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Cancer Drug Likely Renders COVID-19 mRNA Vaccine Ineffective

February 4, 2022 • 10:45 am CST
(Vax Before Cancer)

People who have been treated with the cancer drug rituximab or similar drugs respond poorly or not at all to subsequent COVID-19 mRNA vaccines, according to a study published by researchers at Stanford Medicine on January 31, 2022.

Rituximab, marketed under the brand name Rituxan, is widely used alone or in combination with other treatments in people with lymphomas, a type of blood cancer.

It targets a molecule called CD-20 found on the surface of immune cells called B cells.

In 2021, around 90,000 people were diagnosed with the disease in the United States.

However, the researchers did not directly assess whether patients treated with rituximab or with other drugs targeting CD-20 before being vaccinated subsequently had higher infection rates with the SARS-CoV-2 coronavirus that causes COVID-19.

But the findings strongly suggest that people who are newly diagnosed with lymphoma should be offered an mRNA vaccine before beginning rituximab or similar drugs.

“This finding is likely to be practice-changing,” said Ronald Levy, MD, professor of oncology, in a press statement issued on February 2, 2022.

“We found that antibody responses to the COVID-19 vaccine were blunted in people who received rituximab up to a year before vaccination. But if they were vaccinated before treatment, most responded and were able to hold on to that response during their rituximab treatment.”

Note: On December 2, 2021, the U.S. FDA Approved rituximab (Rituxan, Genentech, Inc.) in combination with chemotherapy for pediatric patients (≥6 months to <18 years) with previously untreated, advanced stage, CD20-positive diffuse large B-cell lymphoma, Burkitt lymphoma, Burkitt-like lymphoma, or mature B-cell acute leukemia.