Study limitations and lessons
Although the findings of this study are limited by the small number of patients, the fact that treatment and disease were patient reported, and a lack of data on “antibody responses, particularly to the delta variant, B-cell memory, or T-cell responses,” they nevertheless provide encouraging news, Dr. Nichols told this news organization.
“Many blood cancer patients are getting boosters and a good number are able to make antibody with an additional dose. This is giving us much needed information about boosters,” she said. “Through the LLS National Patient Registry, we anticipate having data on hundreds of more patients over the course of the next few months.”
The information is needed because data suggest that up to 25% of patients with hematologic malignancies fail to make anti-S antibodies after full COVID-19 vaccination and that seronegative patients may be especially vulnerable to breakthrough infections, she and her colleagues noted.
Patients with B-cell malignancies are at the highest risk, and this is particularly concerning as some patients with blood cancer who contracted COVID-19 in the prevaccine period of the pandemic had “prolonged, severe infections; generated variant strains; and demonstrated significantly higher mortality rates compared to the general population,” they said.
However, a recently published placebo-controlled trial that demonstrated a booster vaccination–mediated increase in anti-S antibodies and neutralizing antibodies in immunosuppressed patients, and the current review, which focused on patients who obtained booster vaccinations prior to Aug. 12, 2021 (when the Food and Drug Administration granted emergency use authorization for booster doses in immunocompromised people), offer findings that suggest these patients may benefit from receiving COVID-19 boosters.
“We conclude that some patients with hematologic malignancies who are seronegative after a full course of vaccination may benefit from a booster,” the authors wrote. They added a warning: “Regulators, patients, and health care providers should be aware that a sizable subset of patients with blood cancer may remain at risk of breakthrough COVID-19 infections after full vaccination followed by booster vaccination.”
Dr. Nichols stressed that the findings “do not in any way suggest that blood cancer patients should stop therapy to get an antibody response to the vaccinations.”
“LLS is encouraging blood cancer patients to get vaccinated and to continue taking preventive measures such as wearing masks, social distancing, hand washing, and avoiding crowds and poorly ventilated indoor spaces,” she said.
Sergio Giralt, MD, professor and deputy head of the division of hematologic malignancies at Memorial Sloan Kettering Cancer Center, New York, further emphasized the importance of preventive measures.
“I think the extra booster will go a long way to protect our patients at this time but should not be used as a replacement for masking indoors and continued social distancing in this vulnerable patient population,” he said.
This study was supported by the LLS.