Third COVID-19 Vaccine Dose in Blood Cancers May Boost Antibody Production

More than half of patients with B-cell blood cancers who did not have detectable antibodies after the first two doses of a COVID-19 vaccine produced antibodies after a third dose, although some patients may not have a full antibody response even with the additional dose.

Researchers of the study conducted by The Leukemia & Lymphoma Society also determined that immune suppressing treatments may diminish a patient’s vaccine immune response.

“Our ongoing project in this case was to follow patients who have had that additional dose to see if they responded,” Dr. Larry Saltzman, the executive research director at the Leukemia & Lymphoma Society, told CURE®. “It's very important because we want people to be safe and guarded from COVID-19. The initial studies with hospitalized patients showed that blood cancer patients were especially susceptible, with over 50% of blood cancer patients admitted to the ICU dying of COVID-19. That's way above the average. We're very sensitized to what's happening and how we can protect our constituency.”

Recommendation for a Third Vaccine Dose

This study provides more insight into the potential benefits of a third dose of a COVID-19 vaccine. In August, the Food and Drug Administration authorized a third dose of either mRNA COVID-19 vaccine — Pfizer or Moderna — for patients who are immunocompromised. In addition, the Centers for Disease Control and Prevention recommended this additional dose for those who are immunocompromised, which LLS says includes most blood cancer patients.

In this study, researchers assessed the effects of a third COVID-19 vaccine dose in 49 patients (average age, 66 years; 57% men) with B-cell blood cancers including chronic lymphocytic leukemia (CLL), Waldenstrom’s macroglobulinemia, multiple myeloma and other subtypes. Of these patients, 35% did not respond to the first two doses of the COVID-19 vaccine and had no change in antibody levels after the third dose, although 65% of patients had increased antibody levels after the third vaccine dose.

“Even though somebody may say, ‘Well, the first two (COVID-19 vaccine doses) don’t do anything,’ we’re finding a majority of people who have the third dose do have a response,” Saltzman explained. “It’s really only tempered by the treatments that they’re on and the vaccines are just as safe in blood cancer patients, so I don’t see any reason why any patient shouldn’t get the vaccine.”

Saltzman added that potentially the only reason that a patient should not get vaccinated is if they are undergoing treatment with a bone marrow transplant. These patients should not be vaccinated for anything within the first three months of their transplants.

B cells create antibodies that float around a patient’s body and target foreign substances like COVID-19, Saltzman explained. Once B cells cover COVID-19, other parts of our body’s defense system like T cells and macrophages work together to get rid of the virus. This functions differently in patients with B cell blood cancers.

“In patients with these illnesses, their B cells are not functioning,” Saltzman said. “If B cells don’t function and we provide a vaccine to patients, it’s likely that they’re not going to create antibodies because their B cells are not working to create that kind of response.”

A Treatment’s Impact on Antibody Levels

A patient’s ability to create antibodies as a response to the COVID-19 vaccine may also be impacted by the type of treatment they are receiving. This can include Rituxan (rituximab) and Gazyva (obinutuzumab), which can stay in a patient’s system for six to 12 months, or even longer. This may also apply to BTK inhibitors like Imbruvica (ibrutinib), though to a lesser degree. Despite this, Saltzman mentioned that patients should not hold back their treatment to receive a COVID-19 vaccine.

“We’re worried — and I am a CLL patient myself, and I would be worried — that by withholding treatment, one could trigger a relapse if somebody is in remission or their blood cancer is being controlled with these treatments,” Saltzman said. “As in any kind of cancer, it’s always harder to treat a relapse or a second occurrence than it is to treat the initial occurrence. Everybody needs to talk to their physician or their oncology team about what to do.”

Saltzman noted his personal opinion as a patient with CLL.

“My view of this pandemic and my life is that I would rather be in remission from blood cancer and then take extra precautions to shield myself from COVID,” he said. “I still may get a breakthrough infection because the Delta (variant) is very contagious. We have to prioritize which we’d rather be, and I would rather be in remission. Although my lifestyle is living in a bubble and more restricted, I would rather be like that.”

Even in patients with B cell blood cancers who respond to the COVID-19 vaccine, it’s important for them to take precautions to protect themselves against breakthrough infections.

“In the end, we find that probably anybody with a blood cancer, where their white blood cells are not as normal as they could be, have to be careful about (COVID-19),” Saltzman said. “And so (the Leukemia & Lymphoma Society) has taken up … a mantra that says, ‘Get vaccinated, but act unvaccinated.’”

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