Booster May Up Antibodies in Patients With Cancer When Standard Dose Fails

Marcus A. Banks

November 23, 2021

People with cancer who do not develop antibodies against SARS-CoV-2 after a standard vaccination series may do so after receiving a COVID-19 booster, according to a new study.

The extra vaccine dose appears to be especially helpful for patients with blood cancers, many of whom do not have detectable antibodies after their initial full vaccination, researchers found.

"We had such a high conversion rate from no antibody response prior to the booster vaccine to an antibody response in the majority of those patients after [they received] the booster," lead author Lauren C. Shapiro, MD, a hematology/oncology fellow at Montefiore Medical Center/Albert Einstein College of Medicine, New York City, told Medscape Medical News. "That was way higher of a response than we were anticipating."

For their study, published online November 16 in Cancer Cell, Shapiro and colleagues analyzed data from two cohorts of patients with a cancer diagnosis: one that had received a booster and another that had only received the initial vaccine series.

In the booster cohort, 88 racially diverse patients received an additional vaccine dose 28 days or more after completing their standard vaccination series, most often with the Pfizer-BioNTech vaccine. The median age in this group was 69 years and two thirds had a hematologic malignancy.

Overall, patients with hematologic malignancies showed both a lower pre-booster antibody response as well as a smaller change in anti-spike IgG mean titers after the booster compared with patients with solid tumors (10,034 vs. 22,686 AU/mL, P =.003).

Fifty-six patients (64%) had detectable antibodies prior to the booster shot. Of the 32 patients (36%) without a measurable immune response, all except one had a hematologic malignancy. However, 18 of these patients (56%) developed antibodies after receiving the booster shot.

Fourteen patients (44%) — all of whom had some form of B-cell cancer — remained seronegative post-booster. Most of these patients had undergone immune-depleting treatments, such as anti-BTK or anti-CD20 therapy or both.

"The B-cells are the ones that produce antibodies, so when you have a cancer that has damaged the B-cells and you're targeting a therapy that kills that B-cell in an effort to control the cancer, you're kind of reducing your armamentarium to produce antibodies in general," said Astha Thakkar, MBBS, also a hematology/oncology fellow at Montefiore and the paper's co-lead author.

An analysis of 28 of the 56 patients who initially seroconverted found higher levels of antibodies after the booster than after the original full vaccination, "suggesting benefit to booster vaccination in the majority of patients with cancer," the authors write in their study.

In the other cohort of 99 patients who had completed vaccination 4 to 6 months earlier, the researchers looked at how anti-COVID-19 immunity waned over time. Overall, antibody titers had dropped considerably since vaccination, from a median of 5162 AU/mL right after vaccination to 724.6 AU/mL. All patients with solid tumors had detectable antibodies at follow-up, and only two with hematologic cancers did not.

Shapiro and Thakkar said the take-home message from their study is that boosters can be particularly valuable for people with cancer.

"The booster works very well, and maybe even gives you more protection than you had at first," Shapiro said.

The study did not have commercial funding. Two of the authors report ties to several drugmakers, but not to Pfizer or Moderna.

Cancer Cell. Published online November 16, 2021. Letter

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