Cancer Drug May Render Certain COVID-19 Vaccines Less Effective

According to a recent study by researchers at Stanford Medicine, cancer patients who have been treated with rituximab, a widely used drug or similar drugs, respond poorly or not at all to subsequent COVID-19 mRNA vaccination.

In contrast, vaccination immediately before such treatments can generate a months-long, durable antibody response, found in the study published on Jan. 31, 2022, in Blood Cancer Discovery.

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

"This finding is likely to be practice-changing," said Ronald Levy, MD, professor of oncology, according to Krista Conger's reporting on Feb. 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 prior to treatment, most responded and were able to hold on to that response during their rituximab treatment."

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 virus that causes COVID-19.

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; last year, around 90,000 people were diagnosed with the disease in the U.S.

The drug, developed in collaboration with Levy's team in the early 1980s, binds to a molecule called CD-20 on the surface of B cells, a specialized type of immune cell that makes antibodies to combat pathogens.

Lymphomas are cancers that occur when B cells begin dividing uncontrollably, and rituximab seeks out and kills these cells in lymphoma patients.

Levy is the study's senior author, and Tanaya Shree, MD, Ph.D., was the lead author.

The researchers disclosed no industry conflicts of interest.