Study: Most Blood Cancer Patients Could Benefit From Additional Dose of COVID-19 Vaccine


Among 38 patients with B-cell derived malignancies who were seronegative after 2 COVID-19 vaccine doses, 55% had detectable antibodies after the third dose whereas 45% remained seronegative.

More than half of patients with B-cell blood cancers produced an antibody response to a third dose of the COVID-19 vaccine, according to research from the Leukemia and Lymphoma Society (LLS). In addition to these findings, the study showed that patients who had detectable antibodies after the 2 primary vaccine doses had increased levels following a third dose.

According to a press release, LLS recommends that patients with blood cancer who received 2 doses of either the Moderna or Pfizer-BioNTech mRNA vaccine receive an additional dose according to CDC guidance. Further guidance will be coming soon for individuals who received Johnson and Johnson’s COVID-19 vaccine.

“The additional COVID-19 vaccine dose appears to be improving immune response in many people with blood cancer—one of many conditions that can suppress a person’s immune system,” said Gwen Nichols, MD, chief medical officer at LLS, in the press release. “However, while vaccination offers protection to the majority of blood cancer patients, some will not mount a full antibody response even with this additional dose.”

In the study, researchers found that treatment with the antibody rituximab in the 6 to 12 months prior to vaccination was associated with a failure to produce detectable COVID-19 antibodies, even after receiving a third dose of the vaccine. Rituximab uniformly blunted immune response in this study, according to the press release, and the authors noted that it is also used for patients with rheumatic diseases. Studies among patients with rheumatoid arthritis and lupus who were receiving rituximab have also found low seroconversion rates following the first 2 doses of mRNA COVID-19 vaccines.

“As this LLS study and other rheumatology studies have shown, patients receiving rituximab may be at particularly high risk to not mount an antibody response after vaccination against COVID and following other vaccines,” said Jeffrey Curtis, MD, MS, MPH, chair of the American College of Rheumatology (ACR) COVID Vaccine Guidance Task Force, in the press release. “It is for this reason that the ACR Task Force suggested that optimizing the timing of vaccination for rheumatology patients on rituximab may yield an improved response to primary vaccination and supplemental (booster) dosing.”

Furthermore, some patients also failed to make detectable COVID-19 antibodies because they were receiving treatment with Bruton’s tyrosine kinase (BTK) inhibitors, although the press release noted that individual results in these patients were variable.

An earlier study with more than 1400 patients with blood cancer found that approximately 1 in 4 failed to produce detectable antibodies after 2 doses of either the Moderna or Pfizer mRNA COVID-19 vaccines. However, these rates varied by cancer type and patients with non-Hodgkin lymphoma or chronic lymphocytic leukemia were least likely to have detectable antibodies.

In the new study, among 38 patients with B-cell derived malignancies who were seronegative after 2 vaccine doses, 55% had detectable antibodies after the third dose whereas 45% remained seronegative. The 11 patients who had measurable antibodies after the primary doses had increased antibody levels following the third dose. Even in this difficult-to-immunize population, the authors said the majority have detectable antibodies.

“Antibody levels in our study ranged from 2.2 to over 2500,” said Lee Greenberger, PhD, chief scientific officer at LLS, in the press release. “Antibodies tell us that a patient has responded to vaccination—and that is a positive finding, but vaccine experts are still working to determine exactly what antibody level is needed to protect against COVID-19 infection or its worst outcomes.”

Importantly, current cancer treatment guidelines do not advise delaying treatments or COVID-19 vaccination in patients with blood cancer. According to the press release, patients with blood cancer should consult with their health care team about getting vaccinated and should continue taking other safety measures, such as wearing masks and social distancing.


New Study Shows Most Blood Cancer Patients Benefit from an Additional COVID-19 Vaccine Dose. News release. Leukemia and Lymphoma Society; September 13, 2021. Accessed September 21, 2021.

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