduction.

"As with any observational study, causality cannot be inferred from these findings, but rather these findings can be viewed as contributing to the accumulating evidence regarding survival benefit with convalescent plasma treatment in patients with COVID-19 illness," said investigators led by Michael Thompson, MD, PhD, a medical oncologist and hematologist at Advocate Aurora Health in Milwaukee, WI.

"Our findings, along with other similar cases not in this database, support using convalescent plasma to improve survival in these patients," he said in a news release.

Bridging the Gap

The findings fill "a major knowledge gap, as most studies on convalescent plasma" include few patients with cancer, said Gregory Calip, PharmD, PhD, a hematology/oncology epidemiologist and biostatistician at Flatiron Health in New York City. He commented with colleagues in an editorial that came with the study.

“Determining a causal treatment effect of convalescent plasma will ultimately require an appropriately designed clinical trial," the editorialists wrote.

Plasma Patients Were Sicker

Among the study limits, it's not known how many transfusions of convalescent plasma each person received, exactly when they got transfusions while they were in the hospital, and how the transfusions were timed with respect to the patients' cancer treatments. Another unknown is the antibody levels of the transfused plasma.

But those who got convalescent plasma were considerably sicker than control patients, with more sepsis and respiratory problems. They were also more likely to have chronic lymphocytic leukemia. In such patients, COVID-19 is linked to a particularly bad prognosis. These patients are more likely to receive corticosteroids and the antiviral remdesivir.

There was a worry there would be more thrombosis and acute kidney failure among the plasma group because of the transfusions, but that did not turn out to be the case. On the other hand, the slightly higher rate of heart failure in the plasma group, probably from volume overload, does bear watching, the investigators said.

The patients were treated from March 2020 to January 2021. It's likely most of them received plasma through the FDA's Expanded Access Program and subsequent emergency use authorization.

The mean age of the patients was 65 years, and slightly more than half were men. Multiple myeloma was the most common cancer diagnosis, making up about 20% of cases.

The study was funded by the National Institutes of Health and others. Several investigators have disclosed ties to industry, but none were related to this study. The editorialists were employed by Flatiron Health, which is owned by Roche.

Show Sources

Medscape.com: “Convalescent Plasma Saves Lives in Blood Cancer and COVID-19.”

Washington University School of Medicine: “Blood cancer patients with COVID-19 fare better with convalescent plasma.”

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